Reduced photoreceptor outer segment layer thickness in mild commotio retinae without ellipsoid zone disruption

Purpose To quantitatively investigate the reflectivity and structure of the outer retinal layers on spectral-domain optical coherence tomography (SD-OCT) in commotio retinae. Methods Nineteen patients with acute macular commotio retinae and 19 age-matched normal controls were examined using SD-OCT. Longitudinal reflectance profiles (LRP) were obtained using Image J. The reflectivity of outer retinal layers was measured at the fovea, 1 mm nasal to fovea and 1 mm temporal to fovea. The reflectivity ratios of outer retinal layers divided by the outer nuclear layer (ONL) were calculated for normalization. Photoreceptor outer segment layer thickness was also measured. The results were compared between the patients and controls. Results The reflectivity ratio of ellipsoid zone/ONL and outer segment/ONL was higher in commotio retinae than in controls only at fovea (12.66 +/- 4.73 vs 9.67 +/- 3.34, p = 0.041; 7.70 +/- 2.20 vs 3.73 +/- 1.63, p < 0.001, respectively) but not at 1 mm nasal or temporal to the fovea. Photoreceptor outer segment layer thickness was significantly shorter in commotio retinae compared to controls at all three locations (19.64 +/- 3.05 vs 25.16 +/- 3.53, 16.95 +/- 4.02 vs 20.00 +/- 3.00, and 15.42 +/- 3.22 vs 20.05 +/- 2.48, respectively, all p < 0.05). Conclusions Quantitative measurement of SD-OCT images revealed that shortening of photoreceptor outer segment is an additional, and potentially better, biomarker for commotio retinae on top of increased reflectivity.