Consider cataract surgery for glaucoma intervention

San Francisco-Cataract surgery is already the most-used intervention for glaucoma. A growing number of glaucoma specialists want to see timely glaucoma surgery accepted and reimbursed as an appropriate intervention for the long-term management of glaucoma.

“If we had a drug that lowered IOP by 4 mm Hg for at least 3 years and improved vision in more than 90% of patients who used it, we would have a blockbuster,” said Kuldev Singh, MD, MPH, professor and chief of the Glaucoma Service at Stanford University, Stanford, CA.

“We don’t have that drug, but we have clear corneal temporal phacoemulsification that fits the profile,” Dr. Singh said. “We are moving toward earlier use of glaucoma surgery for patients with primary open-angle glaucoma (POAG).”

The move from traditional glaucoma management to cataract surgery for glaucoma is already under way in Asia. Multiple studies have demonstrated the safety and efficacy of glaucoma surgery for acute and chronic angle glaucoma, Dr. Singh noted. Other studies suggest that phacoemulsification is equally safe and equally effective for POAG.

One of the largest trials to date, the Ocular Hypertension Treatment Study, found a consistent reduction in IOP by 3.5 to 4 mm Hg 3 years after cataract surgery. Other studies over the past decade have seen similar results, Dr. Singh said. Similar IOP lowering has been seen in eyes without glaucoma and IOP lowering is more pronounced in eyes with exfoliation syndrome.

As might be expected, he said, the pressure-lowering effect of cataract surgery is greater in eyes with a higher preoperative IOP. Postoperative IOP can be very accurately predicted based on preoperative IOP and anterior chamber depth.

While it is clear that cataract surgery lowers IOP, the mechanism of action is not entirely clear, he continued. Increasing fluid flow following surgery may help to clean or open the trabecular meshwork. Cataract surgery may also act on inflammatory processes. More likely is a different combination of all three effects in different patients depending on their individual characteristics.

IOP lowering is no surprise to cataract surgeons. There are fewer than 100,000 glaucoma procedures performed annually in the United States compared with 3.5 million cataract operations. About 15% of patients with cataracts also have glaucoma, Dr. Singh estimated. That translates in about 500,000 patients with glaucoma who benefit from lowered IOP every year, five times the number of patients with glaucoma who undergo glaucoma procedures.

“Whether or not you believe cataract surgery is an effective glaucoma procedure, it is clearly the most commonly performed IOP-lowering procedure,” Dr. Singh said. “We are moving toward earlier surgery for elevated IOP.”

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