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Vision evaluation of eccentric refractive correction
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-4894-7944
Vision Enabling Laboratory, School of Optometry, Kalmar University.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0001-9172-858X
2007 (English)In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 84, no 11, 1046-1052 p.Article in journal (Refereed) Published
Abstract [en]

Purpose. This study investigates the benefits of eccentric refractive correction to resolution and detection thresholds in different contrasts for seven subjects with central visual field loss (CFL) and for four healthy control subjects with normal vision.

Methods. Refractive correction in eccentric viewing angles, i.e., the preferred retinal location for the CFL subjects and 20 degrees off-axis for the control subjects, was assessed by photorefraction with the PowerRefractor instrument and by wavefront analysis using the Hartmann-Shack principle. The visual function with both eccentric and central corrections was evaluated using number identification and grating detection.

Results. For the CFL subjects, the resolution and detection thresholds varied between individuals because of different preferred retinal locations and cause of visual field loss. However, all seven CFL subjects showed improved visual function for resolution and detection tasks with eccentric correction compared with central correction. No improvements in high-contrast resolution were found for the control subjects.

Conclusions. These results imply that optical eccentric correction can improve the resolution acuity for subjects with CFL in situations where healthy eyes do not show any improvements.

Place, publisher, year, edition, pages
2007. Vol. 84, no 11, 1046-1052 p.
Keyword [en]
Detection threshold; Eccentric refractive correction; Low vision; Macular degeneration; Periphery; Resolution acuity; Error correction; Error detection; Optical resolving power; Photorefractive materials; Vision; Central visual field loss (CFL); Detection threshold; Eccentric refractive correction; Low vision; Macular degeneration; Optical eccentric correction; Periphery; Photorefraction; Resolution acuity; Refractive index; adult; aged; clinical article; conference paper; control group; controlled study; evaluation; eye refraction; female; human; light refraction; male; optical resolution; priority journal; retina; task performance; vision; visual acuity; visual field; visual field defect; visual impairment; Adult; Diagnostic Techniques, Ophthalmological; Female; Humans; Male; Middle Aged; Refraction, Ocular; Refractometry; Retina; Sensory Thresholds; Vision; Vision Disorders; Visual Acuity; Visual Fields
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-7156DOI: 10.1097/OPX.0b013e318159aa7aISI: 000251040200007PubMedID: 18043424Scopus ID: 2-s2.0-36649005597OAI: oai:DiVA.org:kth-7156DiVA: diva2:12078
Note
QC 20100809. Uppdaterad från Accepted till Published 20100809.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
Opponent
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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