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Improving Peripheral Vision Through Optical Correction and Stimulus Motion
Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. (Vision Enabling Research Laboratory)ORCID iD: 0000-0002-8365-0601
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 [en]
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: urn:nbn:se:lnu:diva-52286Libris ID: 19440212ISBN: 978-91-88357-14-4 (print)OAI: oai:DiVA.org:lnu-52286DiVA: diva2:924325
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
List of papers
1. Resolution of static and dynamic stimuli in the peripheral visual field.
Open this publication in new window or tab >>Resolution of static and dynamic stimuli in the peripheral visual field.
2011 (English)In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 51, no 16, 1829-1834 p.Article in journal (Refereed) Published
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.

Keyword
DVA; Dynamic visual acuity; Periphery
National Category
Ophthalmology
Research subject
Natural Science, Optometry
Identifiers
urn:nbn:se:lnu:diva-13814 (URN)10.1016/j.visres.2011.06.011 (DOI)21722661 (PubMedID)2-s2.0-79961028317 (Scopus ID)
Available from: 2011-08-18 Created: 2011-08-18 Last updated: 2017-12-08Bibliographically approved
2. Objectively Determined Refraction Improves Peripheral Vision
Open this publication in new window or tab >>Objectively Determined Refraction Improves Peripheral Vision
Show others...
2014 (English)In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 91, no 7, 740-746 p.Article in journal (Refereed) Published
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.

Keyword
visual acuity, low-contrast resolution acuity, off-axis refractive errors, peripheral vision, off-axis astigmatism, macular degeneration, AMD
National Category
Ophthalmology
Research subject
Natural Science, Optometry
Identifiers
urn:nbn:se:lnu:diva-36833 (URN)10.1097/OPX.0000000000000301 (DOI)000338778400010 ()2-s2.0-84903754538 (Scopus ID)
Available from: 2014-09-10 Created: 2014-09-10 Last updated: 2017-12-05Bibliographically approved
3. Benefit of Adaptive Optics Aberration Correction at Preferred Retinal Locus
Open this publication in new window or tab >>Benefit of Adaptive Optics Aberration Correction at Preferred Retinal Locus
Show others...
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

Keyword
REFRACTIVE ERROR, RESOLUTION ACUITY, VISION
National Category
Ophthalmology
Research subject
Natural Science, Optometry
Identifiers
urn:nbn:se:lnu:diva-21527 (URN)10.1097/OPX.0b013e318264f2a7 (DOI)22842306 (PubMedID)2-s2.0-84865730607 (Scopus ID)
Available from: 2012-09-05 Created: 2012-09-05 Last updated: 2017-12-07Bibliographically approved

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