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  • 1.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Lewis, Peter
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosen, 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.
    Effects of Optical Defocus on Resolution Acuity in Preferred Retinal Locus2011In: Invest Ophthalmol Vis Sci 2011;52: E-Abstract 1900., 2011, Vol. 52, no 6Conference paper (Refereed)
    Abstract [en]

    PurposeResolution acuity in the peripheral visual field is primarily limited by retinal sampling. In healthy eyes, the correction of peripheral refractive errors does not produce significant visual benefits other than improved detection and low contrast acuity. However, studies (Lundstrom L et al, Optom Vis Sci, 2007;84:1046-52) have shown that peripheral refractive corrections improve resolution acuity in subjects with central visual field loss (CFL) who have an established preferred retinal locus (PRL). The aim of this study was to evaluate the effect of optical defocus on high contrast resolution acuity in the PRL. MethodsResolution acuity was evaluated under spherical defocus in the PRL of three low vision subjects (mean age 75 years) with long standing CFL (due to age-related macular degeneration). Off-axis refractive error at the PRL was measured by an open-field COAS-HD VR aberrometer and was corrected accordingly. The PRL for subject 1 was located at 10{degrees} in the temporal visual field (left eye), subject 2 at 20{degrees} in the nasal visual field (right eye) and subject 3 at 15{degrees} in the inferior visual field (left eye). Stimuli consisting of high-contrast Gabor patches with a visible diameter of 3{o} were presented on a CRT monitor situated 1.0 meter from the subject. Resolution thresholds for static visual acuity (SVA) and dynamic visual acuity (DVA) were obtained using an adaptive Bayesian algorithm. Fixation was aided using illuminated concentric rings covering {+/-}25{degrees} in the visual field. Defocus was altered in 1D steps up to {+/-}4D. When measuring DVA, the sine-wave gratings drifted within the Gaussian envelope at an angular velocity of 1{degrees}/sec. ResultsResolution thresholds for both SVA and DVA in the PRL varied significantly with the amount of optical defocus. The results show a 2 - 3 line decrease (logMAR) in SVA and DVA with 4 D positive and negative defocus. There was no significant difference between SVA and DVA with increasing defocus. In the absence of defocus, SVA was significantly better than DVA in the PRL. ConclusionsDefocus as low as one dioptre has an impact on both static and dynamic high contrast resolution acuity for CFL subjects using a PRL. The results of this study suggest that, for CFL subjects using a PRL, resolution acuity is not only sampling limited but also influenced by the optics of the eye.

  • 2.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosen, R.
    Lewis, Peter
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Unsbo, P.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Benefit of Adaptive Optics Aberration Correction at Preferred Retinal Locus2012In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 89, no 9, p. 1417-1423Article in journal (Refereed)
    Abstract [en]

    PURPOSE.: To investigate the effect of eccentric refractive correction and full aberration correction on both high- and low-contrast grating resolution at the preferred retinal locus (PRL) of a single low-vision subject with a long-standing central scotoma. METHODS.: The subject was a 68-year-old women with bilateral absolute central scotoma due to Stargardt disease. She developed a single PRL located 25 degrees nasally of the damaged macula in her left eye, this being the better of the two eyes. High- (100%) and low-contrast (25 and 10%) grating resolution acuity was evaluated using four different correction conditions. The first two corrections were solely refractive error corrections, namely, habitual spectacle correction and full spherocylindrical correction. The latter two corrections were two versions of adaptive optics corrections of all aberrations, namely, habitual spectacle correction with aberration correction and full spherocylindrical refractive correction with aberration correction. RESULTS.: The mean high-contrast (100%) resolution acuity with her habitual correction was 1.06 logMAR, which improved to 1.00 logMAR with full spherocylindrical correction. Under the same conditions, low-contrast (25%) acuity improved from 1.30 to 1.14 logMAR. With adaptive optics aberration correction, the high-contrast resolution acuities improved to 0.89/0.92 logMAR and the low-contrast acuities improved to 1.04/1.06 logMAR under both correction modalities. The low-contrast (10%) resolution acuity was 1.34 logMAR with adaptive optics aberration correction; however, with purely refractive error corrections, she was unable to identify the orientation of the gratings. CONCLUSIONS.: Correction of all aberrations using adaptive optics improves both high- and low-contrast resolution acuity at the PRL of a single low-vision subject with long-standing absolute central scotoma

  • 3.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    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.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Influence of age on peripheral aberration2010Conference paper (Refereed)
    Abstract [en]

    The purpose of this study is to compare peripheral higher order aberrations in young

    and old emmetropic eyes across the horizontal (±40°) and inferior (–20°) visual field.

