Subjective blur limits for cylinder
Purpose: To compare subjective blur limits for cylinder and defocus. ----------
Method: 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 ten subjects, blur limits were approximately 50% greater for cylinder than for defocus (in diopters). While there were considerable effects of axis for individuals, overall this was not strong, with the 0° (or 180°) axis having about 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 6 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 logMAR 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. ----------
Conclusion: Subjective blur limits for cylinder are 30%-50% greater than those for defocus, with the overall influence of cylinder axis being 20%.
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|Item Type:||Journal Article|
|Keywords:||Aberration, Adaptive Optics, Astigmatism, Blur limits, Cylinder, Defocus|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Vision Science (111303)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health|
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Optometry & Vision Science
|Copyright Owner:||Copyright 2010 American Academy of Optometry|
|Deposited On:||10 Nov 2010 08:11|
|Last Modified:||01 Mar 2012 00:18|
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