Diagnostic capability of optical coherence tomography (Stratus OCT 3) in early glaucoma

Purpose: To evaluate the diagnostic capability of optical coherence tomography (Stratus OCT 3) for early glaucoma in Asian Indian eyes. Design: Cross-sectional observational study. Participants: Two groups of patients (early glaucoma and normal) who satisfied the inclusion and exclusion criteria were included. Early glaucoma was diagnosed in presence of open angles, characteristic glaucomatous optic disc changes correlating with the visual field on automated perimetry (visual field defect fulfilling at least 2 of Anderson and Patella's 3 criteria with mean deviation >= -6 dB). Normals had visual acuity >= 20/30, intraocular pressure <22 mmHg with normal optic disc and fields and no ocular abnormality. Methods: All patients underwent complete ophthalmic evaluation including visual field examination (24-2/30-2 SITA standard program) and imaging with Stratus OCT 3. Main Outcome Measures: Sensitivity, specificity, positive and negative predictive values, area under the receiving operating characteristic curve and likelihood ratios were calculated for various Stratus OCT 3 parameters. Results: Seventy-two eyes (72 patients) with early glaucoma and 96 eyes (96 normal subjects) were analyzed. The inferior maximum parameter had the best combination of sensitivity and specificity, 75% (95% confidence interval [Cl], 70.2-79.8%) and 89.6% (95% Cl, 82.6-96.6%), respectively. The 6-o'clock parameter had a sensitivity of 61.1% (95% Cl, 52.3-69.9) and specificity of 99% (95% Cl, 95-100); for an assumed prevalence of 5%, the positive and negative predictive values were 75% and 98%, respectively. The positive likelihood ratio for the 6-o'clock parameter (P<5%) in early glaucoma was 61. Conclusions: Optical coherence tomography has moderate sensitivity with high specificity for the diagnosis of early glaucoma and may have a potential role in screening.