Quantitative Analysis of Localized Retinal Nerve Fiber Layer Defects Using Spectral Domain Optical Coherence Tomography

Abstract

Purpose:To compare the topographic features of localized retinal nerve fiber layer (RNFL) defects presented in red-free RNFL photography and spectral domain optical coherence tomography (SD-OCT), and to evaluate the correlation with structural and functional parameters.Methods:Sixty eyes with localized RNFL defects in red-free RNFL photographs were included. RNFL thickness map and significance map were obtained by SD-OCT. The angular location, angular width, and area of localized RNFL defects were measured and compared among RNFL thickness map, significance map (red, <1% level; yellow, <5% level), and RNFL photograph. The RNFL defect areas were analyzed by their correlations with structural and functional parameters.Results:The RNFL defect area of RNFL thickness map was significantly greater than those of red significance map, and smaller than those of RNFL photograph and yellow significance map (all P<0.001). RNFL thickness map showed a significantly narrower angular width than RNFL photograph and yellow significance map (all P<0.001). The area, angular width, and angular location of localized RNFL defects in RNFL photographs strongly correlated with those of RNFL thickness maps and significance maps (all r0.741, P<0.001). The relationship between RNFL defect area and structural-functional parameters was also significant.Conclusions:The high topographic correlations in RNFL defects between RNFL photography and SD-OCT RNFL maps suggest the validity of SD-OCT RNFL imaging for detecting localized glaucomatous RNFL damage. In addition, structural and functional parameters are closely related to RNFL defect areas. Quantitative measurements of RNFL defects might be valuable for glaucoma diagnosis.