Comparison of confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography to discriminate ocular hypertension and glaucoma at an early stage

Background: The aim was to compare the ability of confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and optical coherence tomography (OCT) to discriminate eyes with ocular hypertension (OHT), glaucoma-suspect eyes (GS) or early glaucomatous eyes (EG) from normal eyes. Methods: Ocular hypertension, GS, and EG were defined as normal disc with intraocular pressure > 21 mmHg, glaucomatous disc without visual field loss, and glaucomatous disc accompanying the early glaucomatous visual filed loss respectively. Ninety-three normal eyes, 26 OHT, 55 GS, and 67 EG were enrolled. Optic disc configuration was analyzed by CSLO (version 3.04), whereas retinal nerve fiber layer thickness was analyzed by SLP (GDx-VCC; version 5.3.2) and OCT-1 (version A6X1) in each individual. The measurements were compared in the four groups of patients. Receiver operating characteristic curve (ROC) and area under the curve (AUC) discriminating OHT, GS or EG from normal eyes were compared for the three instruments. Results: Most parameters in GS and EG eyes showed significant differences compared with normal eyes. However, there were few significant differences between normal and OHT eyes. No significant differences were observed in AUCs between SLP and OCT. In EG eyes, the greatest AUC parameter in OCT (inferior-120; 0.932) had a higher AUC than that in CSLO (vertical cup/disc ratio; 0.845; P=0.017). In GS, the greatest AUC parameter in OCT (average retinal nerve fiber layer [RNFL] thickness; 0.869; P=0.002) and SLP (nerve fiber indicator [NFI]; 0.875; P=0.002) had higher AUC than that in CSLO (vertical cup/disc ratio; 0.720). Conclusions: Three instruments were useful in identifying GS and EG eyes. For glaucomatous eyes with or without early visual field defects, SLP and OCT performed similarly or had better discriminating abilities compared with CSLO.