Appositional angle closure in Chinese with primary angle closure and primary angle closure glaucoma after laser...

Area of Science:

• Ophthalmology
• Anatomic studies
• Glaucoma research

Background:

• Primary angle closure (PAC) and primary angle closure glaucoma (PACG) are prevalent conditions, particularly in Asian populations.
• Laser peripheral iridotomy (LPI) is a common treatment to improve aqueous humor flow.
• Understanding residual or post-treatment angle closure is crucial for effective management.

Purpose of the Study:

• To determine the prevalence of appositional angle closure (AAC) after LPI in Chinese patients with PAC and PACG.
• To investigate the anatomic characteristics contributing to AAC pathogenesis.
• To evaluate the functional significance of AAC using darkroom provocative tests (DRPT).

Main Methods:

• A cross-sectional observational study enrolled 134 Chinese patients with PAC and PACG post-LPI.
• Ultrasound biomicroscopy (UBM) assessed iridocorneal angles in darkness, excluding peripheral anterior synechia (PAS).
• Darkroom provocative tests (DRPT) were performed to assess dynamic angle changes.

Main Results:

• Appositional angle closure (AAC) was observed in 63.4% of eyes (≥ 1 quadrant UBM).
• In quadrants without PAS, AAC was present in 32.8%, with plateau iris (44.7%), anteriorly inserted iris (13.2%), and thick iris (13.2%) as primary contributors.
• DRPT showed a significantly higher positive rate in eyes with ≥ 2 quadrants of AAC (37.5%) compared to those with ≤ 1 quadrant (16.9%).

Conclusions:

• AAC is highly prevalent (approx. two-thirds) in Chinese PAC and PACG patients post-LPI.
• Plateau iris, thick peripheral iris, and anteriorly inserted iris are significant anatomical factors contributing to AAC.
• DRPT suggests AAC may have greater functional implications than plateau iris alone in these patients.