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  • 101.
    Karpinnen, Helene
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Förekomst av heteroforier och heterotropier bland hjälpsökande i Nicaragua2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Att ta reda på förekomst av heteroforier och heterotropier hos hjälpsökande människor på en Vision for All-resa i Nicaragua.

    Metod: Efter en enkel subjektiv refraktion genomfördes covertest på både avstånd (fem meter) och nära (40 centimeter) med eventuell korrektion vid behov. 684 personer undersöktes i åldrarna 5-95 år. Eso- exo- och vertikalfori samt eso- exo- och vertikaltropi noterades liksom ortofori. Ingen mätning av deviationerna genomfördes.

    Resultat: 91 personer (13,3 %) hade en deviation vid avståndsfixation som framkom av covertestet. Exofori fanns hos 9,5 % och esofori hos 1,9 %. Av alla undersökta hade 1,9 % någon form av tropi på avstånd. 274 personer (40,1 %) hade en deviation vid fixation på 40 cm. Exofori fanns hos 36,5 % och esofori hos 1,8 %. 1,6 % av alla undersökta hade en tropi vid 40 cm.

    Slutsats: Studien visar att det vanligast förekommande tillståndet hos de undersökta är ortofori. Exofori är den vanligast förekommande deviationen på avstånd och är ännu vanligare på nära.

  • 102.
    Kristiansson, Håkan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The Effect of Optical Defocus on the Peripheral Resolution Acuity in Old Healthy Emmetropes2011Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 103.
    Kristiansson, Håkan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Lewis, Peter
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosén, Robert
    Biomedical and X-Ray Physics.
    Unsbo, Peter
    Biomedical and X-Ray Physics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Effect of Optical Defocus on Peripheral Resolution Acuity in Old Healthy Emmetropes2011Conference paper (Refereed)
    Abstract [en]

    Background:

    A recent study by Rosén et al found peripheral low contrast resolution acuity, but not high contrast acuity, to be affected by defocus in young healthy eyes. Since aging causes considerable degradation in peripheral optics even in healthy subjects we wanted to see if, older subjects were also sensitive to defocus in low contrast acuity.

     

    Purpose:

    The aim of this study was to evaluate the effect of optical defocus on high and low contrast resolution acuity in the peripheral visual field of healthy older emmetropes.

     

    Subjects:

    High- and low-contrast resolution acuity was evaluated under spherical defocus in the 20° nasal visual field of four healthy older emmetropic subjects. The off-axis refractive error at the 20° nasal visual field was measured by a COAS-HD VR aberrometer and was corrected accordingly for each subject.

     

    Methods:

    Resolution thresholds for visual acuity (VA) were obtained using stimuli consisting of high- (100%) and low- (10%) contrast gratings that were presented on a CRT monitor situated 1.0 meter from the subject. Stimuli, 3° in diameter were presented for 300 ms using a 2AFC paradigm. Two repeated measurements, for both high and low contrast, were obtained for each point of defocus in 1.0 D steps up to ±4 D at 45mm vertex distance. The results are corrected to effective defocus at the corneal plane.

     

    Results:

    Defocus had no visible effect on high contrast VA, although there was a slight decrease in VA with higher amounts of positive defocus. However, defocus was found to have a significant effect on low contrast VA. Moreover, low contrast resolution was more sensitive to positive defocus than the negative defocus.

     

    Conclusions:

    Defocus has an impact on low contrast resolution whereas no such effect was found for high contrast resolution. These results are similar to those obtained by Rosén et al1 in young eyes. These results suggest that low contrast optotypes could possibly be used for determining subjective refraction in low vision subjects.

  • 104.
    Larson, Malin
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Visusskillnad med Air Optix® och Air Optix® for Astigmatism vid låg astigmatism2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie var att kontrollera om och i så fall hur mycketvisus förbättras med toriska linser jämfört med sfäriska linser vid astigmatism -0,50 D - -1,00 D.

    I studien ingick tolv försökspersoner, fördelat på nio kvinnor och tre män, medcylinder mellan -0,50 D och -1,00 D på ett eller båda ögonen korrigerades först medAir Optix® (sfärisk) beräknad på sfärisk ekvivalent och sedan med Air Optix forAstigmatism®(torisk) med styrkor baserade på refraktionen. Högkontrastvisus ochlågkontrastvisus mättes både monokulärt och binokulärt.

    I studien framkom att i både monokulärt och binokulärt finns en statistisktsignifikant förbättring med den toriska linsen jämfört med den sfäriska. Ävenlågkontrastvisus visar en förbättring både monokulärt och binokulärt med den toriskalinsen, denna skillnad är inte statistiskt signifikant. Även vid 0,50 D cylinder finnsäven här en förbättring med den toriska linsen men denna är inte heller statistisktsignifikant, varken för hög eller lågkontrastvisus. För 1,00 D cylinder är förbättringensignifikant vid högkontrast men inte vid lågkontrastS. I likhet med tidigare studier har denna studie visat att även lågastigmatism drar fördel av korrigeras med toriska linser.

  • 105.
    Lefdal, Astrid
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Effect of the accommodative stimulus and testing distance on the gradient AC/A2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 106.
    Lewis, Peter
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Rosen, Robert
    Royal Institute of Technology KTH.
    Lundström, Linda
    Royal Institute of Technology KTH.
    Unsbo, Peter
    Royal Institute of Technology KTH.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Objectively Determined Refraction Improves Peripheral Vision2014In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 91, no 7, p. 740-746Article in journal (Refereed)
    Abstract [en]

    Purpose. The purpose of this study was twofold: to verify a fast, clinically applicable method for determining off-axis refraction and to assess the impact of objectively obtained off-axis refractive correction on peripheral low-contrast visual acuity. Methods. We measured peripheral low-contrast resolution acuity with Gabor patches both with and without off-axis correction at 20 degrees in the nasal visual field of 10 emmetropic subjects; the correction was obtained using a commercial open-field Hartmann-Shack wavefront sensor, the COAS-HD VR aberrometer. Off-axis refractive errors were calculated for a 5-mm circular pupil inscribed within the elliptical wavefront by COAS using the instruments' inbuilt "Seidel sphere" method. Results. Most of the subjects had simple myopic astigmatism, at 20 degrees in the nasal visual field ranging from -1.00 to -2.00 DC, with axis orientations generally near 90 degrees. The mean uncorrected and corrected low-contrast resolution acuities for all subjects were 0.92 and 0.86 logMAR, respectively (an improvement of 0.06 logMAR). For subjects with a scalar power refractive error of 1.00 diopters or more, the average improvement was 0.1 logMAR. The observed changes in low-contrast resolution acuity were strongly correlated with off-axis astigmatism (Pearson r = 0.95; p < 0.0001), the J(180) cross-cylinder component (Pearson r = 0.82; p = 0.0034), and power scalar (Pearson r = -0.75; p = 0.0126). Conclusions. The results suggest that there are definite benefits in correcting even moderate amounts of off-axis refractive errors; in this study, as little as -1.50 DC of off-axis astigmatism gave improvements of up to a line in visual acuity. It may be even more pertinent for people who rely on optimal peripheral visual function, specifically those with central visual field loss; the use of open-field aberrometers could be clinically useful in rapidly determining off-axis refractive errors specifically for this patient group who are generally more challenging to refract.

  • 107.
    Lewis, Peter
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosén, Robert
    Biomedical & X-Ray Physics.
    Unsbo, Peter
    Biomedical & X-Ray Physics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Clinical Impact of Objectively Determined Peripheral Refractive Error Correction on Low-Contrast Resolution AcuityManuscript (preprint) (Other academic)
  • 108.
    Lewis, Peter
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Holm, Victoria
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Dynamic Stimulus Presentation Facilitates Peripheral Resolution Acuity2013In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 54, article id e-abstract 574Article in journal (Other academic)
    Abstract [en]

    Purpose: Peripheral high-contrast resolution is sampling limited; the center to center spacing between ganglion cells ultimately limiting visual performance (Thibos et al., 1987). Although retinal image motion in the fovea has a detrimental effect on visual acuity, previous studies have suggested that retinal image motion may be advantageous in the peripheral visual field (Bex et al., 2003; Brown, 1972; Macedo et al., 2010). The aim of this study was to evaluate the effect of drift motion on peripheral resolution acuity.

    Methods: Peripheral high-contrast resolution acuity in a group of 26 subjects (age 23.5 ± 3.2 years) was initially determined using a 2-alternative forced-choice Bayesian algorithm; the threshold value defined as the spatial frequency resulting in a 75% correct response rate. The stimuli used to measure static visual acuity were stationary Gabor-patches with a visible diameter of 2° and were presented at 20° in the nasal visual field. We determined the percentage correct response rate for varying velocities using drifting Gabor patches of the same spatial frequency as determined during measurement of static visual acuity. The sine-wave gratings drifted within the Gaussian envelope at one of 10 angular velocities, varying from 0.2 to 2.0 degrees/second in 0.2 degrees/second steps.

    Results: Results showed an overall improvement in the subjects’ performance for all velocities. There was a significant difference in the percentage of correct responses between static stimulus presentation and for velocities of between 0.4 to 1.2 degrees/second (p < 0.05, One-way repeated measures ANOVA with Bonferroni post hoc tests). The average “correct response” for static stimulus presentation was 76 ± 2 %, improving to at least 85 % for velocities between 0.4 to 1.2 degrees/second. At velocities greater than 1.2 degrees/second performance was still better than for static stimulus presentation, but showed a gradual decline with increasing speed.

