Purpose: To measure and compare distance and near visual acuity in amblyopic patients.
Methods: This study was evaluated 167 patients with amblyopia between ages of 6 and 55 years. In all subjects, a comprehensive ophthalmic examination including visual acuity, refraction, slit lamp biomicroscopy, and funduscopy was performed. Distance visual acuity (DVA) was measured by Snellen chart at 4 m and near visual acuity (NVA) was measured by Snellen chart at 40 cm, and then DVA and NVA were compered and analyzed.
In our subjects, the mean distance and near visual acuity was 0.39± 0.30 log MAR and 0.30± 0.32 log MAR respectively. The mean NVA was 0.12±0.12 log MAR better than DVA and difference between them was statistically significant (P<0.001). In 40% of patients, there were no difference between DVA and NVA, and in 60% of them, NVA was 0.1 or more log MAR better than DVA. The difference between DVA and NVA was not significantly related with age (p=0.225), spherical equivalent (P=.820) and strabismus (P=.336) and type of amblyopia (P=.405). Although all of these subjects had subnormal DVA, but 43 subjects (26%) had normal NVA. In mild and moderate amblyopic groups, difference between DVA and NVA was 0.14±0.10 log MAR and 0.15±0.14 log MAR respectively, but in severe amblyopic group it was 0.03±0.08 log MAR. The difference between DVA and NVA showed a significant relation with severity of amblyopia (P<0.001). The difference between DVA and NVA was 0.16±0.11 log MAR in patients with history of amblyopia therapy and 0.07.± 0.11 log MAR in patients without treatment. This difference was statistically significant (P<0.001).
Conclusion: Our results showed that near visual acuity in amblyopia especially in mild to moderate types was significantly better than distance visual acuity. More than 50% of subjects with mild amblyopia had normal near visual acuity. The difference between DVA and NVA showed no relation with age, spherical equivalent, strabismus, and type of amblyopia. Also, difference between the DVA and NVA in patients with history of amblyopia therapy was better than of it in non-treated subjects.