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 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.