Probing glaucoma visual damage by rarebit perimetry

Abstract

Aim: To compare rarebit perimetry (RBP) with standard achromatic perimetry (SAP) in detecting early glaucomatous functional damage.

Methods: 43 patients with ocular hypertension (OH), 39 with early primary open angle glaucoma (POAG), and 41 controls were considered. Visual fields were assessed using the Humphrey field analyser (HFA) 30-2 and RBP tests. Differences among the groups were evaluated using Student-Newman-Keuls and χ² tests. Correlation between HFA and RBP parameters was assessed using the Pearson’s correlation coefficients and regression analysis. Sensitivity and specificity of RBP in detecting early glaucomatous visual damage were calculated with different algorithms.

Results: RBP-mean hit rate (MHR) was respectively 88.6% (SD 4.8%) in controls; 79.1% (10.9%) in the OH group; 64.3% (13.8%) in the POAG group (differences statistically significant). Good correlation in the POAG group was found between HFA-mean deviation and RBP-MHR. Largest AROC (0.95) and optimal sensitivity (97.4%) were obtained when an abnormal RBP test was defined as having (at least 1): MHR <80%; >15 areas with a non-hit rate of >10%; ≥2 areas with a non-hit rate of >50%; at least one area with a non-hit rate of ≥70%.

Conclusions: The RBP appeared to be a rapid, comfortable, and easily available perimetric test (requiring only a PC device), showing a high sensitivity and specificity in detecting early glaucomatous visual field defects.