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High-tech metrics are not needed to evaluate the long-term risk that asymptomatic patients with primary angle-closure suspect (PACS) will proceed to glaucoma, data from a Chinese randomized trial showed.

In 377 patients with PACS eyes, 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, reported Wei Wang, MD, PhD, of Sun Yat-sen University in Guangzhou, China, and colleagues in .

"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 in New York City, told MedPage Today. Tsai, who penned a accompanying the study, added that the findings support the potential option of conservative management of PACS instead of always turning to laser peripheral iridotomy (LPI).

Study co-author David Friedman, MD, PhD, MPH, of Massachusetts Eye and Ear and Harvard Medical School in Boston, explained that "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."

While PAC is linked to angle-closure glaucoma, PACS is much more common, he told MedPage Today. "The main concern is that PACS will lead to glaucoma if left untreated."

Wang, Friedman, and colleagues aimed to understand whether examination via AS-OCT would improve predictive models compared with clinical exam alone.

"AS-OCT is an imaging modality that allows for visualization of the angle," said Friedman. "Without AS-OCT, the doctor has to put a mirrored lens on the eye to image the angle. This can lead to distortion and is subjective. AS-OCT allows for more quantitative measurements."

The investigators examined data from the , a single-center randomized clinical trial that began in 2008 and tracked 889 patients ages 50 to 70 years who had bilateral PACS and were treated with early LPI in one randomly selected eye. That study did not support the widespread use of LPI as a preventive strategy, since it "demonstrated that very few people diagnosed with PACS ever go on to develop angle-closure glaucoma," Friedman said.

For the current study, the researchers assessed data on 377 untreated PACS eyes, 25% of which progressed to PAC over 14 years; mean age of the patients at baseline was 58 years, and 84% were women.

Adjusted analysis showed that higher IOP (OR 1.14 per 1-mm Hg increase, 95% CI 1.04-1.25), shallower central ACD (OR 0.81, 95% CI 0.67-0.97 per 0.1-mm increase), and shallower limbal ACD (OR 0.96, 95% CI 0.93-0.99 per 0.01 increase in peripheral corneal thickness) at baseline were associated with 14-year risk of progression from PACS to PAC.

A prediction model based on IPO and ACD measurements showed "moderate" performance (area under the receiver operating characteristic curve [AUROC] 0.69, 95% CI 0.63-0.75), the researchers reported.

And models that incorporated IOP, central ACD, and either light-room trabecular iris space area (TISA; at 500 μm), light-room angle recess area (ARA; at 750 μm), or dark-room TISA (at 500 μm), demonstrated similar performance:

• Light-room TISA: AUROC 0.70 (95% CI 0.64-0.76)
• Light-room ARA: AUROC 0.70 (95% CI 0.64-0.76)
• Dark-room TISA: AUROC 0.69 (95% CI 0.62-0.75)

Friedman said the finding that only a fourth of patients developed PAC over 14 years "are very important and support not doing iridotomy in all PACS eyes."

"The models show that while we have some ability to predict who is at highest risk of worsening based on presenting characteristics, our prediction is not that precise," he added. "Overall, the fact that shallower anterior chamber and narrower angles are at greater risk supports clinical impressions and could lead some with very narrow angles or very shallow anterior chambers to elect to have prophylactic iridotomy."

Moving forward, "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.

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 onabotulinumtoxinA (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.

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