A Practical Guide for Interpretation of Optical Coherence Tomography Retinal Nerve Fiber Layer Measurement

Structural damage in glaucoma often occurs before detectable loss in visual function.1-3 Accurate assessment of the optic disk and retinal nerve fiber layer (RNFL) morphology, however, is not always an easy task. Optical coherence tomograph (OCT), confocal scanning laser ophthalmoscope (CSLO) and scanning laser polarimeter (SLP) are the 3 commonly used imaging instruments for objective measurement of the optic disk and RNFL in clinical and research settings. While SLP only measures the RNFL and CSLO primarily measures the optic disk, OCT provides cross-sectional imaging for both the RNFL and optic disk. Despite the recent introduction of spectral domain OCT,4 the Stratus OCT is currently the most widely available OCT instrument. Misinterpretation of OCT RNFL analysis is not uncommon among clinicians who have not paid enough attention to the image quality and scan location. This article aims to provide a step-by-step approach for interpretation of Stratus OCT RNFL analysis printout in the evaluation of glaucoma and its progression.