Scanning Laser Polarimetry Using Variable Corneal Compensation in Detection of Localized Visual Field Defects

ABSTRACT

PURPOSE: To evaluate the ability of scanning laser polarimetry parameters and a novel deviation-map algorithm to discriminate between healthy and early glaucomatous eyes with localized visual field defects confined in one hemifield. METHODS: In this prospective case-controlled study, 61 glaucomatous eyes with localized visual field defects and 66 normal controls were enrolled. Humphrey field analyzer 24-2 glaucoma hemifield test and scanning laser polarimetry (GDx-VCC ) were used. RESULTS: There were significant differences in the mean parametric values of TSNIT average, superior average, inferior average, and TSNIT SD (P<0.05) between the glaucoma group and normal subjects. The sensitivity of each GDx-VCC variable was as follows TSNIT average, 47.5%; superior average, 31.1%; inferior average, 47.5%; and TSNIT SD, 24.6% (when abnormal was defined as P<0.05). The overall sensitivities combining each probability scale and severity score at 80%, 90%, and 95% specificity were 90.2%, 72.1%, and 59%, respectively. There was a statistically significant correlation between the GDx-VCC severity score and the visual field severity score (P<0.05). CONCLUSIONS: GDx-VCC parameters may not be sufficiently sensitive to detect glaucomatous patients with localized visual field damage. Our algorithm using the GDx-VCC deviation map may enhance the understanding of GDx-VCC in terms of the locality, deviation size, and severity of localized RNFL defects in eyes with localized visual field loss.