Development of Topographic Scoring System for Identifying Glaucoma in Myopic Eyes: A Spectral-Domain OCT Study

Abstract

To develop a new scoring system that uses topographic diagnostic signs of spectral-domain (SD) OCT to enhance glaucoma diagnostic performance for myopic eyes and to validate the system's diagnostic ability. Cross-sectional study. A total of 517 patients (517 eyes; spherical equivalent [SE] <-1.0 diopters [D] or axial length >24.0 mm), including 175 highly myopic eyes (SE <-6.0 D or axial length >26.0 mm), were recruited and divided into 2, training (241 eyes) and validation (276 eyes) test sets. Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) topographic signs were selected based on the morphologic patterns of RNFL (size, shape, location, and agreement between deviation and thickness maps) and GCIPL (size, shape, location, color tone, agreement between maps, and step sign) abnormalities indicative of higher likelihood of myopic glaucoma on deviation and thickness maps. The diagnostic score was compiled according to the sensitivity, specificity, and positive likelihood ratio (PLR) of each diagnostic sign using the training set. The area under the receiver operating characteristic curve (AUC) was plotted and compared between the OCT-provided parameters and the scoring system in the validation set. The diagnostic performance of a new scoring system as validated by AUC. Among all of the RNFL and GCIPL parameters, the presence of temporal hemifield asymmetry on the GCIPL thickness map (PLR, 5.98) showed the highest diagnostic ability, followed by location of the RNFL defect (PLR, 5.79) and color tone of the GCIPL defect (PLR, 5.04). The AUC of the topographic scoring system in myopic eyes was 0.979, which was significantly higher than those of the inferior (0.895; P < 0.001) and average (0.894; P < 0.001) RNFL thickness parameters. For highly myopic eyes, the scoring system (AUC, 0.983) also showed a higher diagnostic performance than that of the RNFL and GCIPL thickness parameters (all P < 0.001). Our scoring system including OCT topographic parameters demonstrated to be beneficial for clinicians to differentiate real glaucomatous damage from myopic healthy eyes. Our results support the value of using multitopographic OCT parameters for detecting glaucoma in myopic eyes.