Topographic profiles of retinal nerve fiber layer defects affect the diagnostic performance of macular scans in preperimetric glaucoma

To evaluate the influence of topographic profiles (i.e., inner directional angle and angular width) of localized retinal nerve fiber layer (RNFL) defects on the diagnostic performance of macular ganglion cell-inner plexiform layer (GCIPL) thickness in discriminating preperimetric glaucoma (PPG) eyes from normal control eyes. The ganglion cell analysis algorithm in Cirrus OCT was performed to determine the macular GCIPL thickness. Areas under the receiver operating characteristic curves (AUROCs) and the sensitivities/specificities based on an internal normative database were evaluated. The effect of the inner directional angle and the angular width of localized RNFL defects on the diagnostic performance of macular GCIPL parameters were evaluated by using linear-by-linear association analysis and logistic regression analysis. Ninety-two patients with PPG and 92 age-matched healthy control subjects were enrolled in this study. The AUROC of the best parameters in macular GCIPL was 0.823 (inferotemporal sector), which showed no significant difference in comparison to the best parameters of peripapillary RNFL (7 o'clock sector, 0.764) and optic nerve head (rim area, 0.767) (for all comparisons, P > 0.05). A significant linear association was observed between the inner directional angle of RNFL defects and the sensitivity of macular GCIPL parameters for detecting RNFL defects. The angular width of RNFL defects was not significantly associated with the sensitivity of macular GCIPL parameters. The diagnostic ability of macular GCIPL parameters was comparable to that of peripapillary RNFL and ONH parameters in PPG. The inner directional angle of RNFL defects, but not the angular width, affects the diagnostic sensitivity of macular GCIPL parameters.