Original article preliminary exploratory finding of anti-defocus (ADF) contact lenses on binocular vision

Purpose: This study investigated the short-term functional adaptation and impact of three distinct anti-defocus (ADF) contact lens designs on comprehensive binocular visual functions. Methods: This prospective, randomized crossover trial enrolled 35 subjects with clinically significant visual symptoms (CISS ≥ 21; COVD-QOL ≥ 20). Three ADF designs were evaluated: plus-horizontal (PH-ADF), minus-horizontal (MH-ADF), and plus-annular (Ring-ADF). Binocular vision assessments—including visual acuity, accommodative amplitude (AA), accommodative lag (via fused cross cylinder, FCC), relative accommodation (NRA/PRA), contrast sensitivity, phoria, fixation disparity (FD), and accommodative/vergence facility—were conducted at baseline and after 7–10 days of wear. Results: Ring-ADF significantly enhanced near visual acuity and AA while maintaining superior focusing precision (FCC) and fixation stability (FD); however, it induced a more rigid accommodative state by reducing accommodative facility and relative ranges (NRA/PRA). Conversely, both horizontal designs (PH-ADF and MH-ADF) induced a significant increase in accommodative lag. PH-ADF promoted an exophoric shift, whereas MH-ADF elicited a significant esophoric shift and a statistically significant deterioration in stereoacuity, though thresholds remained within the functional range. All designs improved functional field of awareness, with Ring-ADF demonstrating superior high-spatial-frequency contrast sensitivity. Conclusion: Peripheral defocus configuration and polarity are critical determinants of binocular status. While Ring-ADF showed superior accommodative stability, horizontal designs significantly modulated vergence and lag. These findings suggest that ADF geometries can be tailored to specific binocular profiles, though long-term impact requires further investigation.