Characterizing Anterior Segment OCT Angle Landmarks of the Trabecular Meshwork Complex

Area of Science:

• Ophthalmology
• Anatomy
• Imaging Technology

Background:

• Anterior segment optical coherence tomography (AS OCT) is crucial for visualizing ocular structures.
• Identifying key landmarks like the trabecular meshwork (TM) and Schlemm's canal (SC) is vital for understanding glaucoma pathophysiology.
• A novel landmark, the band of extracanalicular limbal lamina (BELL), adjacent to SC, has been proposed.

Purpose of the Study:

• To identify and characterize three angle landmarks: TM, SC, and the novel BELL, using AS OCT.
• To assess the visibility of these landmarks in relation to demographic and clinical factors.
• To correlate AS OCT findings with pathological examination.

Main Methods:

• Retrospective review of AS OCT images from 153 participants (303 angles).
• Evaluation by masked readers for the presence of TM, SC, and BELL.
• Logistic regression analysis to determine factors influencing landmark visibility.
• Pathological correlation on 5 enucleated eyes.

Main Results:

• The BELL outer border was visible in 95% of angles, TM in 73%, and SC in 40%.
• BELL visibility was higher in white individuals and eyes with a Spaeth gonioscopy grade of E.
• TM and SC visibility were significantly higher in temporal versus nasal angles and SC in open versus narrow angles.

Conclusions:

• A novel AS OCT landmark, the BELL, adjacent to SC, was identified and validated pathologically.
• The BELL was highly visible, suggesting its potential utility in AS OCT imaging.
• Further research is needed to elucidate the pathophysiological significance of the BELL.