    Introduction

     

     

    People with central visual field loss use eccentric fixation for various visual tasks.

    Recently studies have shown that the correction of lower order aberrations (defocus &

    astigmatism) can improve eccentric vision in subjects with central visual field loss

    (CFL)[1]. The CFL subjects mostly correspond to older age groups who use eccentric

    fixation angles up to 20°–30°. While there have been studies comparing the off-axis

    lower order aberrations in normal young and old subjects[2], there is only one recent

    study, which has compared off-axis higher order aberrations in normal young and old

    emmetropic eyes up to 20° (horizontal and vertical) eccentricity[3]. In this study we

    have measured off-axis aberrations in a group of 10 young (23 ± 3 years) and 10 old

    (57 ± 4 years) emmetropes. The aberrations of the right eye were measured using

    COAS-HD VR Hartmann-Shack aberrometer in steps 10° out to ± 40° horizontally and

    –20° inferiorly in the visual field. Subjects rotated the eyes to view the fixation targets,

    which were red light emitting diodes, placed at 3 meter from the eye. The aberrations

    were quantified for a pupil area 5 mm in diameter.

    Discussion

     

     

    Mixed between-within subject’s analysis of variance of the horizontal coma C13

    showed that there was a statistically significant difference between age groups

    (p<0.05). The coma increased linearly in both groups from nasal to temporal visual

    field. The rate of change was greater in the old (slope = –0.027 μm/deg) compared

    to the young (slope = –0.012 μm/deg) emmetropes. In the inferior visual field,

    vertical coma C-13 changed linearly in both groups with higher values in old (slope =

    0.015 μm/deg) compared to young (slope = 0.006 μm/deg). The mean spherical

    aberration was positive in older emmetropes (0.053 μm) compared to young

    emmetropes (-0.030 μm). The HO RMS showed a quadratic increase in the

    periphery for both age groups. The HO RMS was greater in older emmetropes but it

    was not statistically significant (p>0.05) when compared to young emmetropes.

     

    Conclusions

     

     

    Our results show that there is an increase in coma, spherical aberration, and HO

    RMS with age in the periphery.

  • 4.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    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.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Measurement of Off-axis Refraction with a Commercial Open Field Aberrometer2010Conference paper (Refereed)
    Abstract [en]

    Purpose:

    People with central visual field loss (CFL) use their remaining peripheral vision in order to see better when performing various visual related tasks. At large off-axis angles, the eccentric vision can be limited both by the low resolution capacity of the peripheral retina and by the optical aberrations caused due to oblique angles. Previous work has shown that eccentric correction of induced off-axis astigmatism can improve vision in a preferred retinal location (PRL) for people with CFL. However, the eccentric refraction is often difficult to determine with traditional refractive methods. This work therefore shows the use of a commercially available wavefront sensor to measure fast and reliable off-axis refraction. Data on off-axis refraction is also of interest in the field of myopia research.

    Methods:

    We used the new open-field high-definition complete ophthalmic analysis system, COAS HD -VR, to evaluate off-axis refraction. Using the special Vision Research tool in this system stimulus (fixation objects) can be presented in a large part of the visual field. The instrument can measure out to 40 degrees in the horizontal visual field and 20 degrees in the vertical visual field with a range from sphere +7 D to − 17 D. It measures astigmatism up to 10 D. This instrument also allows natural binocular viewing without obstacles. Aberrations of the right eye of 30 emmetropes (24 ± 4 years) were studied. Off-axis refraction and higher order (HO) aberrations were measured in steps of 10° out to ± 30° in the horizontal visual field

    Results:

    The first data on young emmetropic eyes with this new instrument showed promising results for low (LO) and higher order (HO) aberrations in the peripheral visual field. Of the LO aberrations, astigmatism increased significantly with the off–axis angle, from 0.25 D at 10° Nasal to 1.65 D at 30° Nasal. In the HO aberrations, coma (C13) showed a linear increase across the horizontal visual field (p < 0.05)

    Conclusions:

    The COAS HD-VR shows promising results and good usability for future research in evaluation of off-axis refraction. In future we believe the aberrometer can be used clinically to measure off-axis refractions in low vision patients.