    Conclusions: In line with previous studies stimulus motion has a positive effect on peripheral high-contrast resolution acuity. Presenting moving stimuli may benefit patients who rely on peripheral visual function, such as those with central visual field loss subsequent to AMD.

  • 109.
    Lewis, Peter
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosén, Robert
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Carius, Staffan
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Unsbo, Peter
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Dynamic Visual Acuity in the Peripheral Visual Field Using Gabor Patches2010Conference paper (Refereed)
    Abstract [en]

    Purpose:To evaluate dynamic visual acuity (DVA) in the peripheral visual field. This ability is important within the areas of sports, traffic safety, as well as for people with low vision; specifically those with central visual field loss. In this study we investigated both static- and dynamic visual acuity in the periphery of normally sighted observers using Gabor patches.

    Methods:DVA and static visual acuity (SVA) was measured on the right eye of normally sighted emmetropes. Stimuli consisted of high-contrast Gabor patches; sine wave gratings multiplied by a Gaussian hull with a diameter of 2º, with the sine gratings drifting at 1, 2, and 4 degrees per second. Stimuli were presented, using MATLAB and Psychophysics Toolbox, on one of seven CRT monitors at the following retinal eccentricities: 10, 20 and 30 degrees, nasally and temporally as well as in the fovea. Subjects were informed to maintain fixation on a central fixation object during measurements at eccentric locations. An Adaptive Bayesian algorithm was employed to determine resolution thresholds at each eccentricity.

    Results:The results show a trend towards both better static- and dynamic visual acuities for the temporal visual field at retinal eccentricities 20° and 30° compared to nasally. There appears to be a more rapid decrease in both static- and dynamic visual acuity with increasing eccentricity for the nasal visual field. In addition, we did not find any difference in DVA and SVA in the peripheral visual field for the velocities used in this study.

    Conclusions:Results of these first preliminary measurements suggest that dynamic visual acuity measured with drifting Gabor patches is greater in the temporal visual field for eccentricities 20 degrees or larger. To confirm these results more measurements need to be performed on a lager sample of subjects.

  • 110.
    Lewis, Peter
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosén, Robert
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Unsbo, Peter
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Naso-temporal Asymmetry of Peripheral Static and Dynamic Visual Acuity2011Conference paper (Refereed)
    Abstract [en]

    Summary

    Static and dynamic visual acuity was evaluated in the peripheral visual field on normally sighted emmetropes. The results show a significant asymmetry for both static and dynamic visual acuity between the nasal and temporal visual fields.

     

    Introduction

    It is well known that visual performance thresholds decrease rapidly with increasing retinal eccentricity1. This reduction in performance can be attributed to both optical factors and reduced neural sampling2-3; the latter being the predominant limiting factor in the peripheral retina3.  Previous studies have shown that slowly moving stimuli are more easily resolved than stationary stimuli in the peripheral retina4. There is little evidence published regarding resolution thresholds for moving stimuli in more than a few limited directions in the visual field.     

    In this study, static visual acuity (SVA) and dynamic visual acuity (DVA) thresholds were measured at 10° intervals both nasally and temporally on healthy, young emmetropes. DVA was measured at angular velocities of 1 °/s and 2 °/s using drifting Gabor patches.  

     

    Discussion

    Static and dynamic visual acuity was measured on the right eye of emmetropic subjects. Results for SVA showed significantly better resolution in the temporal visual field compared with the nasal visual field at eccentricities 20° and beyond. The mean difference in acuity at 20° was approximately 0.2 LogMAR and at 30°, 0.3 LogMAR. The difference between the thresholds for DVA showed a similar naso-temporal asymmetry; the reduction in DVA paralleling the decrease in SVA for eccentricities 10° and beyond.  No significant differences were observed between averaged results of SVA and DVA for the eccentricities tested in this study.

     

    Conclusions

    The results of this study confirm previous research conducted by Frisén (1987) showing better resolution for static stimuli presented in the temporal visual field compared to the nasal visual field. We have found that this is also true for DVA.

  • 111.
    Lewis, Peter
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosén, Robert
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Unsbo, Peter
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Resolution of static and dynamic stimuli in the peripheral visual field.2011In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 51, no 16, p. 1829-1834Article in journal (Refereed)
    Abstract [en]

    In a clinical setting, emphasis is given to foveal visual function, and tests generally only utilize static stimuli. In this study, we measured static (SVA) and dynamic visual acuity (DVA) in the central and peripheral visual field on healthy, young emmetropic subjects using stationary and drifting Gabor patches. There were no differences between SVA and DVA in the peripheral visual field; however, SVA was superior to DVA in the fovea for both velocities tested. In addition, there was a clear naso-temporal asymmetry for both SVA and DVA for isoeccentric locations in the visual field beyond 10° eccentricity. The lack of difference in visual acuity between static and dynamic stimuli found in this study may reflect the use of drift-motion as opposed to displacement motion used in previous studies.

  • 112.
    Lidén, Maja
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Synfältsundersökningen vid synprövning för körkort hos optiker2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Syftet var att ta reda på vilken metod som är lämpligast att använda för synfältsundersökning vid ett körkortstest hos optiker samt vilken metod det är vanligast att optiker i Sverige använder idag. Dessutom var syftet att utreda varför optiker inte får använda konfrontationstest då det är den metod läkare ska använda för synfältsundersökning enligt körkortsföreskrifterna.

    Metod: En enkätundersökning med 275 deltagande optiker gjordes. De fick besvara ett fåtal frågor kring vilken metod de använder när de undersöker synfältet vid ett körkortstest samt deras kunskap och inställning till bestämmelserna kring vilken metod som skall användas utav optiker och läkare. Enkätundersökningen publicerades med web-enkätprogrammet Easy Survey.

    Resultat: Enkätundersökningen visade att endast 58,5 % av optiker i Sverige använder sig av den speciellt avsedda apparaturen. 34,9 % av deltagarna svarade att de använde sig av Donders konfrontationstest. Undersökningen visade på att många optiker i Sverige inte vet vilken metod de enligt föreskriften från 2008 ska använda. Dessutom visar resultaten att en klar majoritet av dem inte förstår varför inte optiker får använda samma metod som läkare för synfältsundersökning vid ett körkortstest.

    Slutsats: Studien visar att en majoritet av optiker i Sverige använder den av myndigheten rekommenderade metoden men att många också använder Donders. Ett konfrontationstest borde vara mer lämpligt att använda för att undersöka synfältet vid en synprövning för körkort hos optiker än en synfältsapparat. Optiker har tillräckligt stor kunskap för att klara av att använda Donders konfrontationstest och när det utförs korrekt verkar det vara mer tillförlitligt än en apparatur så som Campitestet, då det undersöker synfältet mer utförligt.

  • 113.
    Liljenberg, Anna
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Antioxidanter förhindrar AMD: Sanning eller myt?2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Att undersöka ifall ett ökat intag av antioxidanter via kost eller supplement kan förhindra uppkomst och progression av åldersrelaterad makuladegeneration, AMD.

    Metod: Granskning och sammanställning av publicerade forskningsresultat inom området.

    Resultat: Av 7 granskade studier visade 5 på en skyddande effekt mot uppkomst eller progression av AMD vid ett ökat intag av antioxidanter. Resterande 2 studier kunde inte finna något signifikant samband. Resultatet varierar för specifika antioxidativa ämnen i olika studier.

    Slutsats: Forskningen tyder på att ett ökat intag av antioxidanter, antingen via kosten eller supplement, skulle kunna förebygga och bromsa de skador som uppkommer vid AMD. Man bör dock ytterligare utreda eventuella negativa bieffekter vid höga doser av bland annat β-karoten och E-vitamin. Det behövs fler långtidsstudier för att fullt ut förstå samspelet mellan hur olika livsmedel och specifika antioxidanter tas upp och metaboliseras och hur dessa kan påverka uppkomst och progression av AMD.

  • 114.
    Lima Ramos, Pedro
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portugal.
    Santana, Rui
    Univ Nova Lisboa, Portugal.
    Moreno, Laura Hernandez
    Univ Minho, Portugal.
    Marques, Ana Patricia
    Univ Nova Lisboa, Portugal.
    Freitas, Cristina
    Hosp Braga, Portugal.
    Rocha-Sousa, Amandio
    Univ Porto, Portugal;Ctr Hosp Sao Joao, Portugal.
    Macedo, António Filipe
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portugal.
    ., The Portuguese visual impairment study group
    Predicting participation of people with impaired vision in epidemiological studies2018In: BMC Ophthalmology, ISSN 1471-2415, E-ISSN 1471-2415, Vol. 18, article id 236Article in journal (Refereed)
    Abstract [en]

    Background

    The characteristics of the target group and the design of an epidemiologic study, in particular the recruiting methods, can influence participation. People with vision impairment have unique characteristics because those invited are often elderly and totally or partially dependent on help to complete daily activities such as travelling to study sites. Therefore, participation of people with impaired vision in studies is less predictable than predicting participation for the general population.

