Analysis of Telehealth Records Finds Post-dilation Angle Closure Rate Extremely Low

Some medical providers outside of eye care are sometimes wary of angle closure risks from pupil dilation and avoid the procedure as a result. This analysis found a rate of just 2.4 incidents per 100,000 dilations. Photo: Joseph W. Sowka, OD. Click image to enlarge. Despite the clear diagnostic benefits of pharmacologic dilation, its use is not widely adopted by non-eyecare medical professionals primarily due to concerns about triggering an acute angle closure (AAC) attack, an ophthalmic emergency that can lead to dramatic rise in intraocular pressure (IOP), rapid glaucomatous damage and irreversible vision loss.Researchers based out of Los Angeles believed that there was a further need to evaluate the safety of pharmacologic dilation, particularly in high-volume screening settings serving diverse populations. Their study, which was published last week in JAMA Ophthalmology, addressed these knowledge gaps by assessing AAC risk after pharmacologic dilation using data from the Los Angeles County Department of Health Services (DHS) Teleretinal Diabetic Retinopathy (DR) Screening program. They found that, among 84,008 patients and 168,796 dilations, there were four cases of medical record–confirmed AAC. Incidence was 2.4 per 100,000 dilations or 4.8 per 100,000 patients. The AAC risk was 2.4 per 100,000 dilations (0.002%) or 4.8 per 100,000 patients (0.005%).“These findings support the safety of mydriatic fundus photography in teleretinal screening programs and the use of ICD-9 and ICD-10 codes in claims-based studies on AAC,” the researchers wrote in their paper. “It is imperative to continue the discussion on how to balance the benefits of dilation for earlier and more accurate detection of eye disease against the very low risk of AAC after dilation.”1Eligible participants were DHS patients who underwent teleretinal screening by dilated fundus photography (either tropicamide 1.0% or 0.5%) over a period of almost 10 years. Potential AAC cases were identified using ICD codes for angle closure, including AAC glaucoma, primary angle-closure glaucoma and anatomical narrow angle within three months of dilation. The team then identified all urgent care, emergency department, and eye clinic encounters within the next calendar day after teleretinal DR screening and encounters with CPT codes for iridectomy/iridotomy or lens extraction within 14 calendar days of teleretinal DR screening. Manual medical record review was conducted to verify AAC cases and extract clinical information. Of these included patients, 55.1% were women, and the mean age was 55.4 years.All four cases were women who were phakic, had narrow angles in the nonpresenting eye identified on gonioscopy and presented within one day with AAC symptoms, including eye pain and blurry vision. All AAC attacks occurred in phakic eyes, highlighting the crucial role the lens plays in pupillary block and angle closure mechanisms.“Interestingly, two of four cases were younger than 50 years old; this finding appears to implicate non-lens-related mechanisms (e.g., plateau iris, thick iris roll) over lens-related mechanisms (e.g., pupillary block, high lens vault) in the pathogenesis of AAC, which remains poorly understood,” the researchers noted in their paper. “In addition, one case occurred in an Asian patient, a population group that comprised only 6.3% of the cohort.”The researchers speculated that all teleretinal DR screening patients received detailed AAC return precautions at the time of dilation, which may explain why all four cases presented shortly after AAC onset. They received prompt ophthalmic care and had good visual outcomes despite potential barriers to care in this under-resourced safety net health system. “These outcomes highlight the importance of patient education at the time of screening and the overall safety of the LAC DHS teleretinal DR screening program, even when complicated by a rare AAC attack,” they concluded."The team emphasized that further discussion about the safety of pharmacologic dilation is crucial for optimizing teleretinal screening workflows. Future research should also aim to identify factors conferring greater risk of AAC and to develop convenient diagnostic tools, possibly using OCT imaging, to identify individuals in whom pharmacologic dilation should be avoided.1A commentary, also published in JAMA Ophthalmology, noted that participants in this study received a mean number of one dilation per eye, while patients with diabetes undergoing regular screening typically require multiple pupil dilations. The long-term evaluation of progression to primary angle closure or AAC with repeated dilation in high-risk patients remains a valuable endeavor for future studies.“While this study supports the general safety of routine pupil dilation for diabetic retinopathy screening, longitudinal assessment of IOP and monitoring of angle changes may still be useful to evaluate the effects of repeated dilation in patients undergoing regular teleretinal screening,” the commentary authors wrote.2 Click here for the journal source and here for the commentary. 1. Lang TZ, Xu BY, Li Z, et al. Acute angle closure incidence in a large countywide safety net teleretinal screening program. JAMA Ophthalmol. September 18, 2025. [Epub ahead of print].2. Chong RS, Aung T. Assessing the risk of acute angle closure. JAMA Ophthalmol. September 18, 2025. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.