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Effect of optical correction and remaining aberrations on peripheral resolution acuity in the human eye
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-4894-7944
Laboratorio de Optica, Universidad de Murcia.
Laboratorio de Optica, Universidad de Murcia.
Laboratorio de Optica, Universidad de Murcia.
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2007 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, no 20, 12654-12661 p.Article in journal (Refereed) Published
Abstract [en]

Retinal sampling poses a fundamental limit to resolution acuity in the periphery. However, reduced image quality from optical aberrations may also influence peripheral resolution. In this study, we investigate the impact of different degrees of optical correction on acuity in the periphery. We used an adaptive optics system to measure and modify the off-axis aberrations of the right eye of six normal subjects at 20 degrees eccentricity. The system consists of a Hartmann-Shack sensor, a deformable mirror, and a channel for visual testing. Four different optical corrections were tested, ranging from foveal sphero-cylindrical correction to full correction of eccentric low- and high-order monochromatic aberrations. High-contrast visual acuity was measured in green light using a forced choice procedure with Landolt C's, viewed via the deformable mirror through a 4.8-mm artificial pupil. The Zernike terms mainly induced by eccentricity were defocus and with- and against-the-rule astigmatism and each correction condition was successfully implemented. On average, resolution decimal visual acuity improved from 0.057 to 0.061 as the total root-mean-square wavefront error changed from 1.01 mu m to 0.05 mu m. However, this small tendency of improvement in visual acuity with correction was not significant. The results suggest that for our experimental conditions and subjects, the resolution acuity in the periphery cannot be improved with optical correction.

Place, publisher, year, edition, pages
2007. Vol. 15, no 20, 12654-12661 p.
Keyword [en]
Aberrations; Mean square error; Optical resolving power; Optical sensors; Wavefronts; Optical correction; Resolution acuity; Resolution decimal visual acuity; Root-mean-square wavefront error; Optical variables control
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-7155DOI: 10.1364/OE.15.012654ISI: 000250006700010Scopus ID: 2-s2.0-35148840052OAI: oai:DiVA.org:kth-7155DiVA: diva2:12077
Note

QC 20100809. Uppdaterad från Submitted till Published 20100809.

QC 20150727

Available from: 2007-05-20 Created: 2007-05-20 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Wavefront Aberrations and Peripheral Vision
Open this publication in new window or tab >>Wavefront Aberrations and Peripheral Vision
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Failing eyesight causes a dramatic change in life. The aim of this project is to help people with large central visual field loss to better utilize their remaining vision. Central visual field loss means that the person has to rely on peripheral vision since the direct vision is lost, often due to a dysfunctional macula. In these cases, a full restoration of vision would require replacement or repair of the damaged retinal tissue, which is not yet possible. Instead, the present study seeks to improve peripheral vision by enhancing the image quality on the remaining functional part of the retina by optical corrections. The off-axis optics of the human eye often suffers from large optical errors, which together with the lower sampling density of the retina explain the limited visual function in the periphery. The dominating aberrations are field curvature and oblique astigmatism, which induce an effective eccentric refractive error. However, the irregular character of the aberrations and the limited neural function in the periphery will make it difficult to find the optimal refractive correction; the conventional subjective refraction, for example, is not suitable for subjects with large central visual field loss. Within the work of this thesis a Hartmann-Shack wavefront sensor has been constructed for oblique aberration measurements. Wavefront sensing is an objective method to assess detailed information about the optical errors in the human eye. Theory and methods have been developed to allow accurate off-axis measurements of the large aberrations, enable eccentric fixation, and handle the elliptical pupil. The study has mainly concentrated on sphero-cylindrical correction of peripheral vision. Peripheral resolution and detection acuity thresholds have been evaluated for seven subjects with central visual field loss and ten control subjects with normal vision. Five of the subjects with field loss showed improved resolution acuity with eccentric refractive correction compared to their habitual central correction, whereas little change was found for the control subjects. These results demonstrate that correction of peripheral optical errors can be beneficial to people with large central visual field loss in situations where a normal healthy eye does not experience any improvements. In conclusion, it is worthwhile to investigate the peripheral refractive errors in low-vision rehabilitation of central visual field loss and prescribe spectacle correction when those errors are large.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. ix, 52 p.
Series
Trita-FYS, ISSN 0280-316X ; 2007:34
Keyword
Optics, Human eye, Aberrations, Peripheral vision, Central visual field loss
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-4385 (URN)978-91-7178-665-4 (ISBN)
Public defence
2007-06-01, FD5, KTH, AlbaNova, Roslagstullsbacken 21, Stockholm, 13:00
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Supervisors
Note
QC 20100809Available from: 2007-05-20 Created: 2007-05-20 Last updated: 2010-08-09Bibliographically approved

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Lundström, LindaUnsbo, Peter

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