Presbyopia onset affects dynamic visual acuity via motor adaptation in naturalistic viewing conditions

This study investigated how age affects dynamic visual acuity (DVA) and its visuomotor correlates during a high-acuity real-world visual task, focusing on the roles of motor coordination and binocular mechanisms around the onset of presbyopia. Sixty-three participants, ranging from young and adult non-presbyopes to presbyopia-onset individuals and older presbyopes, performed a smartphone-based DVA test while sitting, standing, and walking. The participants’ visuomotor profile was assessed by 8 vergence and accommodation metrics along with 8 motor variables related to smartphone positioning relative to the head. Findings revealed a significant age-related decline in DVA, with the sharpest drop occurring at presbyopia onset. This decline was closely linked to reduced visual accommodation, while vergence had minimal influence. Motor variables, particularly smartphone distance and its antero-posterior and lateral movements, showed a stronger overall impact on DVA. The results suggest that diminished motor adaptation and age-related accommodative changes jointly contribute to the deterioration of DVA during presbyopia onset.