Adaptation to progressive addition lens-induced optical blur reduces peripheral blur sensitivity

Progressive addition lenses (PALs) introduce spatially varying blur, including blur associated with unwanted astigmatism, but the perceptual consequences of this blur remain poorly understood. We tested whether short-term PAL wear was associated with spatially localized changes in blur sensitivity corresponding to regions of unwanted optical blur or with changes that were more broadly distributed across the visual field. Seven myopic presbyopes with astigmatism and no prior PAL experience were tested before and after two weeks of PAL wear. Blur sensitivity was measured using a two-alternative forced-choice comparison task at randomized visual-field locations, including the fovea, and 7.5 \\(^\\circ\\) and 25 \\(^\\circ\\) eccentricities across eight meridians. Threshold-versus-reference functions measured across five reference blur levels were fitted to estimate intrinsic blur. Linear mixed-effects models showed that two weeks of PAL wear significantly increased blur thresholds and intrinsic blur, indicating reduced blur sensitivity. However, these adaptation-related changes depended on eccentricity, with significant increases observed at 25 \\(^\\circ\\) eccentricity ( p < 0.001), and not at 7.5 \\(^\\circ\\) eccentricity or the fovea. Among the seven participants who completed both assessments, short-term PAL wear was therefore associated with increased blur thresholds and intrinsic blur at 25 \\(^\\circ\\) eccentricity. The absence of statistically detectable meridional dependence suggests that this peripheral change was broadly distributed across the tested locations rather than confined to a specific meridian.