    Methods

    Participants were recruited in the context of a study of prevalence and costs of visual impairment in Portugal (PCVIP-study). Participants were recruited from 4 Portuguese public hospitals. Inclusion criteria were: acuity in the better eye from 0.5 decimal (0.30logMAR) or worse and/or visual field of less than 20 degrees. Recruitment involved sending invitation letters and follow-up phone calls. A multiple logistic regression model was used to assess determinants of participation. The J48 classifier, chi-square and Fisher’s exact tests were applied to investigate the possible differences between subjects in our sample.

    Results

    Individual cases were divided into 3 groups: immediate, late and non-participants. A participation rate of 20% was obtained (15% immediate, 5% late). Factors positively associated with participation included years of education, annual hospital attendance, and intermediate visual acuity. Females and greater distance to the hospital were inversely associated with participation.

    Conclusion

    In our study, a letter followed by a phone call was efficient to recruit a significant number of participants from a larger group of people with impaired vision. However, the improvement in participation observed after the phone call might not be cost-effective. People with low levels of education and women were more difficult to recruit. These findings need to be considered to avoid studies whose results are biased by gender or socio-economic inequalities of their participants. Young subjects and those at intermediate stages of vision impairment, or equivalent conditions, may need more persuasion than other profiles.

  • 115.
    Lima Ramos, Pedro
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portugal.
    Santana, Rui
    Univ Nova Lisboa, Portugal.
    Sousa, Ines
    Univ Minho, Portugal.
    Rocha-Sousa, Amandio A.
    Univ Porto, Portugal.
    Macedo, António Filipe
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portugal.
    Prevalence of Visual Impairment in the Municipality of Braga -Portugal using capture-recapture methods2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal (Other academic)
  • 116.
    Lindberg, Josefin
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Förändrar mjuka kontaktlinser NITBUT?2011Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Det är många som upplever att de får torra ögon vid användning av kontaktlinser. Därför är syftet med denna studie att jämföra NITBUT utan och med kontaktlinser för att undersöka om kontaktlinser påverkar tårfilmsstabiliteten.

    Metod: 30 stycken vana linsbärare deltog i studien. Två mätningar utfördes, en gång på eftermiddagen då försökspersonen varit utan kontaktlinser hela dagen och en då de använt sina habituella kontaktlinser i minst sex timmar. NITBUT mättes indirekt med hjälp av Tearscope-plus och ett fint gitter. Det gjordes tre mätningar per öga där ett medelvärde sedan räknades ut.

    Resultat: Det var ingen signifikant skillnad (p > 0,05) mellan höger och vänster ögas mätningar. Höger ögas mätningar analyserades och visade en signifikant skillnad (p < 0,05) mellan NITBUT utan och med kontaktlinser. Deltagarna delades in i två grupper ena gruppen där NITBUT < 10 sekunder och den andra > 10 sekunder utan kontaktlinser. Den nya indelningen analyserades och det visade att hos gruppen med NITBUT <10 sekunder var skillnaden mellan utan och med kontaktlinser inte statistisk signifikant (p > 0,05) medan det i den andra gruppen med NITBUT > 10 sekunder fanns en statistisk signifikans (p < 0,05) mellan utan och med kontaktlinser.

    Slutsats: Studien kom fram till att kontaktlinser påverkar tårfilmsstabiliteten negativt. När NITBUT < 10 sekunder utan kontaktlinser påverkar kontaktlinsen inte NITBUT medan när NITBUT > 10 sekunder utan kontaktlinser kommer NITBUT att sänkas dramatiskt efter sex timmars användning av kontaktlinser och till och med hamna under gränsvärdet för torra ögon (NITBUT < 10 sekunder).

  • 117.
    Lindquist, Jennifer
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Utfall av tre olika formler för beräkning av postoperativ refraktion vid kataraktkirurgi2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    ABSTRAKT

    Vid kataraktkirurgi är det viktigt att med stor noggrannhet kunna beräkna ögats postoperativa refraktion. För detta finns det flera olika biometriformler, varav SRK/T, Haigis och Hoffer Q har ingått i denna studie.

    Syfte: Att jämföra hur de tre formlerna presterar i genomsnitt när man jämför den beräknade postoperativa refraktionen med det verkliga utfallet, samt att se om det finns någon skillnad i utfallet i relation till ögats axiallängd.

    Metod: Data från 81 ögon erhölls från ögonkliniken i Kalmar. Alla var uppmätta med IOLMaster och hade genomgått fakoemulsifikation. Den vikbara intraokulära lins som användes var Alcons Acrysof SN60WF. Data från biometrin sattes in i var och en av de tre formlerna och beräknad postoperativ refraktion jämfördes sedan med verklig. SRK/T och Hoffer Q hade optimerade konstanter, medan Haigis tre konstanter hämtats ur publicerat material. Jämförelse gjordes även för ögon med axiallängd kortare än 22 mm och längre än 25 mm.

    Resultat: Ingen statistiskt signifikant skillnad i utfall mellan SRK/T, Haigis och Hoffer Q fanns generellt sett. I relation till axiallängden fanns en tendens att Hoffer Q påverkas något. För ögon längre än 25 mm fanns heller ingen statistiskt signifikant skillnad mellan de tre formlerna. I gruppen med ögon kortare än 22 mm fanns det en statistiskt signifikant skillnad mellan SRK/T och Hoffer Q respektive Haigis och Hoffer Q. Dock var urvalet av korta och långa ögon så litet att någon slutsats inte kunde dras av detta.

    Slutsats: Studien visar att det inte finns någon statistiskt signifikant skillnad mellan hur SRK/T, Haigis och Hoffer Q presterar i genomsnitt. Inte heller i relation till olika axiallängder kan man se någon direkt skillnad mellan formlerna.

    Det verkar sannolikt att Haigis formel kommer att kunna prestera ännu bättre när dess konstanter optimerats.

  • 118.
    Lundström, Emma
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Short-term effects on contrast sensitivity and its correlation to over-refraction when using MiSight®1day contact lenses2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 119.
    Lundström, Linda
    et al.
    Royal Institute of Technology.
    Venkataraman, Abinaya Priya
    Royal Institute of Technology.
    Lewis, Peter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Unsbo, Peter
    Royal Institute of Technology.
    Spatiotemporal contrast sensitivity in the 10 degrees visual field2016In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 57, no 12Article in journal (Refereed)
  • 120.
    Macedo, António Filipe
    et al.
    Universty of Minho, Portugal.
    Borges Ferreira, Marisa
    TEM-All with the Mutiple Sclerosis, Portugal ; Universty of Minho, Portugal.
    Parreira, Marta Gamito
    TEM-All with the Mutiple Sclerosis, Portugal.
    Sousa, Inês
    Universty of Minho, Portugal.
    Figueiredo, José
    Private Hospital of Braga, Portugal.
    Cerqueira, João José
    University of Minho, Portugal ; Hospital de Braga, Portugal.
    Silva Pereira, Paulo
    University of Minho, Portugal.
    Anti-saccades in early stages of multiple sclerosis2015In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, no 7, article id 2911Article in journal (Refereed)
    Abstract [en]

    Purpose: Eye movements disability is common finding in multiple sclerosis (MS) but the exact stage at which changes are visible is not clear. The aim of study was to assess if anti-saccade (AS) planning and execution are altered at early stages of the disease.

    Methods: A total of 48 participants with MS selected by a neurologist (JJC) at Hospital de Braga and 52 controls participated in this study. Inclusion criteria: relapsing-remitting course, EDSS≤3, 1 month or more without MS crisis, and normal or corrected visual acuity. Exclusion criteria (MS and Control): cognitive impairment, traumatic brain injury or stroke. The mean age in the MS group was 37y and 33y in the control group. Eye movements were monitored using a binocular infrared eyetracker running at 250Hz(RED250, SMI Gmb Germany), precision <0.4deg, stimuli were presented in a 22 monitor (Dell P2210). Code for running the experiment and data analysis was written using the Matlab (Mathworks Inc). Participants were seated in a room dim light at 74cm from the monitor and head movements were minimized by a headband. The task was to fixate, after a variable period between steady fixation and the stimulus of 1250ms or 1600ms, participants looked as quickly as possible for the opposite direction where the target (a 30x30mm cross) was presented (anti-saccade movement). Each subject performed 40 trails.

    Results: The main results were the proportion of the directional errors (wherein the participant voluntarily looked for the wrong side), and latencies for: i) anti-saccades, ii) pro-saccades (movement in the same direction of the stimulus) and iii) correction (reaction time that the participant takes from the error fixation until to start the movement). The mean number of errors was 28%(SD=19) in MS group and 16%(SD=11) in the control group, mean difference 12%, t(74)=3.83, p<.001. Anti-saccades latency was 330msec (SD=61) in the MS group and 294ms(SD=59) in the control group, mean difference 36ms, F(1,98)=10.99, p<.05. The mean of the correction latency value was 178ms(SD=111) in the MS group and 129ms(SD=107) in the control group with a mean difference of 49ms, F(1,98)=6, p<.05. No statistically significant differences were found in accuracy and pro-saccade latency between groups.

    Conclusions: This study shows that anti-saccades latency and errors are increased at early stages of multiple sclerosis. Anti-saccades might be a sensitive tool to assess functional status in people with this condition.

