Evaluation of photoreceptors in amblyopic eyes using swept-source optical coherence tomography
Background: While the foci responsible for amblyopia are thought to be in the cerebral cortex, it remains controversial whether the retina of amblyopic patients is completely normal. The present study measured foveal bulge (FB) using optical coherence tomography (OCT) and the longitudinal reflectivity profiles (LRP) method with ImageJ in patients with unilateral amblyopia in order to examine the effect of amblyopia on photoreceptor cell normality. Methods: This study enrolled 48 patients (6.8 ± 2.3 years old) with unilateral amblyopia and 29 healthy control children (7.6 ± 3.0 years old) with no history of ocular disease. Macular 3D scan images were obtained using the DRI OCT-1 Atlantis (TOPCON). The FB vertex and foveal pit (FP) positions were then identified using analysis software to evaluate the positional relationship. In addition, FB height was quantified using the LRP method. Results: The logarithm of the minimum angle of resolution (logMAR) was significantly higher in amblyopic eyes as compared to fellow or control eyes (p < 0.001). The FB position was deviated nasally relative to the FP in 14.6 % of the amblyopic eyes, in 0.4 % of the fellow eyes, and in 3.6 % of the control eyes, with others located on the FP. The mean deviation of the FB from the FP was 3.0 ± 7.1 μm in the amblyopic eyes, 2.2 ± 6.4 μm in the fellow eyes, and 0.8 μm in the control eyes. FB heights in the horizontal and vertical sections were 85.4 ± 7.9 μm and 87.5 ± 8.5 μm in the amblyopic eye, respectively, with these values not significantly different from those determined for the fellow or control eyes. Multiple regression analysis was used to evaluate the independent variables of age, logMAR, refractive error, axial length, and central retinal thickness with respect to the dependent variables of the FB height, which showed no significant association between the variables. Conclusions: There was no significant difference between the amblyopic eyes and the fellow or control eyes for the FB position and height, which is considered to reflect the normality of photoreceptors. Our results suggest that amblyopia does not affect the normality of photoreceptors.
