Why early cataract surgery may help glaucoma later

August 15, 2013

Cataract surgery not only can result in a reduction of IOP, it also provides benefits for future management of glaucoma.

Take-Home

Cataract surgery not only can result in a reduction of IOP, it also provides benefits for future management of glaucoma.

Dr. Singh

By Fred Gebhart; Reviewed by Kuldev Singh, MD, MPH

Stanford, CA-A treatment opportunity exists to lower IOP by an average of 3 to 4 mm Hg for at least 3 years. But this treatment is not a drug, it is clear corneal phacoemulsification.

The treatment is generally safe, cost-effective, may improve vision in more than 90% of patients, and may improve the margin of safety for future glaucoma surgery.

If such a therapeutic profile could be achieved with an eye drop, it would be a blockbuster, said Kuldev Singh, MD, MPH, professor of ophthalmology and director, Glaucoma Service, Stanford University School of Medicine, Stanford, CA.

“Cataract surgery should be considered an IOP-lowering procedure,” Dr. Singh said. “All things being equal, for the patient who is on the fence with regard to undergoing cataract surgery due to vision loss from lens opacification, the added benefit with regard to subsequent glaucoma care may help tip the balance in favor of surgery.

“Such treatment would not only be expected to improve vision, but on average, would result in better IOP control and/or reduction in dependence upon glaucoma medications,” he said. “Cataract surgery can change the trajectory of glaucomatous disease.”

Treatment background

Cataract surgery is already the most commonly performed IOP-lowering procedure.

While there are fewer than 100,000 glaucoma surgeries in the United States annually, Dr. Singh said, an estimated 15% of the 3.5 million patients who undergo cataract surgery also have primary open-angle glaucoma or ocular hypertension.

That is about 500,000 patients who typically benefit from lower IOP following phacoemulsification.

Multiple studies and meta-analyses have shown similar IOP-lowering effects from cataract surgery, Dr. Singh said.

Some ophthalmologists may not recognize this benefit and hold off on cataract surgery until vision loss is more severe, he said.

While there must be vision loss impacting some activities of daily living to consider cataract surgery, the visual threshold for surgery should be different in patients with co-existent glaucoma who will likely derive added benefit from lower postoperative IOP.

The positive impact on IOP has not yet been fully integrated in surgical decision-making.

Benefits of adding IOP lowering

The time has come, Dr. Singh said, to expand the medical necessity for cataract surgery in patients who also have glaucoma and could benefit from the additional IOP lowering without adversely impacting future treatment options in most cases.

The IOP lowering with cataract surgery is blebless.

Several new adjunctive treatments with cataract surgery have been developed that also lower IOP without bleb formation, a profile that is clearly better than bleb-forming surgery in terms of long-term safety.

It is equally important to note that modern clear corneal temporal phacoemulsification leaves the superior conjunctiva untouched for future trabeculectomy and tube implantation.

“If you take out the cataract in a patient who may need glaucoma [surgery] in the future, you have really preserved all of your future options on the glaucoma surgery side,” Dr. Singh said. “You have very little to lose and enormous benefits to gain by early, rather than late, cataract removal in such patients.”

How it works

The key, he said, is to evaluate the visual need initially for cataract surgery.

If patients meet the minimum threshold for cataract surgery, ophthalmologists can factor in the potential benefit of a sustained IOP lowering, particularly in those receiving glaucoma medications with associated costs, side effects, and issues of noncompliance.

“You may want to let your patients know that if you take out the cataract, their vision will improve and, on average, their IOP will be better controlled,” Dr. Singh said. “For patients who are already [taking] glaucoma medication, they will likely be less dependent on eye drops after glaucoma surgery.

“You should also, however, share the possibility that IOP may increase in some individuals following cataract surgery and urgent glaucoma surgery may be required in a small subset of such patients,” he said. “Those with severe and/or medically uncontrolled glaucoma may sometimes require glaucoma surgery prior to cataract surgery or combined phaco trabeculectomy.”

Looking to the future

The rationale for early cataract surgery will only become stronger as new minimally invasive devices to lower IOP become available.

Some of these devices have already been approved for use, and others are still at various stages of the regulatory approval process in the United States.

The extent to which these devices and procedures lower IOP beyond the effect of phacoemulsification alone will impact the threshold for the performance of cataract surgery, Dr. Singh said.

“Cataract surgery commonly makes subsequent glaucoma care easier and rarely makes it more difficult,” Dr. Singh said. “The visual improvement from cataract surgery is apparent to all, but the benefits in terms of glaucoma management require further dissemination in the ophthalmology community.”

Kuldev Singh, MD, MPH

E: Kuldev.Singh@Stanford.edu

Dr. Singh is a consultant to Alcon Laboratories, Allergan, Bausch + Lomb, Ivantis, and Transcend Medical.

 

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