  • 121.
    Macedo, António Filipe
    et al.
    UCL Institute of Ophthalmology, UK ; University of Minho, Portugal.
    Crossland, M. D.
    UCL Institute of Ophthalmology, UK.
    Rubin, G. S.
    UCL Institute of Ophthalmology, UK ; NIHR Faculty, UK.
    The effect of retinal image slip on peripheral visual acuity2008In: Journal of Vision, ISSN 1534-7362, E-ISSN 1534-7362, Vol. 8, no 14, p. 1-11, article id 16Article in journal (Refereed)
    Abstract [en]

    Abstract Retinal image slip promoted by fixational eye movements prevents image fading in central vision. However, in the periphery a higher amount of movement is necessary to prevent this fading. We assessed the effect of different levels of retinal image slip in peripheral vision by measuring peripheral visual acuity (VA), with and without crowding, while modulating retinal image slip by using gaze-linked stimuli. Measurements were carried out at four isoeccentric positions at 5 and at 10 degrees eccentricity. Gaze position was monitored throughout using an infrared eyetracker. The target was presented for up to 500 msec, either with no retinal image slip, with reduced retinal slip, or with increased retinal image slip. Without crowding, peripheral visual acuity improved with increased retinal image slip compared with the other two conditions. In contrast to the previous result, under crowded conditions, peripheral visual acuity decreased markedly with increased retinal image slip. Therefore, the effects of increased retinal image slip are different for simple (noncrowded) and more complex (crowded) visual tasks. These results provide further evidence for the importance of fixation stability on complex visual tasks when using the peripheral retina.

  • 122.
    Macedo, António Filipe
    et al.
    UCL Institute of Ophthalmology, UK ; University of Minho, Portugal.
    Crossland, Michael D.
    UCL Institute of Ophthalmology, UK ; NIHR Biomedical Research Centre for Ophthalmology, UK.
    Rubin, Gary S.
    UCL Institute of Ophthalmology, UK ; NIHR Biomedical Research Centre for Ophthalmology, UK.
    Investigating unstable fixation in patients with macular disease2011In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 52, no 3, p. 1275-1280Article in journal (Refereed)
    Abstract [en]

    Purpose.: To assess the effect on visual acuity of compensating fixation instability by controlling retinal image motion in people with macular disease.

    Methods.: Ten patients with macular disease participated in this study. Crowded and noncrowded visual acuity were measured using an eye tracking system to compensate for fixation instability. Four conditions, corresponding to four levels of retinal image motion, were tested: no compensation (normal motion), partial compensation (reduced motion), total compensation (no motion), and overcompensation (increased motion). Fixation stability and the number of preferred retinal loci were also measured.

    Results.: Modulating retinal image motion had the same effect on crowded and noncrowded visual acuity (P = 0.601). When fixation instability was overcompensated, acuity worsened by 0.1 logMAR units (P < 0.001) compared with baseline (no compensation) and remained equal to baseline for all other conditions.

    Conclusions.: In people with macular disease, retinal image motion caused by fixation instability does not reduce either crowded or noncrowded visual acuity. Acuity declines when fixation instability is overcompensated, showing limited tolerance to increased retinal image motion. The results provide evidence that fixation instability does not improve visual acuity and may be a consequence of poor oculomotor control.

  • 123.
    Macedo, António Filipe
    et al.
    University of Minho, Portugal.
    Encarnacao, Tito J.
    University of Minho, Portugal.
    Baptista, Antonio M.
    University of Minho, Portugal.
    Temporal Processing in the Peripheral Retina2012In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 53, no 14, article id 4830Article in journal (Refereed)
    Abstract [en]

    Purpose: There is an increasing number of reports in the literature about the possible influence of the peripheral refraction in myopia development. The aim of this work was to determine whether the peripheral refractive differences lead to changes in visual performance. We used a forced choice procedure to assess the speed and accuracy (visual processing) of people with and without myopia at detecting the direction of a Gabor patch presented at different retinal locations.

    Methods: Visual processing was measured twice in random order at 6 retinal locations: 10, 20 and 30 degrees eccentricity at the temporal and at the nasal retina. We tested the dominant eye of 8 adults (aged 19 to 33 years) with moderate myopia (spherical equivalent ranging from -4.25 to -2.00 D) and 8 age-matched adults without myopia (spherical equivalent from -0.63 to 0.75 D). Participants’ task was to report via bottom press whether the Gabor patch, with suprathreshold contrast and spatial frequency, was tilted 30º to the right or to the left. The target was preceded by a 50 msec duration cue, exposed for variable periods of 10, 30, 60, 90 and 140 msec, selected in random order, and followed by a noise mask until response was given. For each block, processing time was determined using the method of constant stimuli based in 400 trials per retinal location (80 trials per exposure). Threshold was defined as the exposure time yielding 75% of correct responses; results were analysed using linear mixed models (SPSS, v18).

    Results: The mean processing time in the group with myopia was 73 msec and in the group without myopia was 66 msec; the difference between groups was not statistically significant (p = 0.087). There was a statistically significant difference between the nasal and temporal retina, mean difference was 13 msec (p = 0.002) with smaller processing time in the nasal retina.

    Conclusions: For the type of paradigm used in this study, there was no difference in processing time of the peripheral retina between people with and people without myopia. Despite extensive reports in the literature about different refraction patterns in this study we found evidences that this does not translate into functional changes.

  • 124.
    Macedo, António Filipe
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. University of Minho, Portugal.
    Encarnação, Tito J.
    Ctr. de Diagnóstico da Visão, Portugal.
    Vilarinho, Daniel
    University of Minho, Portugal.
    Baptista, António M. G.
    University of Minho, Portugal.
    An exploratory study of temporal integration in the peripheral retina of myopes2017In: Proceedings of SPIE 10453, SPIE - International Society for Optical Engineering, 2017, Vol. 10453, article id 104532GConference paper (Refereed)
    Abstract [en]

    The visual system takes time to respond to visual stimuli, neurons need to accumulate information over a time span in order to fire. Visual information perceived by the peripheral retina might be impaired by imperfect peripheral optics leading to myopia development. This study explored the effect of eccentricity, moderate myopia and peripheral refraction in temporal visual integration. Myopes and emmetropes showed similar performance at detecting briefly flashed stimuli in different retinal locations. Our results show evidence that moderate myopes have normal visual integration when refractive errors are corrected with contact lens; however, the tendency to increased temporal integration thresholds observed in myopes deserves further investigation.

  • 125.
    Macedo, António Filipe
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. University of Minho, Portugal.
    Lima Ramos, Pedro
    University of Minho, Portugal.
    Hernandez-Moreno, Laura
    University of Minho, Portugal.
    Cima, Joana
    Nova University of Lisbon, Portugal.
    Baptista, António M. G.
    University of Minho, Portugal.
    Marques, Ana Patricia
    Nova University of Lisbon, Portugal.
    Massof, Robert
    Johns Hopkins Wilmer Eye Institute, USA.
    Santana, Rui
    Nova University of Lisbon, Portugal.
    Visual and health outcomes, measured with the activity inventory and the EQ-5D, in visual impairment2017In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 95, no 8, p. e783-e791Article in journal (Refereed)
    Abstract [en]

    Purpose

    Generic instruments to assess health utilities can be used to express the burden of health problems in widely used indexes. That is in contrast with what can be obtained with condition-specific instruments, outcomes are very specific and difficult to compare across conditions. The purpose of this study was to assess health and visual outcomes and its determinants in patients with visual impairment (VI) using the EQ-5D-3L and the Activity Inventory (AI).

    Methods

    Participants were recruited in different hospitals during the PCVIP-study. A total of 134 patients with acuity 0.30 logMAR or less in the better eye were interviewed. The AI includes 46 goals split between three objectives: social functioning, recreation and daily living, and was used to measure visual ability. The EQ-5D consists of five questions covering one domain each and was used to provide a measure of health states. Responses to each domain were combined to produce a single individual index.

    Results

    The AI and the EQ-5D-3L showed enough discriminatory power between VI levels (p < 0.001), and their results were strongly correlated r(134) = 0.825, (p < 0.001). Explanatory factors for visual ability were level of VI in better eye, age and gender, R2 = 0.43, (p < 0.001). Explanatory factors for the EQ-5D-3L were level of VI in the better eye, comorbidities and gender, R2 = 0.36, (p < 0.001).

    Conclusion

    Our results showed that the EQ-5D-3L is useful when characterizing the burden of VI and to compute, when necessary, quality-adjusted-life-years (QALY) changes due to VI. However, it is important to consider that the EQ-5D-3L uses a coarse response scale, assesses a limited spectrum of domains and is influenced by comorbidities. This might limit its responsiveness to small changes in visual ability.

  • 126.
    Macedo, António Filipe
    et al.
    University of Minho, Portugal.
    Moreno, Laura H.
    University of Minho, Portugal.
    Silva, Rui S.
    University of Minho, Portugal.
    Crossland, Michael D.
    Anglia Ruskin University, UK ; Moorfields Eye Hospital NHS Foundation Trust, UK.
    Smartphones in visual impairment2014In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, no 13, article id 4150Article in journal (Refereed)
    Abstract [en]

    Purpose 

    We have previously shown that electronic devices can be used by people with relatively low visual acuity and contrast sensitivity. The aim of this study was to determine if people with visual impairment use smartphones to compensate their visual deficits.

    Methods 

    An online survey was advertised to people with visual impairment using personal contacts, social media and online discussion groups. This survey was administered in two languages: English and Portuguese. The first author is fluent in both languages and ensured accurate translation. The questionnaire was designed to collect basic demographic information and self-reported cause of visual impairment. Participants were asked to specify whether they used smartphones, and if so which operating system they used, what they used the device for, and which accessibility functions they used.

