Diagnostic accuracy of the optical coherence tomography in assessing glaucoma among Filipinos. Part 1: Categorical outcomes­ based on a normative database

Objective@#To determine the accuracy of the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters using the Stratus OCT in diagnosing glaucoma among Filipino patients and to determine the validity of the OCT measurements compared with a reference standard. @*Methods@#Glaucoma suspects were recruited consecutively from patients undergoing diagnostic tests. The results of the Stratus OCT fast RNFL protocol were analyzed against the independent assessment by glaucoma experts who were blinded. Outcomes included RNFL thickness values of ≤5 percentile and ≤1 percentile of the normative database for each RNFL sector, quadrant, and for the average RNFL thickness. Estimates of diagnostic accuracy with 95% confidence intervals were calculated.@*Results@#A total of 119 subjects assessed as glaucoma and 397 subjects assessed as normal were included in the analysis. Using the best categorical criterion for abnormality (average RNFL thickness of ≤1 percentile of the normative database), the OCT had a specificity of 98% (95% CI 96 - 99) and a sensitivity of 37% (95% CI 28 - 46). The criterion with the highest sensitivity was the presence of at least one sector with thickness at ≤5 percentile. @*Conclusion@#The Stratus OCT demonstrated a specificity of 98% and a sensitivity of 37% for the diagnosis of glaucoma using as a criterion an average RNFL thickness of ≤1 percentile of the normative database. It was a poor screening test for glaucoma suspects, although it showed some promise as a confirmatory test.

Correlation Between Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry in Glaucoma Suspects and Glaucomatous Eyes

The aim of this study was to determine the relationship between the frequency doubling technology (FDT) screening algorithm and parapapillary retinal nerve fiber layer (RNFL) thickness in the eyes of glaucoma suspects and patients with open angle glaucoma. FDT C20-1 screening program and a scanning laser polarimetry (SLP) system (GDx-NFA) was used to assess 53 glaucomatous eyes, 53 glaucoma suspects and 36 normal control eyes. In glaucomatous eyes, there were correlations between the FDT the screening algorithm and RNFL retardation values in several polarimetric indices, most significantly "inferior thickness" (r = -0.321, P = 0.029). In the eyes of glaucoma suspects, however, we observed no correlation between the FDT results and RNFL retardation values (r = 0.080, P > 0.05, "inferior thickness"). In glaucomatous eyes, the abnormal scores obtained with FDT screening program correlated negatively with RNFL retardation values, as measured by SLP. Despite poor correlation between the FDT abnormal score and RNFL retardation value in glaucoma suspects, detection of abnormality using the FDT screening protocol may aid in the assessment of early glaucomatous structural damage.