Laser Peripheral Iridotomy Reduces Acute Angle Closure Attack Following Mydriasis

Ophthalmologist applying eye drops
Ophthalmologist applying eye drops.
Prophylactic laser peripheral iridotomy reduces the low risk of an acute angle closure attack in glaucoma suspects even further.

The risk of incident acute angle closure (AAC) attack in eyes with primary angle-closure suspects (PACS) following mydriasis is extremely low, and prophylactic laser peripheral iridotomy (LPI) reduces the risk further, researchers found in a study published in Ophthalmology Glaucoma.

Researchers conducted a study to evaluate the risk of AAC in patients who were PACS. They enrolled 889 patients (mean age 59.3±5.0 years, 82.9% women) who were PACS in the analysis. Participants had LPI performed in 1 eye while the fellow eye served as a control. Investigators recorded AAC symptoms following 6 pupillary dilations over 6 years of follow-up. 

Overall, 5 individuals experienced AAC (1 bilateral, 4 unilateral) attacks. Their quadrants were closed on gonioscopy at baseline. The bilateral attack occurred at 2 weeks following dilation. The 4 unilateral attacks occurred in untreated eyes (2 before 36- and 72-month visits and 2 at 54- and 72-months visits).

The researchers found that the incidence of AAC was lower among LPI-treated eyes (0.22 per 1000 eye-years; 95% CI, 0.31-1.57 eye-years) compared with untreated eyes (1.11 per 1000 eye-years; 95% CI, 0.46-2.66 eye-years).

No AAC attacks occurred without mydriasis in the LPI-treated group, and 2 AAC attacks occurred without mydriasis in the untreated group (0.44 per 1000 eye-years; 95% CI, 0.11-1.77 per 1000 eye-years).

Patient IOPs returned to normal after receiving medications followed by LPI. Vision improved and no participants required further surgical intervention.

Investigators noted that eyes that experienced AAC attacks tended to be more hyperopic and have shallow anterior chambers compared with those that did not have AAC attacks.

“Overall, our results suggest that it is generally safe to dilate patients after an iridotomy,” according to the researchers. “Eyes without an iridotomy did have a small but real risk of AAC with repeated mydriasis. Therefore, it is reasonable to consider LPI for people who require frequent dilation, such as patients with diabetes mellitus who must be monitored closely for sight-threatening diabetic retinopathy.”

Study limitations include potential confounding due to medications and the exclusive enrollment of individuals who are Chinese.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.


Friedman DS, Chang DS, Jiang Y, et al. Acute angle closure attacks are uncommon in primary angle-closure suspects: the Zhongshan angle closure prevention trial. Ophthalmol Glaucoma. Published online May 11, 2022. doi:10.1016/j.ogla.2022.04.003