Laser peripheral iridotomy for dark-induced angle closure changes: A proof-of-concept study

Area of Science:

• Ophthalmology
• Glaucoma Research
• Laser Surgery

Background:

• Dark-induced angle closure (AC) changes (DACC) represent a potential early stage of angle closure.
• Understanding DACC is crucial for preventing progression to AC glaucoma.

Purpose of the Study:

• To evaluate the outcomes of laser peripheral iridotomy (LPI) in phakic eyes diagnosed with DACC.
• To determine if LPI can favorably alter the course of DACC.

Main Methods:

• Phakic adult outpatients with DACC underwent bilateral YAG laser peripheral iridotomy (LPI).
• Baseline and 12-month follow-up included intraocular pressure (IOP) measurement, retinal nerve fiber layer (RNFL) thickness assessment, and gonioscopy in the dark.
• DACC was defined by gonioscopic findings of iridotrabecular contact (ITC) and/or a Shaffer angle ≤20° in the dark.

Main Results:

• 114 patients (mean age 59.6 years) were included; 92% had normal IOP without glaucoma.
• At 12 months, mean IOP decreased by 1.7 mmHg (P<0.001), and mean RNFL thickness increased by 0.42 μm (P=0.045).
• All patients demonstrated immediate anterior chamber deepening post-LPI; 47% had Shaffer angle ≤20° at baseline.

Conclusions:

• LPI demonstrated favorable outcomes in eyes with DACC, including reduced IOP and improved RNFL thickness.
• These findings suggest DACC is a clinically relevant entity indicative of early-stage angle closure.
• LPI may serve as a preventative strategy for angle closure and subsequent glaucoma.