Progression rate to primary angle closure following laser peripheral iridotomy in primary angle-closure suspects: a...

Area of Science:

• Ophthalmology
• Glaucoma Research
• Anatomic Studies of the Eye

Background:

• Primary angle closure suspects (PACS) are at risk of developing primary angle closure (PAC) and subsequent vision loss.
• Laser peripheral iridotomy (LPI) is a common intervention to manage occludable angles.
• Understanding the long-term efficacy of LPI in preventing PAC progression is crucial for clinical management.

Purpose of the Study:

• To determine the progression rate (PR) to primary angle closure (PAC) after laser peripheral iridotomy (LPI) in primary angle closure suspects (PACS).
• To evaluate the anatomical changes in the iridocorneal angle following LPI.
• To assess the impact of LPI on intraocular pressure (IOP) and the incidence of acute angle-closure glaucoma (AACG).

Main Methods:

• A prospective, randomized controlled trial involving 134 bilateral PACS patients.
• PACS defined by gonioscopic non-visibility of the posterior trabecular meshwork for ≥180 degrees.
• One eye per patient underwent LPI; gonioscopy and IOP measurements were taken at baseline, day 7, and 12 months post-procedure.

Main Results:

• At 12 months, 93.7% of LPI-treated eyes showed some angle opening, but 67.0% still had ≥180 degrees of angle closure.
• The progression to PAC was 3.75% in untreated eyes (one developed AACG), versus 2.5% in LPI-treated eyes (no AACG or peripheral anterior synechia).
• Mean IOP remained similar between treated (15.5±2.9 mm Hg) and untreated eyes (P=0.834) at 12 months.

Conclusions:

• LPI effectively opens occludable angles in the majority of PACS eyes, improving the anatomical configuration.
• Despite angle opening, a significant proportion (67%) of treated eyes maintained substantial angle closure.
• LPI demonstrated a trend towards reduced progression to PAC and AACG compared to untreated eyes.