Optometry Research Today is a free monthly online journal that collates and summarizes the latest research about Optometry, including details on myopia, optometric practice, therapy.

Effect of blur adaptation on blur sensitivity and discrimination in emmetropes and myopes.

Cufflin MP, Mankowska A, Mallen EA

Department of Optometry, University of Bradford, Bradford, United Kingdom.

PURPOSE: To determine whether blur adaptation influences blur sensitivity and blur discrimination thresholds in young adult myopes and emmetropes. In addition, to determine whether there is a differential effect of blur adaptation on blur sensitivity and discrimination between refractive error groups. METHODS: Proximal and distal blur sensitivity thresholds and blur discrimination thresholds were measured under cycloplegia with a Badal optometer in 24 young adult subjects (8 emmetropes [EMM], 8 early-onset myopes [EOM], and 8 late-onset myopes [LOM]). Adaptation to 1 D of myopic refractive blur was then undertaken for 30 minutes. Blur sensitivity and discrimination thresholds were then remeasured. RESULTS: After blur adaptation, blur sensitivity, and blur discrimination thresholds were found to be elevated. Blur adaptation had a significant effect on distal blur sensitivity threshold, with the largest effect being observed in the EOMs. Mean changes in distal blur sensitivity thresholds were EMMs +0.03 +/- 0.14 D, EOMs +0.30 +/- 0.21 D, and LOMs +0.08 +/- 0.13 D. CONCLUSIONS: Adaptation to a degraded stimulus modifies the blur detection mechanisms of the visual system in young adults. Depth of focus is expanded by prolonged exposure to defocus. EOMs are more susceptible to this phenomenon than are LOMs and EMMs.

Published 25 May 2007 in Invest Ophthalmol Vis Sci, 48(6): 2932-9.
Full-text of this article is available online (may require subscription).

© 2005-2008 Optometry Research Today. All Rights Reserved.