Blue multifocal pupillographic objective perimetry in glaucoma

PURPOSE. This study investigated multifocal pupillographic objective perimetry (mfPOP) stimuli that target the intrinsic photosensitivity of melanopsin retinal ganglion cells. The diagnostic potential for glaucoma is compared between stimuli biased toward either cone input to these cells or their melanopsin response. METHODS. Nineteen glaucoma patients and 24 normal subjects were tested using mfPOP stimulus protocols with either 33-ms yellow or 750-ms blue stimuli. Subjects’ color discrimination was assessed using the Farnsworth 100-hue test. Pupillary responses were measured, and mixed-effects regression was used to quantify results. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) analysis. RESULTS. The mean reduction in moderate to severe glaucoma pupil responses using blue mfPOP stimuli was larger but more variable than that of the shorter yellow stimuli (blue: –1.32 dB [t(40) ¼ –2.29; P ¼ 0.027]; yellow: –0.93 dB [t(40) ¼ –3.13; P ¼ 0.003]). Color discrimination decreased significantly with age and glaucoma, with type III blue-yellow anomalies dominating. ROC analysis revealed similar diagnostic accuracies (AUC for eyes classified as moderate to severe; blue: 81.7%, yellow: 83.7). Slightly higher sensitivity and specificity were obtained using blue stimuli in mild disease (AUCs blue: 71.1, cf. yellow: 67.7), although this difference was not significant. CONCLUSIONS. In moderate to severe glaucoma, diagnostic accuracy of yellow and blue was similar, but blue stimuli showed limited ability to resolve scotomas. Blue mfPOP stimuli, however, may have advantages over yellow in detecting early glaucoma.