  • 5.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    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.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Ocular Aberrations in the Peripheral Visual Field With a Commercial Open-View Aberrometer2010In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 51, no 5, article id 3951Article in journal (Refereed)
    Abstract [en]

    PurposeThe interest in off-axis aberrations has increased with the discovery of a possible link between myopia development and peripheral optics. The most common technology to measure the off-axis aberrations is a Shack-Hartmann wavefront aberrometer. This is the first study to report peripheral aberrations in a large sample of emmetropic population with a commercial open-view Shack-Hartmann aberrometer. MethodsThe commercial open-view Shack-Hartmann aberrometer COAS-HD VR was used to measure the aberrations in the peripheral vision. Aberrations of the right eye of 30 emmetropes (24 {+/-} 4 years) were studied. Off-axis aberrations were measured in steps of 10{degrees} out to {+/-} 30{degrees} in the horizontal visual field. The subjects turned their eye to view the off-axis fixation target (light emitting diode placed at 3 meters) during the measurement. The resulting wavefront aberrations were parameterized with Zernike coefficients for a 5 mm diameter pupil. All analyzes are reported according to optical society of America (OSA) recommended standards. ResultsAberrations from the 2nd to 6th order and the total higher-order root-mean-square (HO RMS) were analyzed using one-way ANOVA. The defocus C02 was significantly myopic in the nasal visual field (+20{degrees}, +30{degrees}) whereas there was no significant difference in the temporal visual field. Astigmatism C22 increased quadratically from {+/-}10{degrees} in the periphery and coma C13 showed a linear increase across the horizontal visual field (p < 0.05). The spherical aberration C04 and the total HO RMS showed a significant change at {+/-}30o. ConclusionsOur results showed that in young emmetropes there was a significant increase of HO RMS at {+/-}30{degrees}, which is expected. Astigmatism, horizontal coma, and spherical aberration vary systematically across the horizontal visual field in agreement with Seidel theory. The findings of our study with a large sample of emmetropic population agree with the previous studies done with laboratory built aberrometers.

  • 6.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Theagarayan, Baskar
    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.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Repeatability of Peripheral Aberrations in Young Emmetropes2010In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 87, no 10, p. 751-759Article in journal (Refereed)
    Abstract [en]

    PURPOSE.: The purpose of this study is to assess the intrasession repeatability of ocular aberration measurements in the peripheral visual field with a commercially available Shack-Hartmann aberrometer (complete ophthalmic analysis system-high definition-vision research). The higher-order off-axis aberrations data in young healthy emmetropic eyes are also reported.

    METHODS.: The aberrations of the right eye of 18 emmetropes were measured using an aberrometer with an open field of view that allows peripheral measurements. Five repeated measures of ocular aberrations were obtained and assessed in steps of 10 degrees out to +/-40 degrees in the horizontal visual field (nasal + and temporal -) and -20 degrees in the inferior visual field. The coefficient of repeatability, coefficient of variation, and the intraclass correlation coefficient were calculated as a measure of intrasession repeatability.

    RESULTS.: In all eccentric angles, the repeatability of the third- and fourth-order aberrations was better than the fifth and sixth order aberrations. The coefficient of variation was <30% and the intraclass correlation coefficient was >0.90 for the third and fourth order but reduced gradually for higher orders. There was no statistical significant difference in variance of total higher-order root mean square between on- and off-axis measurements (p > 0.05). The aberration data in this group of young emmetropes showed that the horizontal coma (C13) was most positive at 40 degrees in the temporal field, decreasing linearly toward negative values with increasing off-axis angle into the nasal field, whereas all other higher-order aberrations showed little or no change.

