Abstract
Abstract: :
Purpose:Previous work has demonstrated that many individuals are able to adapt to the presence of a sustained, blurred retinal image, resulting in substantial, significant improvements in visual resolution. However, little information is currently available regarding the decay of this adaptive phenomenon. Furthermore, it is unclear whether brief intervening periods of clear vision following the adaptation will attenuate these improvements in vision. Methods:Two experiments will be described. In the first, the decay of blur adaptation was studied in 10 subjects, all of whom had between 1.50 and 3.00D of myopia. Adaptation was induced by subjects viewing a distant target while uncorrected for a sustained 3-hour period. After the inducing period, subjects left the laboratory wearing their habitual refractive correction. Uncorrected visual acuity was measured periodically during the 48 hours immediately following adaptation. A second study examined the impact of intervening periods of clear vision during blur adaptation in 12 subjects. Here, following 1 hour of adaptation, successive periods of clear vision lasting 1, 5 and 10min, respectively, were allowed, each of which was separated by a further 10min of blur. Results:For the first experiment, immediately following the 3-hour adapting period, mean visual acuity improved from 0.70 to 0.49 logMAR, (p=0.009). Only minimal decay was observed over the subsequent 2-day period, and the mean visual acuity 48 hours post-adaptation was 0.54 logMAR, which was significantly better than the baseline value (p=0.008). In the second experiment, one hour of continuous blur produced a significant improvement in mean visual acuity from 0.90 to 0.64 logMAR (p=0.007). Only minimal change in mean visual resolution (less than 0.01 logMAR) was observed during the subsequent periods of clear vision (p=0.93). Conclusions: These findings demonstrate that the significant and large improvements in visual resolution produced by blur adaptation are robust, extend for at least 48 hours following the adapting period, and are not attenuated by brief intervening periods of clear vision. Accordingly, blur adaptation may reduce the necessity for full-time refractive correction in some individuals.
Keywords: visual acuity • refraction • myopia