For PACS (primary angle-closure suspect) eyes, a simple clinical exam is enough to predict long-term glaucoma risk

Term:

Iridotomy, or laser peripheral iridotomy (LPI): a method by which ophthalmologists create a microscopic hole in the iris using a laser to open the angle (or internal drainage system of the eye) in patients with narrow or closed angles.

Anterior chamber: the aqueous humor-filled space inside the eye between the iris and the cornea’s innermost surface. Determining the anterior chamber depth is important in estimating the risk of angle closure glaucoma. 

There are two main types of glaucoma, primary open-angle and primary angle-closure. While angle-closure is less common than open-angle glaucoma, it usually causes more vision loss if it is not treated properly.  Primary angle closure suspects (PACS) are persons who have not yet developed angle-closure, but have features that make it more likely to occur later.  Primary angle closure (PAC) “is identified when an eye doctor examines the outflow of fluid from the front of the eye (anterior chamber), and the normal area of outflow (the trabecular meshwork) is not visible for at least 180 degrees,” explains David Friedman, MD, PhD, MPH, of Massachusetts Eye and Ear and Harvard Medical School, co-author of a new study. While PAC is linked to angle-closure glaucoma, PACS is much more common, he said. “The main concern is that PACS will lead to glaucoma if left untreated.”

“AS-OCT [anterior segment optical coherence tomography] is an imaging modality that allows for visualization of the angle,” said Friedman. Friedman and colleagues wondered whether adding AS-OCT would improve predictive models compared with clinical exam alone. For the current study, the researchers assessed data on 377 untreated PACS eyes from the Zhongshan Angle Closure Prevention trial, a 2008 clinical trial of 889 adult patients with bilateral PACS. The results suggest that OCT or other high-tech metrics are not needed to assess progression of a primary angle-closure suspect who is asymptomatic. The addition of anterior segment optical coherence tomography (AS-OCT) metrics didn’t boost the accuracy of models based on clinical analysis of intraocular pressure (IOP) and central and limbal anterior chamber depths (ACDs) for predicting the risk of progression to primary angle closure (PAC) at 14 years, wrote Wei Wang, MD, PhD, of Sun Yat-sen University in Guangzhou, China, and colleagues in JAMA Ophthalmology. “By doing a simple clinical examination, you can give the patient a prediction about their risk that’s as good as more sophisticated testing,” James Tsai, MD, MBA, president of the New York Eye and Ear Infirmary of Mount Sinai, told MedPage Today.

Importantly, the authors also found that only a fourth of patients developed PAC over 14 years. Tsai, who wrote a commentary accompanying the study, said that the findings support the potential option of conservative management of PACS instead of always turning to laser peripheral iridotomy (LPI). “These findings should encourage those who did not do so previously to reconsider why they do so many iridotomies and perhaps consider doing fewer and only on the highest-risk patients,” Friedman said. Tsai agreed, noting that too many ophthalmologists turn “automatically” to the laser treatment in asymptomatic patients even when eye pressure is in the normal range, there’s no evidence of optic nerve or visual field damage, and the patient hasn’t had narrow angle attacks (acute angle closure) . He said these patients can be followed conservatively and told to avoid drugs that dilate the eye such as antidepressants, the scopolamine patch, over-the-counter cold medications, and Botox injections. In addition, Tsai said, ophthalmologists can show patients how to use the flashlights on smartphones to reverse narrow angle attacks. The flashlights reverse the condition by triggering dilated eyes to constrict, he explained.

Study funding included the Natural Science Foundation of Guangdong Province and the Global STEM Professorship Scheme. Wang and Friedman reported no disclosures; a co-author reported grant support from the National Institute for Health Research Biomedical Research Center at Moorfields Eye Hospital and the Richard Desmond Charitable Foundation. Tsai reported no disclosures.

Source: Randy Dotinga, MedPage Today, January 22, 2024; see source article