    Results 

    In total 131 responses were obtained: 75 to the English and 56 to the Portuguese survey. 93% of the respondents were younger than 64 years and 25% had no perception of light. From the total number of 131 respondents, 101 used smartphone. Of these, 57% used an Apple OS, 22% used Android and 15% used Symbian. 98% of smartphone users made phone calls with their device and sending text messages was reported by 93%. Internet navigation was used by 84%, photo capabilities were used by 53% to help them to see and by 73% for other purposes. 80% also used apps on their device. Speech navigation was used by 67% of respondents, ability to enlarge print was used by 58% and a large screen was important to 40%. Font type and contrast changes were less commonly used. Only 14% received information about these devices from a vision care professional. Other sources included online search, recommendations from friends or blind associations.

    Conclusions 

    Smartphones are widely used by people with visual impairment. The current accessibility features such as speech navigation and large print allow people with visual impairment to use of these devices not only as phones but also as an electronic low vision aid.

  • 127.
    Macedo, António Filipe
    et al.
    University of Minho, Portugal.
    Nascimento, Sérgio Miguel Cardoso
    University of Minho, Portugal.
    Gomes, Augusto Oliveira Silva
    University of Porto, Portugal.
    Puga, André Texieira
    University of Porto, Portugal.
    Fixation in Patients with Juvenile Macular Disease2007In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 84, no 9, p. 852-858Article in journal (Refereed)
    Abstract [en]

    Purpose. The instability of fixation with central scotoma has been mainly studied in patients with age-related macular diseases (MDs). However, early macular lesions can lead to different characteristics of fixation. The aim of this work was to study fixation in patients with juvenile MD.

    Methods. Eye movements of 10 patients and 10 controls were monitored during fixation. Visual fields were assessed by static perimetry to determine the extent of the field defects. Eye movements were separated into saccades and drifts, with fixation stability assessed by bivariate contour ellipse area (BCEA). To quantify the number and location of preferred retinal loci (PRL), the kernel density estimator and expectation maximization for mixtures of gaussians were used.

    Results. Patients have worse fixation stability than controls and large BCEAs resulted in more than one PRL. It was found that central field defects (10°) have negative correlation with the size of BCEA. In addition, the meridian of saccades during fixation was correlated with the meridian inter-PRL.

    Conclusions. Patients with juvenile MDs have large BCEAs, frequently associated with two PRL. Similar results had been found for patients with age-related MDs. Also, the meridian of involuntary saccades during fixation was found to be correlated with the location of PRLs, suggesting a useful role of these movements in alternating between them.

  • 128.
    Macedo, António Filipe
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portugal.
    Santos, Diana
    Univ Minho, Portugal.
    Hernandez-Moreno, Laura
    Univ Minho, Portugal.
    Leitao, Marta
    Univ Minho, Portugal.
    Latham, Keziah
    Anglia Ruskin Univ, UK.
    Linhares, Joao
    Univ Minho, Portugal.
    Exploring barriers to physical activity faced by people with vision loss2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal (Other academic)
  • 129.
    Magnusson, Linus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    En Jämförelse av Olika Studier på Visus- och K-värdeförändringar vid Ortokeratologibehandling2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Bakgrund: Ortokeratologi är en teknik där man genom specialdesignade RGP-linser kan reducera eller helt eliminera låg och måttlig myopi och även låggradig hyperopi och astigmatism. Man sover med linserna under natten, tar ut dem på morgonen och kan sedan gå utan glasögon och kontaktlinser hela dagen med bra visus. I denna studie tas en del fakta upp om hur ortokeratologi fungerar och på vilka tekniken fungerar.

    Syfte: Syftet vara att ta reda på mera om ortokeratologi då detta är en teknik på framfart. Även att jämföra undertecknads prövotid med redan gjorda studier.

    Metod: I studien jämfördes en försöksperson med tidigare gjorda studier, försökspersonen använde ortokeratologilinser under 45 dagar och mätningar som togs och jämfördes var k-värde (corneas kurvatur) och fri visus (synskärpa). Mätningarna utfördes dag 1, 3, 7 och 14, sedan togs visus 1 gång i veckan för att kontrollera att den hölls stabil.

    Resultat: visade att samtliga studier hade ungefär samma resultat där nästan alla försökspersoner fick bra visus under behandlingen. På försökspersonen i denna studie fungerade det också bra förutom lite inducerad astigmatism av linserna och halofenomen.

    Slutsats: ortokeratologi är en väl fungerande metod om endast rätt patienter som ligger inom gränserna av synfel används. Den kräver dock mer arbete än en vanlig linstillpassning, både från tillpassaren genom täta återbesök och från patienten genom att compliance och linsskötsel är väldigt viktigt.

    2008:O24

  • 130.
    Malm, Maria
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Färguppfattning genom Multilens färgade filter2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Aim: The aim of this study was to see if there would be any difference in color vision perception between two different Multilens prototype filter-lenses product for people with color vision deficiencies in the red-green spectrum. The filters were also tested in normal individuals who acted like as controls.

    Methods: 32 people participated in this study. 13 had a color vision deficiency in the red-green spectrum and 19 of them had normal color vision. Two of Multilens new filter-lens prototypes, filter B and filter D, was tested against no filter. Instrument used was the Cambridge Research System´s Metropsis. The test for measurements was CCT-Ellipse 10a, which presented results in terms of ellipses. The necessary values were analysed by Friedman test.

    Results: Multilens filter-lenses gave a significant change in color perception for both subjects with normal- or deficient color vision. A significant change in color vision between filter B and filter D was shown for those with normal color vision. Subjects with deficient color vision only experienced a significant change with filter D. The subjective impression of the filter-lenses was generally positive for those with deficient color vision.

    Conclusion: Filter B and D gives an improvement on color vision for some of the participants but is not statistically significant. All participants experienced changed color vision, but when a specific hue became easier to see, other hues became more difficult to see. Subjectively, some of the participants with color deficiency saw a big positive difference between with and without the filter-lenses.

  • 131.
    Marques, Ana Patricia
    et al.
    NOVA University of Lisbon, Portugal.
    Macedo, António Filipe
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. University of Minho Braga, Portugal.
    Lima Ramos, Pedro
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. University of Minho Braga, Portugal.
    Moreno, Laura Hernandez
    University of Minho Braga, Portugal.
    Butt, Thomas
    Peking University, Peoples Republic of China;University College London, UK.
    Rubin, Gary
    University College London, UK.
    Santana, Rui Santana
    NOVA University of Lisbon, Portugal.
    Productivity Losses and Their Explanatory Factors Amongst People with Impaired Vision2019In: Ophthalmic Epidemiology, ISSN 0928-6586, E-ISSN 1744-5086, p. 1-15Article in journal (Refereed)
    Abstract [en]

    Purpose: To estimate productivity losses amongst people with impaired vision in Portugal and to investigate explanatory factors associated with non-participation in the labour market.

    Methods: A total of 546 visually impaired individuals participated in face-to-face interviews. Participants were asked about their workforce participation to determine productivity (employment status questionnaire), their health-related quality of life – HRQoL (EQ-5D) and their visual acuity and visual ability (Activity Inventory). Productivity losses included absenteeism and reduction in workforce participation. Logistic regression was used to determine independent factors associated with participation in the labour market.

    Results: From the 546 participants, 50% were retired, 47% were of working age and 3% were students. The employment rate was 28%, and the unemployment rate was 21% for the working age sample. For those of working age, productivity losses were estimated at €1.51 million per year, mean of €5496 per participant. The largest contributor to productivity losses was reduced workforce participation, estimated from 159 early retired or unemployed participants. After controlling for visual acuity and ability, younger individuals, with more years of education, without comorbidities and high HRQoL had a higher probability of being employed.

    Conclusions: Our findings show a high unemployment rate and high productivity losses amongst people with impaired vision. The probability of being employed was associated with education, HRQoL and comorbidities. We speculate that promoting education and health through effective visual rehabilitation programs may help to increase participation in the labour market. These findings can inform decisions to intervene to reduce the burden of vision loss.

  • 132.
    Marques, Ana Patricia
    et al.
    Nova University of Lisbon, Portugal.
    Macedo, António Filipe
    University of Minho, Portugal.
    Rocha-Sousa, Amandio A.
    Unversity of Porto, Portugal.
    Baptista, Antonio M. G.
    University of Minho, Portugal.
    Rubin, Gary S.
    UCL-Institute of Ophthalmology, UK.
    Monteiro, Joel
    Centro Hospitalar do Alto Ave, Portugal.
    Hernández-Moreno, Laura
    University of Minho, Portugal.
    Cima, Joana
    Nova University of Lisbon, Portugal.
    Santana, Rui
    Nova University of Lisbon, Portugal.
    Estimating the cost of visual impairment: initial results2015In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, no 7, article id 2134Article in journal (Refereed)
    Abstract [en]

    Purpose: Vision loss can have a substantial human and economic impact on individuals and society that include disability, loss of productivity and reduction in quality of life. The purpose of this study was to estimate economic burden of visual impairment in Portugal.

