Gonioscopy vs. anterior segment tomography: a comparative study

Abstract

Objective: To correlate the results of gonioscopy (with and without indentation) with the trabecular-iris angle (TIA) obtained with anterior segment optical coherence tomography (AS-OCT), and to identify the cutoff value that best relates to gonioscopic angle closure.
Material and method: Comparative observational study of 180 patients evaluated for suspected angle closure conducted between July and December 2018 in a glaucoma polyclinic. All patients were evaluated by a glaucoma subspecialist using gonioscopy with a 4M-Sussman gonioscopy lens and Zeiss HD 5000 OCT with an additional lens to evaluate the anterior chamber using the TIA parameter in the nasal and temporal quadrants. Data were processed by the same examiner.
Results: Evaluation of iridocorneal angles by gonioscopy and of TIA measurements obtained by AS-OCT in a subgroup of patients with suspected angle closure revealed a statistically significant association (p< 0.05) between both methods in the temporal quadrant, with a cutoff value of 24 and 25 degrees, thus enabling to distinguish a gonioscopically narrow angle (Shaffer ≤ 2) from one that is not (Shaffer >2), but only with moderate sensitivity (83.3%) and low specificity (2.4%).
Conclusions: A statistically significant correlation between gonioscopy and AS-OCT for the detection of angle closure was found; however, sensitivity was moderate and specificity, low. In addition, this correlation was present only in the temporal quadrant, and not in the nasal quadrant, and it had a cutoff value of 24 and 25 degrees (with the same degree of correlation), i.e. greater than detected in other studies.

Key words: gonioscopy, anterior segment optical coherence tomography, glaucoma, angle closure, diagnosis.