Low contrast visual acuity in healthy adults: Impact on non-pathologic myopia

Increase in myopia is a social issue worldwide. However, whether non-pathologic myopia with normal best-corrected visual acuity (BCVA) exhibits differences in visual ability is not well-documented. Data of 43 healthy eyes in 43 participants (52.8 ± 6.07 years) including 13 (30.2%) males who underwent eye medical checkups at Fujita Medical Innovation Center, Tokyo were retrospectively analyzed. Eyes with general BCVA 0 in logMAR or better and without histories of ocular diseases and surgeries were included. Mean low-contrast visual acuity (LCVA) measured using grey-scale optotypes with best correction was 0.17 ± 0.13 (range, -0.079-0.53; median, 0.15). LCVA was correlated with age (r = 0.2634, 95% confidence interval [CI] -0.040-0.522, P = 0.039). Eyes with LCVA better than 0.15 was associated with uncorrected visual acuity (OR, 43.425; 95%CI, 3.729-1250.027; P = 0.010), subjective spherical equivalent (OR, 1.761; 95%CI, 1.255-2.776; P = 0.004), subjective spherical power (OR, 1.616; 95%CI, 1.186-2.433; P = 0.008), and axial length (OR, 0.550; 95%CI, 0.293-0.951; P = 0.032) after adjusted for age and sex. Mean LCVA of less myopic eyes with spherical equivalent > -3.0 diopters was 0.12 ± 0.10 (median, 0.10), and that of more myopic eyes was 0.23 ± 0.14 (median, 0.22) (P < 0.001). Non-pathological myopic eyes exhibited worse LCVA under best correction and had a risk of worse visual ability.