Peripheral astigmatism in emmetropic eyes
2001 (English)In: Ophthalmic & physiological optics, ISSN 0275-5408, E-ISSN 1475-1313, Vol. 21, no 5, 393-400 p.Article in journal (Refereed) Published
The long-term aim of the work introduced here is to investigate the influence of off-axis aberrations on human vision, especially for subjects with a large central scotoma. The latter use their peripheral vision in spite of its poor off-axis optical quality, and a correction of the off-axis aberrations might be of great assistance. The eccentric fixation angles used by these subjects can be up to 20-30 degrees. In this initial study we have measured oblique astigmatism, the major off-axis aberration, in 20 emmetropic eyes in 10 degrees steps out to 60 degrees nasally and temporally using a 'double pass' setup. The results show very large individual differences and the oblique astigmatism also varies from nasal to temporal side. In an off-axis measurement angle of 30 degrees the astigmatism varied between subjects from 1 to 7-D, with a mean astigmatism of about 4-D on the nasal side and about 1.5-D lower on the temporal side. At 60 degrees temporally, the mean astigmatism was 7-D. At 60 degrees nasally, all subjects had astigmatism larger than 8-D and the mean astigmatism was 11-D. The results indicate that any attempt to correct the off axis astigmatism in an eye with central scotoma cannot be based on central refraction; instead, individual measurements are necessary.
Place, publisher, year, edition, pages
2001. Vol. 21, no 5, 393-400 p.
double-pass measurements, image quality, model eye, aberrations
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:kth:diva-20926ISI: 000170851000008OAI: oai:DiVA.org:kth-20926DiVA: diva2:339623
QC 20100525 NR 201408042010-08-102010-08-102012-02-14Bibliographically approved