Retinal Nerve Fiber Layer Volume Measurements in Healthy Subjects Using Spectral Domain Optical Coherence Tomography

Abstract

Purpose: To report retinal nerve fiber layer (RNFL) volume measurement using spectral domain optical coherence tomography (SD-OCT). We determined the characteristics and effecting factors of the RNFL volume in healthy eyes. Methods: Eighty-six eyes from 86 healthy volunteers were included. All participants underwent 3D-disc scanning using SD-OCT. We developed a computer program using Matlab software to extract RNFL thickness values from colored topographic RNFL thickness map. Total average, quadrant, and clock-hour RNFL volume were automatically calculated between 2.5 and 5 mm diameter circles using the length, width, and height of each pixel derived from the RNFL thickness map. Results: The mean total RNFL volume was 1.478 +/- 0.124 mm(3) and RNFL volume profiles showed double-hump patterns. RNFL volumes of superior and inferior quadrants were significantly greater than those of temporal and nasal quadrants (all P < 0.001). A strong correlation existed between RNFL volume and conventional circumpapillary RNFL thickness measured by built-in software (R = 0.895 to 0.972). Image quality and age were associated with RNFL volume measurement. Conclusions: RNFL volume measurement from RNFL thickness map analysis provides an alternative approach to characterizing and evaluating RNFL. RNFL volume measurement may be valuable for the objective and quantitative evaluation of 3-dimensional RFNL changes.