Agreement between Pentacam and optical coherence tomography in the assessment of iridocorneal angle width in a large healthy population

Abstract

Purpose: To analyze the agreement between Pentacam and optical coherence tomography (OCT) in the assessment of trabecular-iris angle (TIA) width in a large population of normal subjects.

Methods: A cross-sectional study was performed in 989 right eyes of 989 healthy subjects. The trabecular-iris angle (TIA) was measured in the temporal and nasal quadrants using the Pentacam (Oculus, Wetzlar, Germany), a device based on Scheimpflug technology and RTVue 100 OCT (Optovue, Fremont, CA, USA). Intraclass correlation coefficients (ICC) and Bland-Altman plots were used to evaluate agreement between these devices.

Results: Mean age was 49.1±15.2 years (18-84); 61% were women and spherical error range was -14 to 8.25. TIA could be measured by OCT in 94.9% and 94.1% in the temporal and nasal quadrants, with a mean value of 35.8±13.2 degrees (2.5-78.7) and 35.7±12.9 degrees (2.2-76.8) respectively. TIA was able to be measured by Pentacam in 95.2% and 95% in the temporal and nasal quadrants and means were 35.7±7.3 degrees (11-74.2) and 36.4±8.2 degrees (14.5-64) respectively. An ICC of 0.378 (95% confidence interval [CI], 0.322-0.431) and 0.589 (95% CI 0.546-0.629) for the temporal and nasal quadrants was obtained, showing moderate agreement between the devices. Bland-Altman plots revealed that, compared with OCT, Pentacam tends to overestimate measurements in narrow angles and underestimate these in open angles.

Conclusions: Agreement between OCT and Pentacam was mediocre, indicating the two devices are not interchangeable when used to measure angle width.

Keywords: Angle de la chambre antérieure; Angle irido-cornéen; Anterior segment optical coherence tomography; Anterior-chamber angle; Caméra de Scheimpflug; Glaucoma; Glaucome; Iridocorneal angle; Scheimpflug device; Tomographie en cohérence optique du segment antérieur.