    Methods: A prevalence-based cost of illness approach was adopted to estimate costs of vision impairment. We estimated direct medical costs and indirect economic costs. Direct medical hospital costs were determined using a bottom up approach. For those meeting the inclusion criteria (visual acuity of 20/40 or 0.5decimal or worse in the better eye and/or visual field of less than 20deg) we estimated direct costs by collecting information from administrative records that included: physician’s office visits, emergency and outpatient visits. We developed a survey based in parts of the annotated cost questionnaire-HERU Discussion Paper N.03/01 (UK Working Party on Patient Costs) and the Service Receipt Inventory-European Version. Using the questionnaire that we developed, in face-to-face interviews, we collect direct medical expenditures supported by patients that included: costs with medical prescriptions, low vision aids and devices. With the same questionnaire we collected information for indirect costs calculations. Indirect costs were calculated by estimating the value of productivity losses including employment participation, absenteeism and caregiver costs.

    Results: Results presented here correspond to 442 patients that met the inclusion criteria. The four main causes of visual impairment in this sample were Diabetic Retinopathy, Cataract, Glaucoma and Age-related macular degeneration. Direct medical hospital costs were accountable for 12% of total costs calculated. Patient expenditures represented 25% of expenses with visual impairment and indirect costs corresponded to 63% of the total. From this data we estimated that the average annual direct cost per patient with VI was 958 euro and average annual indirect cost was 1655 euro.

    Conclusions: With the instruments and methodology that was adopted we were able quantify direct medical hospital costs as well as indirect costs of visual impairment. Results of this study show that more than half of the costs with VI are indirect. This highlights that particular attention should be given to costs that arise for individuals with vision loss.

  • 133.
    Marques, Ana Patricia
    et al.
    Nova University of Lisbon, Portugal.
    Macedo, António Filipe
    University of Minho, Portugal.
    Rocha-Sousa, Amandio A.
    University of Porto, Portugal.
    Perelman, Julian
    Nova University of Lisbon, Portugal.
    Baptista, António M.
    University of Minho, Portugal.
    Santana, Rui
    Nova University of Lisbon, Portugal.
    Emergence of intravitreal injections in a National Health System: 2002-20122014In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, no 13, article id 6088Article in journal (Refereed)
    Abstract [en]

    Purpose 

    Intravitreal injections of antivascular endothelial growth factor (anti-VEGF) are an innovative procedure with well-proven benefits to preserve vision in certain eye conditions. The aim of this study was to examine the diffusion of this treatment in the Portuguese National Health System.

    Methods 

    We used a database of all in-patient and day cases stays from all Portuguese public hospitals during period 2002-2012. We selected cases based on four procedures, ICD-9-CM codes: 1414, 1475, 1479, 149. Given that these procedures are not specific for intravitreal injections it is likely that our results captured cases that are not anti-VEGF injections. Because we were only interested in the diffusion of new anti-VEGF treatments we included years 2002-2005 as baseline because during that period drugs anti-VEGF were not licenced. We calculated absolute values, yearly rates of episodes and rates of patients treated per 100,000 habitants.

    Results 

    Our final sample included 98,408 episodes, 52% performed in men. The total number of episodes increased from 1,815 in 2002 to 25,106 in 2012 (mean annual increase of 32%). These values corresponded to an increase in ratios per 100,000 from 17.4 to 238.77. The highest increase was observed between 2007 and 2009 with an increase of 337%. The number of treated patients was six times higher in 2012 with 11,937 treated compared with 1,561 in 2002 (mean annual increase of 24%). The highest increase was also observed between 2006 and 2009. In 2012, 86.2% of the procedures were performed as day cases, representing an increase of 78.3% as compared to 2002. The percentage of patients older than 60 years increased from 60% in 2002 to 80% in 2012. Five diagnoses (See Figure: wet AMD, diabetic macular oedema, oedema of the retina, retinal neovascularization and non-specific AMD) were associated with 73% of these procedures in 2012, in contrast with only 16% in 2002.

    Conclusions 

    The number of procedures grew exponentially since anti-VGEF treatments were approved. The aging of the population and the expected growth in conditions such as diabetes and AMD are likely to increase the demand for these procedures in years to come. These factors are likely to impose tremendous challenges to health services. That will happen not only due to the price of the procedures but also for number of physicians and other staff needed in Ophthalmology departments.

     View

  • 134.
    Marques, Ana Patrícia
    et al.
    Nova University of Lisbon, Portugal.
    Macedo, António Filipe
    University of Minho, Portugal.
    Perelman, Julian
    Nova University of Lisbon, Portugal.
    Aguiar, Pedro
    Nova University of Lisbon, Portugal.
    Rocha-Sousa, Amândio
    University of Porto, Portugal.
    Santana, Rui
    Nova University of Lisbon, Portugal.
    Diffusion of anti-VEGF injections in the Portuguese National Health System2015In: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 5, no 11, p. 11-Article in journal (Refereed)
    Abstract [en]

    Objectives

    To analyse the temporal and geographical diffusion of antivascular endothelial growth factor (anti-VEGF) interventions, and its determinants in a National Health System (NHS).

    Setting

    NHS Portuguese hospitals.

    Participants

    All inpatient and day cases related to eye diseases at all Portuguese public hospitals for the period 2002–2012 were selected on the basis of four International Classification of Diseases 9th revision, Clinical Modification (ICD-9-CM) codes for procedures: 1474, 1475, 1479 and 149.

    Primary and secondary outcome measures

    We measured anti-VEGF treatment rates by year and county. The determinants of the geographical diffusion were investigated using generalised linear modelling.

    Results

    We analysed all hospital discharges from all NHS hospitals in Portugal (98 408 hospital discharges corresponding to 57 984 patients). National rates of hospitals episodes for the codes for procedures used were low before anti-VEGF approval in 2007 (less than 12% of hospital discharges). Between 2007 and 2012, the rates of hospital episodes related to the introduction of anti-VEGF injections increased by 27% per year. Patients from areas without ophthalmology departments received fewer treatments than those from areas with ophthalmology departments. The availability of an ophthalmology department in the county increased the rates of hospital episodes by 243%, and a 100-persons greater density per km2 raised the rates by 11%.

    Conclusions

    Our study shows a large but unequal diffusion of anti-VEGF treatments despite the universal coverage and very low copayments. The technological innovation in ophthalmology may thus produce unexpected inequalities related to financial constraints unless the implementation of innovative techniques is planned and regulated

  • 135.
    Marques, Dora Nazaré
    et al.
    University of Minho, Portugal.
    Macedo, António Filipe
    University of Minho, Portugal.
    Perceptions of acceptable conducts by university students: [Percepciones sobre las conductas aceptables por los estudiantes universitarios]2016In: Journal of Optometry, ISSN 1888-4296, Vol. 9, no 3, p. 166-174Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: 

    To determine perceptions of acceptable conducts amongst under and postgraduate optometry students and to compare them with students from other disciplines.

    METHODS: 

    Students (under/postgraduate) of optometry (n=156) and other courses (n=54) from University of Minho participated in a voluntary online questionnaire about perception of conducts, classifying as acceptable or unacceptable 15 academic or professional scenarios.

    RESULTS: 

    210 questionnaires were analyzed. Differences in perceptions were found between optometry under and postgraduates in scenario 5, Chi-square(2,156)=4.3, p=0.038, and scenario 7, Chi-square(2,156)=7.0, p=0.008 (both with cheating more acceptable for postgrads). Differences between under and postgraduates from other courses were found in scenario 9 (taking supplies from classroom more acceptable for undergrads), Chi-square(1,54)=5.0, p=0.025, and scenario 14 (forging a signature more acceptable for postgrads), Chi-square(1,54)=3.9, p=0.046. Differences between optometry and other courses undergraduates were observed in scenario 2 (plagiarism more acceptable for optometry undergrads), Chi-square(1,154)=8.3, p=0.004 and scenario 9 (taking supplies from classroom more acceptable for other undergrads), chi-square(1,54)=7.8, p=0.005. Differences between optometry and other courses postgraduates were observed in scenario 7, Chi-square(1,56)=5.8, p=0.016, scenario 10 (both with cheating more acceptable for optometry postgrads), chi-square(1,54)=8.1, p=0.004 and scenario 14 (forging a signature more acceptable for other postgrads), Chi-square(1,54)=6.1, p=0.026.

    CONCLUSION: 

    Academic misconducts were mainly considered more acceptable than professional misconducts. Our results show that perceptions of acceptable conducts amongst optometry students are not very different from other students, and, against our initial prediction, do not show a general change in misconduct perception when students become more mature. Universities should pay more attention to this problem and take action.

  • 136.
    Mattsson, Carina
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hur miljövänlig är dagens optikerbutik, och hur miljövänlig kan den bli?2008Independent thesis Basic level (degree of Bachelor), 15 points / 22,5 hpStudent thesis
    Abstract [en]

    SUMMARY

    Environmental issues are currently a hot topic of debate. Studies within the optics branch have not specifically been conducted previously, so the aim of this study was to determine the extent of environmental-awareness specifically within this branch.

    A survey, consisting of questions relating to environmental issues, was distributed to 100 randomly-selected opticians in Sweden. Of these 100 surveys, 64 were returned and showed a varied branch-engagement for environmental issues.

    Results of this survey showed that opticians were best in sorting newspapers, magazines, other paper and hazardous waste. Metal and rigid plastic were not sorted to any larger extent.

    Choosing environmentally-safe products was not so popular and only six stores always do this. 25 shops turn off electrical machines and equipment over night; while the majority of the remaining stores leave the machines on during the night.

