Impact of type 1 diabetes on binocular vision: Evidence from a comparative analysis

Binocular vision function was assessed in individuals with type 1 diabetes (T1D) without retinopathy and compared to a control group to identify potential nonstrabismic binocular vision disorders. This cross-sectional study included 80 participants (40 T1D, 40 controls) without systemic or ocular diseases, visual impairments, medications, or prior ocular surgery. Highly repeatable tests evaluated heterophoria, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), fusional vergences, vergence facility, and stereoacuity. Diagnosed dysfunctions included convergence insufficiency, divergence insufficiency, basic exophoria, basic esophoria, fusional vergence dysfunction, convergence excess, and divergence excess. Individuals with T1D showed significantly farther NPC (break: 5.50 vs. 3.80 cm, p = 0.005; recovery: 8.32 vs. 5.69 cm, p < 0.001), lower near positive fusional vergence (break: 20.70 Δ vs. 24.25 Δ; recovery: 11.50 Δ vs. 14.75 Δ, p = 0.02 and 0.01, respectively), reduced vergence facility (5.10 vs. 7.15 cpm, p = 0.003), and a lower AC/A ratio (3.30 vs. 4.00, p = 0.01). More participants with T1D had binocular vision parameters outside the normal range, with a higher prevalence of binocular vision disorders (p = 0.048). These findings highlight the impact of T1D on binocular vision and emphasize the need for optometric evaluations for early detection and management.