Risk factors for amblyopia in congenital anterior lens opacities

We sought to identify the features of congenital anterior lens opacities (CALOs), which are associated with increased risk for amblyopia.

We undertook a retrospective study of 59 patients with CALO from 3 clinical practices. The following variables were examined: type (polar, subcapsular, or pyramidal), location (central, paracentral, or peripheral), diameter, presence of adherent iris tissue, anisometropia (spherical equivalent), unilateral versus bilateral, and presence or absence of amblyopia. Pearson chi-square and independent sample t-tests were conducted to evaluate if any of the aforementioned variables were independently associated with amblyopia. Relative risk was then calculated for significantly related variables (P < 0.05).

Amblyopia was present in 17 of 59 patients (28.8%). Patients with amblyopia had a mean anisometropia of 1.23 diopters whereas nonambyopic patients had a mean anisometropia of 0.25 (P = 0.023). The relative risk for amblyopia with anisometropia of one diopter or greater was 6.5 (95% confidence interval = 3.79-7.45). The mean cataract size in the amblyopic eyes was 1.22 mm (range, 0.7-2.0 mm). Mean cataract size in the nonamblyopic eyes was 0.95 mm (range, 0.5-2.0 mm). This difference in mean cataract size was significant with independent sample t-tests (P = 0.02); however, this difference did not remain significant with logistic regression. Cataract size was not a significant relative risk factor for amblyopia.

Our overall incidence of amblyopia was 28.8%. The only variable associated with increased relative risk for amblyopia in this group of patients was anisometropia. Patients with CALO who have anisometropia of 1 diopter or greater are 6.5 times more likely to develop amblyopia.