Retinal nerve fiber layer thickness in unilateral amblyopia

PURPOSE: To test the hypothesis that eyes with amblyopia may have thicker retina, retinal nerve fiber layer thickness (RNFLT) was investigated in patients with unilateral amblyopia. METHODS: Thirty-eight patients with unilateral amblyopia were studied. Among them, 20 patients had amblyopia with strabismus and 18 had refractive amblyopia without strabismus. Nineteen of 38 had anisometropia of 2.0 D or more. In addition, 17 patients with anisometropia of 2.0 D or more but without amblyopia were enrolled as control subjects. RNFLT was measured by optical coherence tomography with scan pattern "Nerve Head 2.0R" (Carl Zeiss Meditec, Dublin, CA). Average RNFLT was multiplied with their corresponding scan circumferences to estimate the integral values of the total RNFL area (RNFLT(estimated integrals)). RESULTS: In all 38 patients with unilateral amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopic eyes and the normal fellow eyes were statistically significant. Multivariate regression analysis with adjustment for axial length, spherical equivalence, age, and sex indicated significant differences as well. In the group of strabismic amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopic eyes and the normal fellow eyes did not reach statistical significance. However, in the group of refractive amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopia eyes and the normal fellow eyes both had a statistical significance. In the 19 patients with anisometropic amblyopia, the difference in RNFLT and in RNFLT(estimated integrals) between the amblyopic eyes and the normal fellow eyes were statistically significant. In the control group of 17 patients with nonamblyopic anisometropia, the difference in RNFLT and in RNFLT(estimated integrals) between both eyes did not reach statistical significance. CONCLUSIONS: RNFLT may be affected by refractive amblyopia, but further histopathologic confirmation is needed.