    CONCLUSIONS.: The complete ophthalmic analysis system-high definition-vision research provides fast, repeatable, and valid peripheral aberration measurements and can be used efficiently to measure off-axis aberrations in the peripheral visual field

  • 7.
    Baskaran, Karthikeyan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Unsbo, Peter
    Biomedical and X-Ray Physics.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Influence of age on peripheral ocular aberrations.2011In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 88, no 9, p. 1088-1098Article in journal (Refereed)
    Abstract [en]

    PURPOSE.: To compare peripheral lower and higher order aberrations across the horizontal (±40°) and inferior (-20°) visual fields in healthy groups of young and old emmetropes. METHODS.: We have measured off-axis aberrations in the groups of 30 younger (24 ± 3 years) and 30 older (58 ± 5 years) emmetropes. The aberrations of OD were measured using the COAS-HD VR Shack-Hartmann aberrometer in 10° steps to ±40° horizontally and -20° inferiorly in the visual field. The aberrations were quantified with Zernike polynomials for a 4 mm pupil diameter. The second-order aberration coefficients were converted to their respective refraction components (M, J45, and J180). Mixed between-within subjects, analysis of variance were used to determine whether there were significant differences in the refraction and aberration components for the between-subjects variable age and the within-subjects variable eccentricity. RESULTS.: Peripheral refraction components were similar in both age groups. Among the higher order coefficients, horizontal coma (C3) and spherical aberration (C4) varied mostly between the groups. Coma increased linearly with eccentricity, at a more rapid rate in the older group than in the younger group. Spherical aberration was more positive in the older group compared with the younger group. Higher order root mean square increased more rapidly with eccentricity in the older group. CONCLUSIONS.: Like the axial higher order aberrations, the peripheral higher order aberrations of emmetropes increase with age, particularly coma and spherical aberration.

  • 8. Franzen, L.
    et al.
    Unsbo, P.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Increased Dynamic Range of a Hartmann Schak Sensor by B-Spline Extrapolation: Measurement of Large Aberrations in the Human Eye2002Conference paper (Refereed)
  • 9. Gislén, Anna
    et al.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Kröger H.H, Ronald
    The accommodative pupil responses of children and young adults at low and intermediate levels of ambient illumination2008In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 48, no 8, p. 989-993Article in journal (Refereed)
    Abstract [en]

    Accommodative pupil constrictions were compared between 27 children (9-10 years) and 13 young adults (22-26 years) in order to clarify the issue whether or not children have such a response. Accommodative stimuli of 4 and 7 diopters were used to elicit the response and experiments were performed at 5 and 100 lux in order to investigate whether the level of ambient light has different effects on developing and mature visual systems. The accommodative pupil response is present in children, but weaker than in adults. Different levels of ambient light lead to only minor additional differences between children and adults. The weaker accommodative pupil response of children may be a consequence of their superior accommodative ranges, which make it unnecessary to close the pupil to increase depth of field. Adults, in contrast, may do better with smaller pupils that reduce accommodative demand because of increased depth of field. A mature human visual system may furthermore be better tuned to handle dimmer and thus noisier images in the photopic range than the developing visual system of a child. (C) 2008 Elsevier Ltd. All rights reserved.

  • 10. Grube, M.
    et al.
    Hemmingsen, L.
    Inde, K.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The See More Project2005Conference paper (Refereed)
  • 11.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Eccentric correction and Low Vision Enabling2003Conference paper (Other academic)
  • 12.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Eccentric Correction in CFL subjects2002Conference paper (Other academic)
  • 13.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Eccentric Correction of Low Order Aberrations in Absolute Central Visual Field Loss2009Conference paper (Refereed)
  • 14.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Se Mer - ett projekt om att använda synen bättre hos barn med medfödd synskada2005In: Optikeren, Norway, no AprilArticle in journal (Other academic)
  • 15.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The first successful eccentric correction2001In: Visual Impairement Research, Vol. 3, no 3, p. 147-155Article in journal (Refereed)
  • 16.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Vision Enabling2008Conference paper (Other academic)
  • 17.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Visual Evaluation of Eccentric Correction in Subjects with Large Central Vision Field Loss2006Conference paper (Refereed)
  • 18.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    "Widesight"- a Project Aimed at Improving Peripheral Vision2000Conference paper (Refereed)
  • 19.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, K
    Low Vision training – SEE MORE and SEEnior2008Conference paper (Other academic)
  • 20.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    Scandinavian low vision services - Similarities and differences2008Conference paper (Refereed)
  • 21.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The history and current status of low vision services in the Scandinavian countries2009In: Journal of Visual Impairment & Blindness, ISSN 0145-482X, E-ISSN 1559-1476, Vol. 103, no 9, p. 558-562Article in journal (Refereed)
  • 22.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    The MoviText method: Efficient pre-optical reading training in persons with central visual field loss2004In: Technology and Disability, Vol. 6, p. 211-221Article in journal (Refereed)
  • 23.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Mohn Jensen, Gaute
    Tömta, Arne
    Kobberö, Kirsten
    Mejlvang, Jytte
    Baggesen, Kirsten
    Utveckling och nuläge för Skandinavisk synrehabilitering2009In: Optik, ISSN 1653-3666, no 12, p. 41-52Article in journal (Other academic)
    Abstract [sv]

