Huanqing Guo1, David A Atchison. 1. School of Optometry and Institute of Health & Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia.
Abstract
PURPOSE: The purpose was to compare subjective blur limits for cylinder and defocus. METHODS: Blur was induced with a deformable, adaptive-optics mirror when either the subjects' own astigmatisms were corrected or when both astigmatisms and higher-order aberrations were corrected. Subjects were cyclopleged and had 5-mm artificial pupils. Black letter targets (0.1, 0.35, and 0.6 logMAR) were presented on white backgrounds. RESULTS: For 10 subjects, blur limits were approximately 50% greater for cylinder than for defocus (in diopters). Although there were considerable effects of axis for individuals, overall, this was not strong, with the 0 degrees (or 180 degrees ) axis having approximately 20% greater limits than oblique axes. In a second experiment with text (equivalent in angle to N10 print at 40 cm distance), cylinder blur limits for six subjects were approximately 30% greater than those for defocus; this percentage was slightly smaller than for the three letters. Blur limits of the text were intermediate between those of 0.35- and 0.6-logMAR letters. Extensive blur limit measurements for one subject with single letters did not show expected interactions between target detail orientation and cylinder axis. CONCLUSIONS: Subjective blur limits for cylinder are 30 to 50% greater than those for defocus, with the overall influence of cylinder axis being 20%.
PURPOSE: The purpose was to compare subjective blur limits for cylinder and defocus. METHODS: Blur was induced with a deformable, adaptive-optics mirror when either the subjects' own astigmatisms were corrected or when both astigmatisms and higher-order aberrations were corrected. Subjects were cyclopleged and had 5-mm artificial pupils. Black letter targets (0.1, 0.35, and 0.6 logMAR) were presented on white backgrounds. RESULTS: For 10 subjects, blur limits were approximately 50% greater for cylinder than for defocus (in diopters). Although there were considerable effects of axis for individuals, overall, this was not strong, with the 0 degrees (or 180 degrees ) axis having approximately 20% greater limits than oblique axes. In a second experiment with text (equivalent in angle to N10 print at 40 cm distance), cylinder blur limits for six subjects were approximately 30% greater than those for defocus; this percentage was slightly smaller than for the three letters. Blur limits of the text were intermediate between those of 0.35- and 0.6-logMAR letters. Extensive blur limit measurements for one subject with single letters did not show expected interactions between target detail orientation and cylinder axis. CONCLUSIONS: Subjective blur limits for cylinder are 30 to 50% greater than those for defocus, with the overall influence of cylinder axis being 20%.
Authors: Susana Marcos; John S Werner; Stephen A Burns; William H Merigan; Pablo Artal; David A Atchison; Karen M Hampson; Richard Legras; Linda Lundstrom; Geungyoung Yoon; Joseph Carroll; Stacey S Choi; Nathan Doble; Adam M Dubis; Alfredo Dubra; Ann Elsner; Ravi Jonnal; Donald T Miller; Michel Paques; Hannah E Smithson; Laura K Young; Yuhua Zhang; Melanie Campbell; Jennifer Hunter; Andrew Metha; Grazyna Palczewska; Jesse Schallek; Lawrence C Sincich Journal: Vision Res Date: 2017-02-27 Impact factor: 1.886
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