An Evaluation of a New 24-2 Metric for Detecting Early Central Glaucomatous Damage

We sought to test the hypothesis that a recently proposed pattern standard deviation (PSD) metric, based upon the 24-2 visual field (VF) test, as well as the PSD of the 10-2 VF, will miss central glaucomatous damage confirmed with an objective structure-function method.

Cross-sectional study.

A glaucoma (G) group (70 eyes/patients) diagnosed with glaucoma and a 24-2 mean deviation better than -6 dB and a healthy (H) group (45 eyes/patients) had 24-2 and 10-2 VFs and optical coherence tomography (OCT) scans twice within 4 weeks. The PSD(C24-2), based upon the central 12 points of the 24-2, was compared with the PSD(10-2). To evaluate central damage (CD) in G eyes with normal PSD(C24-2) values, a post hoc analysis was combined with a CD reference standard (CD-RS), which was based upon an objective, topographic comparison between abnormal points on the 10-2 VF and OCT probability maps.

The 115 PSD(C24-2) and PSD(10-2) values were significantly correlated (Spearman correclation coefficient: rho = 0.55; P < .001) and the number of G eyes (19) identified as abnormal by the PSD(C24-2) was not significantly different from the number (22) identified by the PSD(10-2) (P = .15). However, based upon the CD-RS, 44 of 70 G eyes were classified as abnormal. The PSD(C24-2) missed 27 (61%) of these 44 eyes, and the PSD(10-2) missed 23 (52%) of these eyes. Post hoc analysis revealed clear CD in most of these eyes.

Neither the PSD(C24-2) nor the PSD(10-2) metric is good measure of early CD. Instead we recommend a topographic approach based upon OCT probability maps and a 10-2 VF.