Abstract
Purpose
To quantitatively investigate the reflectivity and structure of the outer retinal layers in children with hyperopic anisometropic amblyopia using swept-source optical coherence tomography (SS-OCT).
Methods
Seventy-eight patients with amblyopia and 64 age-matched children with normal vision were included in this study. All participants underwent SS-OCT and detailed ophthalmic examinations. Longitudinal reflectance profile measurements (LRP) were measured by Image J. The reflectivity of outer retinal layers was measured at the three selected positions: subfovea, 1 mm nasal to the fovea and 1 mm temporal to the fovea. The reflectivity ratios were calculated by outer retinal layers divided by the nuclear layer (ONL) for normalization. Photoreceptor outer segment layer thickness was also measured. The results were compared between the amblyopia and normal controls. The possible effects of age, sex and axial length on results were adjusted by generalized estimating equations (GEE).
Results
Photoreceptor outer segment layer thickness was significantly greater in amblyopic eyes than in normal control eyes at all three regions (18.41 ± 1.83 vs 16.84 ± 1.39, p < 0.001 at fovea; 14.78 ± 1.34 vs 14.19 ± 1.40, p = 0.030 at 1mm nasal to the foveal; 14.92 ± 1.48 vs 14.41 ± 1.32, p = 0.049 at 1mm temporal to the fovea). The reflectivity ratio of outer segment/ONL was higher only at 1mm nasal to the fovea (2.94 ± 0.61 vs 2.70 ± 0.42, p = 0.02). Subfoveal OS thickness was positively correlated with choroidal thickness (r = 0.248, p = 0.018), but was not correlated with spherical equivalent, age, axial length or LogMAR visual acuity.
Conclusions
Quantitative measurement of SS-OCT images revealed that greater photoreceptor outer segment in both eyes of children with amblyopia than in normal control eyes. A thicker OS thickness is somehow related to amblyopia, and this may be a new useful diagnostic parameter for amblyopia.