    27 stores did not know if their electrical company provided “green electricity”.

    Results showed that there is a lot of work to be done in making the stores more environmentally friendly. Changes do not have to be great, however all changes can help protect the environment and even result in economic benefits for a practice.

    • Choose electrical-companies that provide “green electricity”

    • Sort garbage better

    • Create an environmental policy in the practice

    • Discuss environmental issues with suppliers

    • Request environmentally-safe products from suppliers

    • Choose environmentally safe products as much as possible

    • Try to think about the environment when travelling or commuting

    • Turn off all electrical machines when not in use

    • Don’t waste water, electricity, chemicals, paper etc.

    • Get information and get environmentally active

  • 137.
    Medina Asencio, Andrea
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Relationen mellan synförmågan och läs- och skrivutvecklingen hos barn2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Att utreda förekomsten av ögonrelaterade läs-och skrivsvårigheter hos skolbarn.

    Metod: Studien bestod av en enkät med ögonrelaterade frågor, ett läsförmågetest och kliniska tester. 45 barn i årskurs 5 och 6 deltog från en mellanstadieskola i Växjö. De kliniska testerna bestod av fri synskärpa på avstånd och nära, +1-metoden för utredning av dold hyperopi, forier på nära håll, ackommodations amplitud, konvergens närpunkt, stereotest och ögonmotilitet. Läsförmågan undersöktes med ett screeningstest så kallade Läskedjor, ett test för att bedöma elevernas lästekniska förmåga, ordigenkänning samt ordavkodning.

    Resultat: En signifikant korrelation hittades mellan bokstavskedjor och ordkedjor (r = 0,4 , p < 0,05). Eleverna ansåg sig inte ha ögonbesvär. En jämförelse mellan Läskedjor och ögonbesvär visade en signifikant korrelation hos ordkedjor (r=0,44 , p < 0,05) men inte hos bokstavskedjor (r=0,083 , p=0,6). Det framgick att större delen av eleverna hade en esofori (35%) samt en ortofori (56%) på nära håll. Inga signifikanta värden hittades mellan Läskedjor och forier (ordkedjor; r=0,05 , bokstavskedjor; r=0,24). Inga signifikanta värden kunde hittas mellan de övriga kliniska testerna med Läskedjor (KNP: bokstavskedjor r=0,004 , ordkedjor: r=0,17 , Ack amplitud: bokstavskedjor: r=0,04 , ordkedjor: r=0,03). I jämförelse med fri synskärpa och +1-metoden visade sig, utifrån medelvärdet, att eleverna är emmetropa samt hyperopa. ANOVA för en faktor visade ingen signifikant skillnad mellan upprepade mätningar av KNP (p=0,4) samt ackommodations amplitud (p=0,8). Medelvärdet för KNP (cm) var 4,17 ± 1,80 och för ackommodations amplitud (D) 15,91 ± 4,38.

    Slutsats: En signifikant relation hittades mellan Bokstavskedjor och Ordkedjor. Ordkedjor är relaterade till ögonbesvär. Ingen relation hittades mellan de kliniska testerna och Läskedjorna.

  • 138.
    Mehretab, Thomas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Structural and functional characteristics of the healthy macula using the OPKO OCT/SLO2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Purpose: To establish normative values for macular light sensitivity in healthy subjects using the OPKO SD-OCT/SLO microperimetry device. This instrument allows direct superimposition of macular function with its structure measured with OCT.  

     

    Methods: 32 normal subjects with mean age of 25 years participated in this study. A 56 point grid covering and area of 18 by 22 degrees of visual field was used. Each subject was tested for the dominant eye. Additional control measures included visual acuity and contrast sensitivity.

     

    Results: The mean (SD) visual acuity in the tested eye was −0.09 (0.088) logMAR. The mean contrast sensitivity in the tested eye was 1.61 (0.102) log contrast. The mean total threshold in the tested eye for all points was 16.60 (1.53) dB. There was a statistically significant correlation between the retinal sensitivity and the total macular thickness, r = −0.392, p-value 0.026 for 48 points per participant.

     

    Conclusions: In this study there was a correlation between the retinal sensitivity and thickness of the macular zone. The values obtained using the microperimetry in undilated eyes was similar to values obtained with dilation. Retinal sensitivity values obtained using this instrument are in agreement with previous studies.

  • 139.
    Meijer, Helena
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    En studie av variationen av upprepade mätningar av tårkvantiteten med Phenol Red Thread Test2011Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Syftet med studien är att genom tre upprepade mätningar av Phenol Red Thread Test(PRT), mäta dess variation i mätvärden. Resultaten från PRT jämförs med symtomenkäten TERTC-DEQ samt TBUT för ytterligare analys av studiens mätdata.

    Metod: 26 personer deltog i studien där PRT mättes vid tre tillfällen med en veckas mellanrum. Alla testobjekt genomgick en undersökning av de främre segmenten i biomikroskop där även Tear Break Up Time (TBUT) med flourescein mättes upp. Vid det första tillfället ombads samtliga testpersoner att fylla i, The Texas Eye Research and Technology Center Dry Eye symptoms Questionnaire (TERTC-DEQ), en symtomenkät som berör upplevda symtom under den senaste veckan.

    Resultat: Studien visade en liten variation mellan mättillfällena. Enligt PRT´s gränsvärden var det 4 personer med måttligt torra ögon och 22 personer med normala ögon. Ingen testperson i studien hade ett medelvärde som indikerade svårt torra ögon. Resultaten från TERTC-DEQ stämde väl överrens med gränsvärdena för PRT. Inget samband hittades mellan PRT och TBUT.

    Slutsats: Resultatet visade ingen statistisk differens mellan medelvärdena för de tre tillfällena (p ˃ 0,05). Mätvärdena från PRT kan hos vissa individer skilja sig mer åt mellan tillfällena, varpå resultatet av PRT bör räknas som ett medelvärde av uppmätta värden. För en riktig bedömning av torra ögon bör ett flertal aspekter vägas in och specifika metoder användas.

  • 140.
    Melin, Elin
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    En, två, tre eller sex luftpuffar?: En studie om hur medelvärdet för det intraokulära trycket ändras beroende på hur många mätningar som görs med en non-contact tonometer2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Syftet med studien var att ta reda på hur stor skillnad det gör för medelvärdet på det slutgiltiga intraokulära trycket (IOP) då det mäts en, två, tre eller sex gånger med en noncontact tonometer. Syftet var också att komma fram till vilket antal mätningar som borde vara det korrekta.

    Metod: Alla mätningar utfördes med hjälp av Topcons non-contact tonometer CT-80A. Mätningarna upprepades på båda ögonen till dess att sex korrekta värden hade mätts upp. Högerögat mättes alltid först. Alla försökspersoner i studien hade normala IOP-värden. IOP mättes på både höger och vänster öga på 60 försökspersoner i åldern 18-50 år.

    Resultat: Studien visar att medelvärdet för IOP sjunker ju fler mätningar som görs. Medelvärdena (± SD) för mätning 1, 1-2, 1-3 och 1-6 är 15,70 ± 2,81 mmHg, 15,37 ± 2,58 mmHg, 15,14 ± 2,41 mmHg respektive 14,78 ± 2,44 mmHg på högerögonen. Motsvarande värden är 14,43 ± 2,25 mmHg, 14,42 ± 2,15 mmHg, 14,38 ± 2,18 mmHg respektive 14,25 ± 2,21 mmHg på vänsterögonen. Skillnaden mellan medelvärdena är statistiskt signifikanta på högerögat men inte på vänsterögat. Det finns en minskning i IOP-värdet mellan första och andra mätningen på 4 mmHg eller mer, på sju högerögon och två vänsterögon. Vid jämförelse mellan ögonen är skillnaden statistiskt signifikant för den första mätningen och medelvärdet för mätning 1-2, men inte för medelvärdena för mätning 1-3 och 1-6. För att skillnaden mellan ögonen ska vara under 4 mmHg hos alla försökspersoner i studien krävs att minst tre mätningar inkluderas i medelvärdet.

    Slutsats: Eftersom det i vissa fall finns en stor sänkning i IOP mellan första och andra mätningen på högerögat, bör minst två mätningar göras i en screeningsituation. Uppmäts då ett IOP som är minst 3 mmHg lägre än gränsen för ett onormalt IOP så räcker det med dessa två. Är IOP närmare gränsen än så bör minst tre mätningar tas för att se om IOPvärdet förändras. Studien visar även att tre mätningar eliminerar de stora skillnader som uppmätts mellan ögonen hos försökspersonerna. Om första mätningen är mycket högre än övriga, eller om ett så korrekt värde som möjligt eftersträvas, så kan fyra mätningar tas och ett medelvärde beräknas på de tre sista.

