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P. Yao, B.-C. Jiang, R. Chu; The Effect of Blur Adaptation on Objective Depth-of-Focus and Accommodative Response in Different Refractive Groups. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3046.
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To investigate whether blur adaptation has impact on the objective depth-of-focus (DOF) and whether this effect differs in different refractive error groups.
Twelve emmetropes (EMM), 12 stable myopes (SM) and 12 progressing myopes (PM) participated in the study. The refractive errors were corrected using contact lenses. The subjects were instructed to watch a movie at a distance of 4 meters for 30 minutes. A +2.0D lens was imposed on the trial frame to provide blurry image. Visual acuity, accommodative stimulus response curve and objective DOF were measured before and immediately after blur vision task. Visual acuity through +2.0D lens was measured using an ETDRS vision chart. Accommodative response (AR) was measured using a Badal stimulator and infrared autorefractor WAM5500. Objective DOF was determined by the least dioptric vergence that could cause a statistically detectable change in AR at 1D and 4D accommodative stimulus (AS) levels. In a control experiment, the subject repeated above procedure with his normal distant correction.
All subjects exhibited blur adaptation with a mean improvement in visual acuity of -0.16 logMAR. At 4D AS level, objective DOF decreased in SMs (0.082±0.020D vs. 0.064±0.015D, pre- vs. post-adaptation, p<0.05) and increased in PMs (0.093±0.019D vs. 0.144±0.036D, p<0.01). No significant difference in DOF was found in EMMs (0.096±0.024D vs. 0.082±0.025D, p>0.05). At 1D AS level, only PMs showed increased DOF (0.060±0.016D vs. 0.079±0.023D, p<0.01). The DOF in other groups didn’t show significant change after blur adaptation (p>0.05). Compared with pre-adaptation value, no constant difference in AR was found after blur adaptation (p>0.05). Control tests showed no significant change in objective DOF and AR (p>0.05) in all groups after watching a movie for 30 minutes.
Blur adaptation alters the blur sensitivity of the accommodative system in different directions in SMs versus in PMs. The increase of DOF in PMs observed in this study suggests that the PMs are more susceptible to blur image than other refractive error groups.
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