Diagnostic Accuracy of the Optical Coherence Tomography in Assessing Glaucoma Among Filipinos. Part 1: Categorical Outcomes Based on a Normative Database
Noel de Jesus Atienza, MD, MSc and Joseph Anthony Tumbocon, MD
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.
Keywords:Glaucoma, Glaucoma suspects, Optical coherence tomography, Glaucoma imaging