Factors Influencing Optic Disc and Retinal Nerve Fiber Layer Parameters Measured by Optical Coherence Tomography

Purpose: To determine the factors influence retinal nerve fiber layer (RNFL) and optic nerve head (ONH) parameters measured by Stratus optical coherence tomography (OCT). Methods: Topographic RNFL thickness and optic disc parameters of 129 healthy Korean subjects of aged 14 to 87 were measured using the fast retinal nerve fiber layer thickness and fast optic disk algorithms of Stratus OCT. One eye of each subject was randomly selected for statistical analysis. Using multiple linear regression, the effect of optic disc area, age, refractive error, and zone beta on each parameter was analyzed. Results: Large discs had large horizontal integrated rim width (HIRW), cup area, rim area, C/D area ratio, and vertical C/D ratio. The thickness of average, superior, inferior, and nasal quadrant RNFL increased significantly with an increase in optic disc area. Average and superior quadrant RNFL thickness, and HIRW decreased with age. Refractive error showed a correlation with the vertical integrated rim area, horizontal C/D ratio, and temporal quadrant RNFL thickness. Gender and zone beta had no statistically significant influence on ONH and RNFL parameters. Conclusions: This study shows that optic disc size affects most RNFL thickness and ONH parameters. Because of the relationships revealed in this study, optic disc area in addition to age should be considered when the Stratus OCT RNFL thickness and ONH parameters are interpreted.