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Assessment of objective and subjective eccentric refraction
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-4894-7944
Rehabilitation Engineering Research, Department of Design Science, Lund University.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0001-9172-858X
2005 (English)In: Optometry and Vision Science, ISSN 1040-5488, E-ISSN 1538-9235, Vol. 82, no 4, 298-306 p.Article in journal (Refereed) Published
Abstract [en]

Purpose. When performing perimetry, refracting subjects with central visual field loss, and in emmetropization studies, it is important to accurately measure peripheral refractive errors. Traditional methods for foveal refraction often give uncertain results in eccentric angles as a result of the large aberrations and the reduced retinal function. The aim of this study is therefore to compare and evaluate four methods for eccentric refraction. Methods. Four eccentric methods were tested on 50 healthy subjects: one novel subjective procedure, optimizing the detection contrast sensitivity with different trial lenses, and three objective ones: photorefraction with a PowerRefractor, wavefront measurements with a Hartmann-Shack sensor, and retinoscopy. The peripheral refractive error in the horizontal nasal visual field of the right eye was measured in 20 degrees and 30 degrees. Results. In general, the eccentric refraction methods compared reasonably well. However, the following differences were noted. Retinoscopy showed a significant difference from the other methods in the axis of astigmatism. In 300 eccentric angle, it was not possible to measure 15 of the subjects with the PowerRefractor and the instrument also tended to underestimate high myopia (<-6 D). The Hartmann-Shack sensor showed a myopic shift of approximately 0.5 D in both eccentricities. The subjective method had a relatively larger spread. Conclusions. This study indicates that it is possible to assess the eccentric refraction with all methods. However, the Hartmann-Shack technique was found to be the most useful method. The agreement between the objective methods and the subjective eccentric refraction shows that detection contrast sensitivity in the periphery is affected by relatively small amounts of defocus.

Place, publisher, year, edition, pages
2005. Vol. 82, no 4, 298-306 p.
Keyword [en]
Contrast sensitivity; Detection; Eccentric refraction; Peripheral vision; Photorefraction; Refractive errors; Retinoscopy; Wavefront aberrations; Aberrations; Diseases; Error analysis; Image sensors; Light refraction; Optical instrument lenses; Sensitivity analysis; Wavefronts; Eccentric angles; Eccentric refraction; Refractive errors; Visual fields; Vision; adult; article; astigmatism; clinical article; contrast sensitivity; eye refraction; female; high myopia; human; light refraction; male; optical instrumentation; priority journal; refraction error; retinoscopy; sensor; visual field; Adult; Aged; Contrast Sensitivity; Corneal Topography; Diagnostic Techniques, Ophthalmological; Female; Fovea Centralis; Humans; Male; Middle Aged; Reference Values; Refraction, Ocular; Retinoscopy; Visual Fields
National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:kth:diva-7154DOI: 10.1097/01.OPX.0000159366.61943.62ISI: 000228572400012PubMedID: 15829857ScopusID: 2-s2.0-17444369423OAI: diva2:12076
QC 20100809Available from: 2007-05-20 Created: 2007-05-20 Last updated: 2012-03-21Bibliographically 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.
Trita-FYS, ISSN 0280-316X ; 2007:34
Optics, Human eye, Aberrations, Peripheral vision, Central visual field loss
National Category
Atom and Molecular Physics and Optics
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
QC 20100809Available from: 2007-05-20 Created: 2007-05-20 Last updated: 2010-08-09Bibliographically approved

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