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Benefit of Adaptive Optics Aberration Correction at Preferred Retinal Locus
Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. (Vision Enabling Lab)ORCID iD: 0000-0002-3745-0035
Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. (Vision Enabling Lab)ORCID iD: 0000-0002-8365-0601
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2012 (English)In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 89, no 9, 1417-1423 p.Article in journal (Refereed) Published
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

Place, publisher, year, edition, pages
2012. Vol. 89, no 9, 1417-1423 p.
Keyword [en]
REFRACTIVE ERROR, RESOLUTION ACUITY, VISION
National Category
Ophthalmology
Research subject
Natural Science, Optometry
Identifiers
URN: urn:nbn:se:lnu:diva-21527DOI: 10.1097/OPX.0b013e318264f2a7PubMedID: 22842306Scopus ID: 2-s2.0-84865730607OAI: oai:DiVA.org:lnu-21527DiVA: diva2:549765
Available from: 2012-09-05 Created: 2012-09-05 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Optimal Use of Peripheral Vision
Open this publication in new window or tab >>Optimal Use of Peripheral Vision
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

People who lose their central vision have to rely on their peripheral vision for all visual tasks. The ability to resolve fine details in the periphery is reduced due to retinal limitations and the optical aberrations arising from the use of off-axis vision. The aim of this work is to improve vision by enhancing the image quality at the preferred retinal locus by means of correcting the optical errors. The focus of this thesis has been to measure and correct peripheral optical errors, as well as to evaluate their impact on resolution acuity in both normal and central visual field loss subjects.

 In order to measure peripheral optics we employed a COAS HD VR open view aberrometer which is based on the Hartmann-Shack principle. Psychophysical methods were used to evaluate peripheral grating resolution acuity. We assessed the repeatability of the wavefront sensor in measuring the peripheral ocular aberrations. The symmetry of peripheral ocular aberrations between the left and right eyes was examined. The influence of age on peripheral ocular aberrations was also investigated. We evaluated peripheral vision with sphero-cylindrical correction in healthy eyes and performed the first adaptive optics aberration correction at the preferred retinal locus of a single central visual field loss subject.

 We found that the aberrometer was repeatable and reliable in measuring peripheral ocular aberrations. There was mirror symmetry between the two eyes for most of the peripheral aberration coefficients. Age had a significant influence on peripheral ocular aberrations; there were larger amounts of higher-order aberrations in old eyes than in young eyes. Peripheral low contrast resolution acuity improved with peripheral refractive correction in subjects who had higher amounts of off-axis astigmatism. Finally, adaptive optics aberration correction improved both high and low contrast resolution acuity measured at the preferred retinal locus of the single low vision subject.

 Because of their versatility, open view aberrometers will hopefully be a standard clinical instrument at low vision clinics as they allow for measurements to be rapidly performed at any location in the visual field. The existence of off-axis astigmatism should be better communicated within the low-vision rehabilitation community. Currently, the off-axis refractive errors can be corrected with conventional methods and we hope that the higher-order aberrations can also be corrected in a more realistic ways in the future.  

 In conclusion, this thesis has shown that peripheral visual function can be improved by optical correction. The findings of this thesis have broadened the knowledge of peripheral optical errors and their influence on vision.

Place, publisher, year, edition, pages
Kalmar, Växjö: Linnaeus University Press, 2012
Series
Linnaeus University Dissertations, 108/2012
Keyword
off-axis refractive errors, peripheral aberrations, aberrometers, central visual field loss, preferred retinal locus, eccentric viewing, absolute central scotoma, adaptive optics, eccentric correction.
National Category
Ophthalmology
Research subject
Natural Science, Optometry
Identifiers
urn:nbn:se:lnu:diva-22562 (URN)978-91-86983-94-9 (ISBN)
Public defence
2012-12-20, N2007, Smålandsgatan 26E, Kalmar, 10:00 (English)
Opponent
Supervisors
Available from: 2012-11-23 Created: 2012-11-21 Last updated: 2016-04-27Bibliographically approved
2. Improving Peripheral Vision Through Optical Correction and Stimulus Motion
Open this publication in new window or tab >>Improving Peripheral Vision Through Optical Correction and Stimulus Motion
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The loss of central vision subsequent to macular disease is often extremely debilitating. People with central field loss (CFL) must use other peripheral areas of the retina in order to see; areas with inferior resolution capacity, which are also affected by off-axis optical errors. The overall aim of the work encompassed by this thesis was to identify and evaluate methods of improving vision for people with CFL; with focus on the effects of off-axis optical correction and stimulus motion on resolution acuity and contrast sensitivity.

Off-axis optical errors were measured using a commercially-available COAS-HD VR open-view aberrometer. We used adaptive psychophysical methods to evaluate grating resolution acuity and contrast sensitivity in the peripheral visual field; drifting gratings were employed to   measure the effect of motion on these two measures of visual performance. The effect of sphero-cylindrical correction and stimulus motion on visual performance in healthy eyes and in subjects with CFL was also studied; in addition, the effect of adaptive optics aberration correction was examined in one subject with CFL.

The COAS-HD aberrometer provided rapid and reliable measurements of off-axis refractive errors. Correction of these errors gave improvements in low-contrast resolution acuity in subjects with higher amounts of oblique astigmatism. Optical correction also improved high-contrast resolution acuity in most subjects with CFL, but not for healthy subjects. Adaptive optics correction improved both high and low contrast resolution acuity in the preferred retinal locus of a subject with CFL. The effect of stimulus motion depended on spatial frequency; motion of 7.5 Hz improved contrast sensitivity for stimuli of low spatial frequency in healthy and CFL subjects. Motion of 15 Hz had little effect on contrast sensitivity for low spatial frequency but resulted in reduced contrast sensitivity for higher spatial frequencies in healthy subjects. Finally, high-contrast resolution acuity was relatively insensitive to stimulus motion in the periphery.

This thesis has served to broaden the knowledge regarding peripheral optical errors, stimulus motion and their effects on visual function, both in healthy subjects and in people with CFL. Overall it has shown that correction of off-axis refractive errors is important for optimizing peripheral vision in subjects with CFL; the use of an open-view aberrometer simplifies the determination of these errors. In addition, moderate stimulus motion can have a beneficial effect on contrast sensitivity for objects of predominantly low spatial frequency.

Place, publisher, year, edition, pages
Växjö: Linnaeus University Press, 2016. 172 p.
Series
Linnaeus University Dissertations, 248/2016
Keyword
absolute central scotoma, central visual field loss, eccentric viewing, preferred retinal locus, open-view aberrometer, off-axis refractive errors, eccentric correction, dynamic visual acuity, spatial contrast sensitivity, temporal contrast sensitivity, spatio-temporal contrast sensitivity
National Category
Other Medical Sciences not elsewhere specified
Research subject
Natural Science, Optometry; Natural Science, Biomedical Sciences
Identifiers
urn:nbn:se:lnu:diva-52286 (URN)978-91-88357-14-4 (ISBN)
Public defence
2016-05-19, N2007, Smålandsgatan 26E, Kalmar, 09:45 (English)
Opponent
Supervisors
Available from: 2016-05-13 Created: 2016-04-28 Last updated: 2017-01-27Bibliographically approved

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Baskaran, KarthikeyanLewis, PeterGustafsson, Jörgen

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