Asymmetry Analysis of the Retinal Nerve Fiber Layer Thickness in Normal Eyes using Optical Coherence Tomography

Purpose: To investigate the asymmetry of the retinal nerve fiber layer thickness (RNFLT) with respect to the horizontal and vertical meridian and between the right and left eye in normal subjects. Methods: The RNFLT was measured in 121 normal volunteers by optical coherence tomography (OCT). The RNFLT was analyzed by dividing the circle scanning area (diameter 3.4 mm) around the optic disc into 4 quadrants and 12 sectors. Results: There was a significant difference between the RNFLT of the nasal and temporal quadrant in individual eyes. There was a significant difference between the RNFLT of corresponding sectors with respect to the vertical or horizontal meridian in individual eyes. The nasal and temporal RNFLTs were asymmetrical between the right and left eye in the quadrant and sector analysis. The RNFLT of the nasal and temporal quadrant was thicker in the right eye. The nasal and inferior RNFLT measured by OCT had a significant correlation with degree of refractive error. Conclusions: In normal subjects without significant anisometropia, there was significant asymmetry of the RNFLT for each eye as well as between the right and left eye. Korean Journal of Ophthalmology 19(4):281-287, 2005