    Syftet med denna studie var att samla inuppgifter om likheter och skillnader i förhållandetill personal, budget för hjälpmedel,och organisationsstrukturen inomsynrehabiliteringen i de tre länderna Sverige,Danmark och Norge.

  • 24.
    Gustafsson, Jörgen
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Inde, Krister
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Mohn Jenssen, Gaute
    Tömta, Arne
    Kobberö, Kirsten
    Mejlvang, Jytte
    Baggesen, Kirsten
    Synrehabiliteringen i Skandinavien2010In: Optikeren, ISSN 0333-1598, E-ISSN 1891-0874, no 1, p. 42-45Article in journal (Other academic)
  • 25.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Mohn Jenssen, Gaute
    Tömta, Arne
    Kobberö, Kirsten
    Mejlvang, Jytte
    Baggesen, Kirsten
    Synrehabiliteringen i Skandinavien – situationen idag2009In: Oftalmolog (København), ISSN 0108-5344, no September, p. 25-27Article in journal (Other academic)
  • 26.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Inde, Krister
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Theagarayan, Baskar
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Low Vision Services System in Scandinavia2009Conference paper (Refereed)
  • 27.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Johansson, Anna-karin
    Kalm, Maja
    Evaluation of Low visual Acuity with Berkeley Rudimentary Vision Test2009Conference paper (Refereed)
  • 28.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Jönsson, B.
    Möller, B.
    Petterson, B.
    Raytracing in the Peripheral Optics of the Eye2000In: Abstract Publication, ISBN 91-7170-589-9, Uppsala, Sweden, 2000Conference paper (Refereed)
  • 29.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lundström, L.
    Unsbo, P.
    Eccentric Correction improves the visual function in Subjects with Large Central Visual Field Loss,2005Conference paper (Refereed)
  • 30.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lundström, L.
    Unsbo, P.
    Eccentric Correction in Subjects with Central Visual Field Loss,2005Conference paper (Refereed)
  • 31.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lundström, L.
    Unsbo, P.
    Visual Evaluation of Resolution Acuity With Eccentric Refractive Correction2007Conference paper (Refereed)
  • 32.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Terenius, Erik
    Buchheister, Jan
    Unsbo, Peter
    Peripheral Astigmatism in Emmetropic Eyes2001In: Opthhalm. Physiol. Opt., Vol. 21, no 5, p. 393-400Article in journal (Refereed)
  • 33.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unsbo, P.
    Correcting peripheral Refractive Errors in Low Vision2001Conference paper (Refereed)
  • 34.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unsbo, P.
    Eccentric Correction in Low Vision Subjects with Central Visual Field Loss2002Conference paper (Refereed)
  • 35.
    Gustafsson, Jörgen
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unsbo, Peter
    Eccentric correction for off-axis vision in central visual field loss2003In: Optometry & Vision Science, Vol. 80, no 7, p. 535-541Article in journal (Refereed)
  • 36. Inde, K.
    et al.
    Grube, M.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hemmingsen, L.
    Visual desire and efficiency through Peakabooks and PC Games for low vision children2005Conference paper (Refereed)
  • 37. Inde, K.
    et al.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    MoviText – an efficient pre-optical training for eccentric readers2005Conference paper (Refereed)
  • 38. Inde, Krister
    et al.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    SEEnior – a New Scandinavian Vision Enabling Project for AMD Participants2008Conference paper (Refereed)
  • 39.
    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.

  • 40.
    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.

