Acute Angle Closure Incidence in a Large Countywide Safety Net Teleretinal Screening Program

Pharmacologic pupillary dilation is vital for eye disease screening but is often avoided due to concerns about triggering acute angle closure (AAC), a sight-threatening ophthalmic emergency.

To assess AAC incidence after dilation and validate the use of International Classification of Diseases (ICD) codes for identifying AAC cases.

This retrospective cohort study used data from a primary care-based teleretinal diabetic retinopathy screening (TDRS) program. Eligible participants were Los Angeles County Department of Health Services patients who underwent teleretinal screening by dilated fundus photography between August 23, 2013, and March 1, 2024. Potential AAC cases were identified using ICD codes for angle closure, including AAC glaucoma, primary angle-closure glaucoma, and anatomical narrow angle, within 3 months of dilation. All urgent care, emergency department, and eye clinic encounters within the next calendar day after TDRS and encounters with Current Procedural Terminology codes for iridectomy/iridotomy or lens extraction within 14 calendar days of TDRS were also identified. Manual medical record review was conducted to verify AAC cases and extract clinical information. Data were analyzed from July 2024 to June 2025.

Dilation with tropicamide, 1.0%, or tropicamide, 0.5%.

Cumulative incidence of AAC after dilation.

Of 84 008 included patients, 46 255 (55.1%) were female, and the mean (SD) age was 55.4 (10.7) years. There were a total of 168 796 dilations, with a mean (SD) of 2.01 (1.50) dilations per patient. Manual medical record review confirmed 4 AAC cases after dilation: 3 coded as AAC glaucoma and 1 as anatomical narrow angle. The AAC risk was 2.4 (95% CI, 0.05-4.69) per 100 000 dilations (0.002%) or 4.8 (95% CI, 0.10-9.43) per 100 000 patients (0.005%). All 4 AACs occurred in female patients, had narrow angles in the nonpresenting eye on gonioscopy, and presented within 1 day with AAC symptoms, including eye pain and blurry vision.

AAC risk was less than 1 in 40 000 per dilation in a high-volume TDRS program serving a diverse safety net population, supporting the overall safety of dilation in this setting. Further discussion about AAC risk as a contraindication to dilation is warranted.