Relation between blue-on-yellow perimetry and optical coherence tomography in normal tension glaucoma

To assess the relation between blue-on-yellow perimetry (B/YP) indices and optical coherence tomography (OCT) parameters in normal tension glaucoma (NTG) patients and to investigate the diagnostic ability of B/YP and OCT in discriminating NTG from normal eyes.

Cross-sectional study.

Eighty normal subjects (80 eyes) and 80 NTG patients (80 eyes) were enrolled in the study.

All patients underwent white-on-white perimetry, B/YP, and OCT measurement. The correlation between B/YP indices and OCT parameters was analyzed. The area of the receiver operating characteristic (ROC) curve was calculated to discriminate NTG patients from normal subjects.

A highly significant correlation was found between B/YP mean deviation (MD) and average thickness of the retinal nerve fibre layer (r2 = 0.707, p = 0.000), and a moderately significant correlation was found between B/YP MD and temporal average (r2 = 0.437, p = 0.010) in the early NTG patients. A mildly or moderately significant correlation was found between B/YP MD and average thickness, inferior average, temporal average, superior maximum, and maximum-minimum (r2 = 0.212-0.498, p = 0.001-0.048) in the moderate or late NTG patients. The area under the ROC curve at the B/YP MD was 0.896, and the 3 OCT parameters with the widest area under the curve were average thickness (0.957), inferior average (0.932), and superior average (0.913). Average thickness showed the highest sensitivity (93%) with specificities at 90% and 80%.

The significant correlation between B/YP indices and OCT parameters in NTG patients suggests that the 2 tests detect similar areas or amounts of NTG damage and could be used for NTG early diagnosis.