  • 41.
    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)
  • 42.
    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
    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.
    The Effect of Refractive-Correction on Peripheral Low-Contrast Resolution Acuity2012Conference paper (Other academic)
    Abstract [en]

    Purpose: High-contrast resolution acuity in the peripheral retina has been shown to be sampling-limited, however, a recent study indicates that peripheral low-contrast resolution acuity (PLCRA) is degraded by imposition of optical defocus. On the other hand, it has not been investigated whether refractive errors present in the peripheral field of normal, emmetropic eyes are sufficient to degrade PLCRA. The aim of this study was to evaluate the effect of peripheral refractive-correction on PLCRA in young emmetropes.Methods: Low-contrast (10 %) resolution acuity was measured off-axis (20° nasal visual field) on the right eyes of 10 emmetropic subjects (age 22 ± 2 years), both with and without peripheral refractive correction. Central and peripheral refractive errors were acquired using an open-field COAS-HD VR aberrometer. Stimuli, consisting of low-contrast Gabor patches with a visible diameter of 2°, were presented on a CRT monitor situated 3.0 meters from the subjects. Resolution thresholds were determined using a 2-alternative forced-choice Bayesian algorithm.Results: All the subjects had off-axis astigmatism (against-the-rule) at 20° in the nasal visual field ranging from -1.00 DC to -2.00 DC; of which four had -1.00 DC, three had -1.25 DC, one had -1.50 DC and the remaining two had -2.00 DC. Two of the subjects with -1.25 DC had -0.50 DS to -0.75 DS spherical errors; the rest had purely cylindrical errors. The mean uncorrected and corrected low-contrast resolution acuities for all subjects were 0.92 logMAR and 0.86 logMAR respectively. This shows an improvement in resolution acuity of 0.06 logMAR (p = 0.028) after correction of off-axis refractive errors. However when grouped according to the amount of astigmatism, the -1.00 DC group showed no difference in acuity with correction, the -1.25 DC, -1.50 DC and -2.00 DC groups improved on average by 0.05, 0.14 and 0.16 logMAR respectively.Conclusions: Correction of off-axis refractive errors had a positive effect on low-contrast resolution thresholds in the peripheral visual field on the emmetropic subjects in this study. Moreover, the effects become appreciable only for those subjects having larger degrees of astigmatism. This suggests that optical factors influence peripheral visual tasks involving low-contrast. There may be benefits in correcting even moderate amounts of off-axis refractive errors, especially for people who rely on optimal peripheral visual function.

  • 43.
    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.

  • 44.
    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.

  • 45.
    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.

  • 46.
    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.

  • 47. Lundström, L.
    et al.
    Gorceix, N.
    Manzanera, S.
    Prietro, P.M.
    Ayala, D.B.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unsbo, P.
    Artal, P.
    Effect of Aberration Correction on Visual Acuity in the Periphery2007Conference paper (Refereed)
  • 48. Lundström, L.
    et al.
    Manzanera, Silvestre
    Prito, Pedro M.
    Ayala, Diego B.
    Gorceix, Nicolas
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unsbo, Peter
    Artal, Pablo
    Effect of optical correction and remaining aberrations on peripheral resolution acuity in the human eye2007In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, no 20, p. 12654-12661Article in journal (Refereed)
  • 49. Lundström, L.
    et al.
    Rosén, R.
    Baskaran, Karthikeyan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Jaeken, B.
    Gustafsson, Jörgen
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Artal, P.
    Unsbo, P.
    Symmetries in peripheral ocular aberrations2011In: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 58, no 19-20 SI, p. 1690-1695Article in journal (Refereed)
    Abstract [en]

    A mirror symmetry in the aberrations between the left and right eyes has previously been found foveally, but while a similar symmetry for the peripheral visual field is likely, it has not been investigated. Nevertheless, the peripheral optical quality is often evaluated in only one eye, because it is more time efficient than analyzing the whole visual field of both eyes. This study investigates the correctness of such an approach by measuring the peripheral wavefront aberrations in both eyes of 22 subjects out to +/- 40 degrees horizontally. The largest aberrations (defocus, astigmatism, and coma) were found to be significantly correlated between the left and right eyes when comparing the same temporal or nasal angle. The slope of the regression line was close to +/- 1 (within 0.05) for these aberrations, with a negative slope for the horizontally odd aberrations, i.e. the left and right eyes are mirror symmetric. These findings justify that the average result, sampled in one of the two eyes of many subjects, can be generalized to the other eye as well.

  • 50. Lundström, L.
    et al.
    Unsbo, P.
    Gustafsson, Jörgen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Assessment of objective - subjective eccentric refraction2004Conference paper (Refereed)
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