Blue-on-yellow perimetry and optical coherence tomography in patients with preperimetric glaucoma

Purpose: To investigate the diagnostic ability of blue-on-yellow perimetry (B/YP) and Stratus optical coherence tomography (OCT) in discriminating preperimetric glaucoma from normal eyes. Methods: A total 40 eyes of 40 normal subjects, 38 eyes of 38 preperimetric glaucoma patients (normal standard automated perimetry [SAP] and retinal nerve fibre layer [RNFL] defects or localized optic disc notching and thinning) were enrolled in the study. All the patients underwent SAP and B/YP tests, and OCT measurements. The correlation between B/YP indices and OCT parameters in the eyes with preperimetric glaucoma was analysed. Receiver operating characteristic (ROC) curve area was calculated to discriminate preperimetric glaucoma from normal eyes. Results: In preperimetric glaucoma, 42% eyes (16/38) had B/YP visual field loss, and 68% eyes (26/38) had RNFL defects with OCT measurements. A mild significant correlation was found between B/YP pattern standard deviation (PSD) and average RNFL thickness (Avg.Thi) (R2 = 0.112, P = 0.012), superior maximum (Smax) (R2 = 0.140, P = 0.005) and maximum-minimum (Max-Min) (R2 = 0.074, P = 0.042) in the preperimetric glaucoma group. The areas under the ROC curve for B/YP PSD and B/YP mean deviation were 0.721 and 0.665, respectively, and the three OCT parameters with the widest areas under the ROC curve were Avg.Thi (0.719), inferior average (Iavg) (0.718) and nasal average (Navg) (0.706). The highest sensitivity of the individual B/YP indices and OCT parameters for detection of preperimetric glaucoma was B/YP mean deviation (32%) and Smax/Navg (40%) at 90% specificity; the highest sensitivity of the individual B/YP indices and OCT parameters was B/YP PSD (49%) and Iavg (56%) at 80% specificity. Conclusion: The sensitivity of B/YP indices and Stratus OCT RNFL thickness parameters is low for detecting preperimetric glaucoma, suggesting that BYP and OCT as utilized in this study have limited utility in the detection of preperimetric glaucoma.