  • 141.
    Miranda, Antonio Miguel
    et al.
    University of Minho Braga, Portugal.
    Nunes-Pereira, Eduardo J
    University of Minho Braga, Portugal.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Macedo, António Filipe
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. University of Minho Braga, Portugal.
    Eye movements, convergence distance and pupil-size when reading from smartphone, computer, print and tablet2018In: Scandinavian Journal of Optometry and Visual Science, ISSN 1891-0882, E-ISSN 1891-0890, Vol. 11, no 1, p. 1-5Article in journal (Refereed)
    Abstract [en]

    This study investigated the use of eye-tracking glasses to monitor visual behaviour when reading from electronic devices and paper in free-viewing conditions. The Tobii-Pro-Glasses were used to monitor 20 subjects with normal vision during reading tasks. Reading was performed in a smartphone, computer, paper and tablet. Texts from the IReST-test were read in devices in a random order. Participants read one text in each device and then repeated the same task 1 hour later; in total each participant read eight different texts. The sequence for the devices was randomized. We found differences between devices for saccade amplitude, fixation duration, convergence distance and pupil size. Reading speed between computer and tablet was slightly different (8 words-per-minute) and pupil size reduced up to 20% in electronic devices compared to print. Behavioural changes observed whilst reading from different devices may reflect an attempt from readers to optimize performance. The need to maintain visual performance under different visual condition may lead to increased visual symptoms. Eye-tracking glasses could be a valuable tool to investigate visual aspects of digital strain.

  • 142.
    Mohlin, Camilla
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Evaluation of Congo red fluorescence in degenerating cultured porcine retina.2016Conference paper (Refereed)
  • 143.
    Mohlin, Camilla
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Liljekvist-Soltic, Ingela
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olofsson, Jenny
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Johansson, Kjell
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Neuropathology of cultured retinas: degenerative events and rescue paradigms2011In: Advances in Eye Research. Volume 2 / [ed] William L. Thomsen, Nova Science Publishers, Inc., 2011, no 2, p. 177-190Chapter in book (Refereed)
  • 144.
    Mohlin, Camilla
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Mollik, Tanzina
    Johansson, Kjell
    Human neural progenitor cells are not sufficient to support degenerating photoreceptors in cultured porcine retina.2014Conference paper (Refereed)
  • 145.
    Mohlin, Camilla
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Petrus-Reurer, Sandra
    Karolinska Institutet;Karolinska University Hospital.
    Lanner, Fredrik
    Karolinska Institutet;Karolinska University Hospital.
    Sandholm, Kerstin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Nilsson, Per H.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Univ Oslo, Norway.
    Nilsson, Bo
    Uppsala University.
    Nilsson Ekdahl, Kristina
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala University.
    Is the polarized secretion of complement factor H of importance in age-related macular degeneration?2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal (Other academic)
  • 146.
    Mohlin, Camilla
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Taylor, Linnea
    Univ Lund Hosp.
    Ghosh, Fredrik
    Univ Lund Hosp.
    Johansson, Kjell
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Örebro universitet.
    Autophagy and ER-stress contribute to photoreceptor degeneration in cultured adult porcine retina2014In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1585, p. 167-183Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate rod and cone photoreceptor degeneration in organotypic cultures of adult porcine retina. Our hypothesis was that the photoreceptors accumulate opsins, which, together with exposure to cyclic dim light illumination, induce autophagy and endoplasmic reticulum stress (ER-stress) to overcome damaging protein overload. For this purpose, retinas were cultured for 48 h and 72 h during which they were illuminated with dim light for 8 h/day; specimens were analyzed by means of immunohistochemistry, Western blot, real-time polymerase chain reaction (PCR) and transmission electron microscopy. ER-stress and photoreceptor degeneration was observed in conventionally cultured retinas. The additional stress in the form of dim light illumination for 8 h/day resulted in increased levels of the ER-stress markers GRP78/BiP and CHOP, as well as increased level of active caspase-12. Increased autophagic processes in cone and rod photoreceptors were detected by LC3B-II increases and occurrence of autophagosomes at the ultrastructural level. Illumination also resulted in altered protein expression for autophagy inducers such as p62 and Beclin-1. Moreover, there was a decrease in phosphorylated mammalian target of rapamycin (mTOR), which further indicate an increase of autophagy. Rod and cone photoreceptors in retinas from a diurnal animal that were exposed to dim light illumination in vitro displayed autophagy and ER-stress processes. As no alteration of rhodopsin mRNA was observed, autophagy and ER-stress are suggested to decrease rhodopsin protein at the posttranscriptional level. (C) 2014 Elsevier B.V. All rights reserved.

  • 147.
    Mohlin, Camilla
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Taylor, Linnéa
    Lunds universitet.
    Ghosh, Fredrik
    Lunds universitet.
    Johansson, Kjell
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Autophagy en ER-stress contribute to photoreceptor degenenration in cultured adult porcine retinaManuscript (preprint) (Other academic)
  • 148.
    Mollick, Tanzina
    et al.
    Örebro University.
    Mohlin, Camilla
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Johansson, Kjell
    Örebro University.
    Human neural progenitor cells decrease photoreceptor degeneration, normalize opsin distribution and support synapse structure in cultured porcine retina2016In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1646, p. 522-534Article in journal (Refereed)
    Abstract [en]

    Retinal neurodegenerative disorders like retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy and retinal detachment decrease retinal functionality leading to visual impairment. The pathological events are characterized by photoreceptor degeneration, synaptic disassembly, remodeling of postsynaptic neurons and activation of glial cells. Despite intense research, no effective treatment has been found for these disorders. The current study explores the potential of human neural progenitor cell (hNPC) derived factors to slow the degenerative processes in adult porcine retinal explants. Retinas were cultured for 3 days with or without hNPCs as a feeder layer and investigated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), immunohistochemical, western blot and quantitative real time-polymerase chain reaction (qRT-PCR) techniques. TUNEL showed that hNPCs had the capacity to limit photoreceptor cell death. Among cone photoreceptors, hNPC coculture resulted in better maintenance of cone outer segments and reduced opsin mislocalization. Additionally, maintained synaptic structural integrity and preservation of second order calbindin positive horizontal cells was also observed. However, Müller cell gliosis only seemed to be alleviated in terms of reduced Müller cell density. Our observations indicate that at 3 days of coculture, hNPC derived factors had the capacity to protect photoreceptors, maintain synaptic integrity and support horizontal cell survival. Human neural progenitor cell applied treatment modalities may be an effective strategy to help maintain retinal functionality in neurodegenerative pathologies. Whether hNPCs can independently hinder Müller cell gliosis by utilizing higher concentrations or by combination with other pharmacological agents still needs to be determined.

  • 149.
    Moreno, Laura Hernandez
    et al.
    Univ Minho, Portugal.
    Perdomo, Natacha Moreno
    Hosp Santa Maria Maior EPE, Portugal.
    Lima Ramos, Pedro
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portuga.
    Lewis, Peter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Linhares, Joao
    Univ Minho, Portugal.
    Senra, Hugo
    Anglia Ruskin, UK.
    Santana, Rui
    Univ Nova Lisboa, Portugal.
    Macedo, António Filipe
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Univ Minho, Portugal.
    Visual and psychological outcomes in patients with and without low vision diagnosed with similar eye diseases - initial results.2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal (Other academic)
  • 150.
    Muller, Matthew S.
    et al.
    Aeon Imaging, USA.
    Elsner, Ann E.
    Aeon Imaging, USA;Indiana University, USA.
    Baskaran, Karthikeyan
    Indiana University, USA.
    Kollbaum, Elli J.
    Indiana University, USA.
    Petrig, Benno L.
    Aeon Imaging, USA.
    Real-Time Retinal Imaging with Integrated Visual Function Testing Using the Digital Light Ophthalmoscope2014In: IOVS, Orlando, Florida, USA, 2014, Vol. 55(13)Conference paper (Refereed)
    Abstract [en]

    Abstract Purpose: To perform low cost fixation stability assessment and kinetic perimetry during live fundus viewing using the Digital Light Ophthalmoscope (DLO). Methods: Kinetic perimetry was performed on 12 undilated normal subjects aged 25 - 63 with real-time confocal retinal imaging using the DLO. Having similar functionality to a Scanning Laser Ophthalmoscope, but at far lower cost, the DLO uses a single digital light projector to provide both the illumination for confocal imaging, and the stimuli for visual function measurements. Confocal retinal imaging is performed at 20 Hz with a 35.1 deg field of view. The imaging illumination is provided by a red 630 nm LED, with 40 µW time-averaged power at the cornea. Stimuli are shown in black over the red imaging illumination and are operator controlled in shape and position in real-time. The black stimuli are easily seen by the subject and are also clearly visible on the live view of the fundus. Subjects were instructed to stare at a fixation target while a Goldman V size (1.72 deg diameter) target was presented near the optic nerve head. The path taken by the stimulus was guided by one of eight meridians that converged at a point on the optic nerve head. The meridians were equally separated by 45 deg, and 7 deg long. Each stimulus moved incrementally outwards, from “not seen” to “seen”, at approximately 2.5 deg per sec. Once the stimulus was seen by the subject, an 8 image frame buffer was saved. Fixation stability was separately measured by acquiring 60 frames over 3 sec while the subject fixated on a cross-hair target with 0.3 deg line thickness. Results: The stimuli were directly visible on the retinal image frames, providing precise visual function testing. The visual function maps, formed by registering and superimposing the fundus images obtained for each stimulus meridian path, agreed well with the boundaries of the optic nerve head. The subjects’ fixation was 0.25±0.13 deg, measured over a 2 sec blink-free interval of the 3 sec acquisition. Conclusions: The DLO with integrated visual function testing is a flexible and cost-effective platform for conducting image-corrected visual function tests, such as kinetic perimetry and fixation stability assessment, and can be readily extended to scotoma mapping and reading tests.

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