Symmetry of Retinal Parameters Measured by Spectral-domain OCT in Normal Young Adults

To determine interocular differences in retinal parameters in a population of young adults using spectral-domain optical coherence tomography.In the Sydney Adolescent Vascular Eye Study, young adults aged 16 to 19 years received a standardized eye examination encompassing retinal photography, spectral-domain optical coherence tomography (Cirrus HD-OCT; Carl Zeiss Meditec, Dublin, CA) and best-corrected visual acuity. Interocular differences in retinal nerve fiber layer (RNFL) and macular parameters together with sex and ethnic variations for these differences were determined.In the 1500 subjects tested, right eyes had thicker average RNFL than left eyes (0.3 μm, P=0.0074). There were no significant interocular differences in central macular or macular cube average thickness. After adjusting for interocular difference in axial length, right eyes had slightly smaller total macular volume than left eyes (-0.0082 mm, P=0.008). The 2.5% to 97.5% limits of asymmetry were 9.3 μm for average RNFL, 8 μm for average macular thickness, and 0.20 mm for total macular volume. In the outer inferior quadrant, there was a greater macular thickness asymmetry in females than males (-0.7 μm, P=0.037). In the inferior RNFL quadrant (-2.6 μm, P=0.0013) and in the outer inferior macular quadrant (1.6 μm, P=0.0018), white individuals had greater symmetry than East Asians.In this study, we report the degree of interocular symmetry of RNFL and macular parameters measured by Cirrus HD-OCT in healthy young adults.