Interocular symmetry in retinal and optic nerve parameters in children as measured by spectral domain optical coherence tomography

Background/aims To report interocular differences in retinal nerve fibre layer (RNFL), optic nerve head and macular parameters in children using spectral domain optical coherence tomography (SD-OCT). Methods This was an observational cross-sectional study including 108 healthy children aged 6-17 years with no ocular abnormality except refractive error. After a comprehensive eye exam and axial length measurement, RNFL, optic nerve and macular thickness measurements were performed using the Cirrus OCT machine. Right and left eyes were compared and interocular differences were computed. Subjects were also divided into two groups based on age (under or over 10 years of age). Main outcome measures were interocular differences and their correlations with age and gender. Results The study included 108 children, mean age 10.7 +/- 3.1 years; significant interocular differences were observed in both macular and RNFL parameters. The macular thickness analysis revealed interocular differences in the outer nasal and outer inferior quadrants, with left eyes displaying larger values. With respect to RNFL parameters, right eyes displayed thicker nasal and temporal quadrants, and inferior clock hours; left eyes had a thicker superior quadrant. The older age group (>10 years) had more pronounced variation in interocular differences compared with the younger group with less mature visual systems. Conclusions Normal variation in interocular symmetry exists. Our results can contribute to establishing a standard reference for interocular differences in OCT parameters in children aged 6-17 years using the Cirrus device.