Effects of Refractive Errors and Age on Binocular Function in Normal Adult Population

Abstract Purpose: To investigate the relationship between binocular function with gender, ages, and spherical equivalent (SE) .Methods: This observational study enrolled 243 healthy, non-strabismic adults, including 94 men and 149 women aged from 20 to 59 years. The subjects were divided into three groups according to SE: myopic group, emmetropic group and hyperopic group. The subjects were also divided into four groups according to age: 20-29 years group, 30-39 years group, 40-49 years group, and 50-59 years group. The binocular vision function was measured with a synoptophore, including subjective angle (SA), divergence, convergence and fusional vergence range (FVR). Results: The mean values of SA, divergence, convergence and range of fusion for the whole sample group were 3.33±0.16°, 9.72±0.26°, 19.34±0.54°, and 29.06±0.62°, respectively. The mean values of SA and divergence in myopic group were significantly larger than the emmetropic group (both p<0.05). SE, SA, divergence and FVR were significantly different among age groups (all p<0.05). Besides, linear regression analysis showed SE was correlated with SA and divergence (p=0.007, p=0.003). Age was correlated with SE, SA, divergence and FVR (p<0.001, p<0.001, p=0.005, p=0.002, respectively). In addition, the proportion of SA being in comfort zone (defined as the value of SA located in the middle 1/3 area of FVR) in age groups were statistically different. (χ2=8.283, p=0.041)Conclusion: Both SA and motor fusion are associated with age and SE in normal adult population.