Pilot study of identifying retinal nerve fiber layer defects with optical coherence tomography

Abstract

Background Fundus photography is a traditional method for detecting local retinal nerve fiber layer (RNFL) defects,but the evaluation of its result depends on the observer's experience.The spectral domain optical coherence tomography (OCT) exhibit the defects of RNFL very clearly.Objective This study was to evaluate the diagnosis value and correlation between topographic profiles of localized RNFL defects determined by spectral domain and time domain OCT with fundus photography.Methods Forty-one normal eyes of 41 subjects and 55 eyes of 55 glaucomatous patients with localized,wedge-shaped RNFL defects identified by two glaucoma specialists in fundus photographs were enrolled in the clinical study.The angular location and width of RNFL defects determined on the images of fundus photography,Cirrus HD-OCT and Stratus OCT were analyzed respectively using Pearson's correlation coefficient and linear regression analysis.This study followed the Helsinki declaration and was approved by Ethic Committee of Shenzhen Eye Hospital.Written informed consent was obtained from each individual before the clinical examination.Results Seventy-five RNFL defects were identified in 55 eyes by two glaucoma specialists unanimously with the defect position at superior-temporal and inferior-temporal quadrants.The sensitivity of Cirrus HD-OCT and Stratus OCT to determining RNFL defects were 88.0% and 69.3% respectively and their specificities were 92.7% and 97.6% respectively.The angular locations of RNFL defects by Cirrus HD-OCT and Stratus OCT were highly correlated with those by fundus photography(r=0.993,r=0.992,P＜0.001);while the angular widths of RNFL defects by Cirrus HD-OCT and Stratus OCT were moderately correlated with those by fundus photography(r=0.420,r=0.432,P=0.019,P=0.002).No significant differences were found in the defect width of RNFL between Cirrus HD-OCT or Stratus OCT and fundus photography(Cirrus HD-OCT:P=0.114;Stratus OCT:P=0.074),and significant difference was found in that between Cirrus HD-OCT and Stratus OCT(P=0.002).Conclusion Spectral domain OCT and time domain OCT can localize RNFL defects with high sensitivity and specificity.The measure value of Cirrus HD-OCT and Stratus OCT for RNFL defects shows a good diagnostic agreement with fundus photography. Key words: Optical coherence tomography; Glaucoma; Retinal nerve fiber layer