Rethinking management strategies for PAC, PACG

Results of the EAGLE study support clear-lens extraction as initial intervention for eyes with primary angle-closure glaucoma (PACG) or primary-angle closure (PAC) and high IOP, said David S. Friedman, MD, PhD, at the 2018 ASCRS Glaucoma Day.

“Cataract surgery makes a lot of sense in these patients, and I offer it regardless of lens status,” said Dr. Friedman, Alfred Sommer Professor Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore.

“There are risks with clear-lens extraction, and you may be facing a patient in whom a bad outcome occurs because you recommended the lens surgery as opposed to iridotomy,” he said. “However, you have to keep in mind that iridotomy leads to another pathway with many adverse outcomes.

“And, another important consideration is that these patients are in their 60s and will have cataract surgery sometime in the next decade and many in the next 5 years,” Dr. Friedman said. “So, with lens surgery, you are really just moving forward the risk and not creating a new risk out of nowhere.”

EAGLE, funded by the Medical Research Council was a multicenter study with 419 participants enrolled at 23 sites in the United Kingdom, 7 sites in Asia, and 1 site in Australia.

Eligible patients were aged 50 years and older, phakic in the affected eye with no cataract, and had newly diagnosed PACG with IOP ≥21 mm Hg or primary angle closure PAC with IOP ≥30 mm Hg and at least 180º of angle closure. Patients were excluded if they had a previous diagnosis of acute angle closure attack, severe glaucoma, were nanopthalmic, or had previous laser or ocular surgery.

Patients were randomly assigned 1:1 to undergo phacoemulsification or laser peripheral iridotomy (PI). Patients with both eyes eligible received the same intervention bilaterally, but the index eye was the one with more advanced disease. The study had follow-up to 3 years.

The enrolled subjects were mainly European in origin, but 29% were Chinese. The participants had a mean age of 67 years, slightly over one-third had PAC, and the rest were diagnosed with PACG. Mean baseline IOP was 28.9 mm Hg.

The co-primary endpoints for the study were patient-reported health status assessed with the European Quality of Life-5 Dimensions questionnaire (EQ-5D), IOP, and incremental cost-effectiveness ratio per quality-adjusted life-year gained at 36 months after treatment. The EQ-5D assesses five dimensions of health-mobility, self-care, usual activity, pain/discomfort, and anxiety/depression-based on ratings of no, some, or extreme.

The analysis of EQ-5D scores showed a statistically significant difference favoring clear-lens extraction. While there was no change in mean EQ-5D score from baseline to 3 years in the lens extraction group, there was worsening in the laser PI group.

“These results are not totally surprising,” Dr. Friedman said. “Overall, quality of life was better maintained after taking out the lens from these patients who are hyperopic and probably have some lens opacity than if nothing was done.”

Mean IOP decreased in both groups, but there was a statistically significant difference favoring clear-lens extraction. Mean IOP was 1.18 mm Hg lower in the clear-lens extraction group than in eyes randomized to laser PI, and mean daily medication use was also less in the lens extraction group than in the laser PI group, 0.4 versus 1.3, respectively.

The cost-effectiveness analysis also favored clear-lens extraction with the incremental cost-effectiveness ratio being £14,284 per quality-adjusted life-year gained for clear-lens extraction versus laser PI.

Secondary surgery and complications

Dr. Friedman said the differences between groups in the need for additional glaucoma surgery and in complication rates were particularly interesting. Among 211 eyes in the laser PI group, 24 underwent a glaucoma surgical procedure, including 16 lens extractions, whereas a single eye in the clear-lens extraction group had additional glaucoma surgery.

Intraoperative complications were also fewer in the clear-lens extraction group.

“There is a risk of posterior capsule rupture during lens extraction,” Dr. Friedman said. “Because these are relatively soft lenses, posterior capsule rupture is rare, and so the risk of a bad surgical outcome is low.”

Postoperative complications were mostly minor in both groups, and the need for intraocular surgery for complication management was low in both groups but higher after clear-lens extraction compared with laser PI, 1.4% versus 0.5%.

However, the rate of irreversible loss of >10 ETDRS letters was higher in the laser PI group than in eyes that had clear-lens extraction, 1.4% versus 0.5%.

Strengths and weaknesses

Dr. Friedman noted that while the study was well-conducted, had a large sample size, and excellent retention, it had some limitations. It was not fully masked, definitions of complications were not standardized, and the generalizability of the results to Asian populations is not clear.

“It is possible that there may be a difference between Chinese and non-Chinese populations that were not detected,” he said. “In addition, the PAC arm may have had less benefit, but the study was not powered to compare the two interventions in the PAC and PACG groups alone.”