Treatment has shifted away from combined cataract-glaucoma procedures

Issue: April 25, 2009

ByRichard L. Lindstrom, MD

Richard L. Lindstrom

Next to age-related macular degeneration, glaucoma is the most common comorbidity encountered by the surgeon planning cataract surgery. If one includes all ocular hypertensives with a preoperative pressure of 22 mm Hg or greater, glaucoma suspects and patients with all forms of glaucoma, as many as 15% of patients coming to cataract surgery have one of these associated diagnoses.

In the United States, we currently perform approximately 3.2 million cataract operations per year, so American cataract surgeons must decide how to manage both problems 480,000 times each year. In the world, where as many as 15 million cataract operations are performed annually, this decision-making process is confronted 2.25 million times a year.

Ten years ago when confronted with the patient with combined cataract and glaucoma, I was very aggressive in recommending a combined procedure, usually phaco/IOL/trabeculectomy. Now I recommend this option very infrequently. Why the change?

First, cataract surgery has advanced significantly, and with the advent of a clear corneal microincision approach, the conjunctiva is spared for any possible future glaucoma procedure. Second, our medical treatment options have increased and improved, and especially with the addition of the prostaglandin analogues, we have a very effective once daily drop for lowering pressure. Finally, I have learned that crystalline lens removal and replacement with an IOL is in itself quite effective in lowering IOP when it is elevated.

While we have always known that cataract surgery results in some reduction in IOP, the classical teaching was that it was minimal, 1 mm Hg to 2 mm Hg, and transient, lasting only a year or so. Now we have learned that IOP reduction is proportional to preoperative IOP and significant, averaging 20% to 30% of the off-drops preoperative IOP. Thus, a patient with a preoperative pressure of 25 mm Hg off drops can anticipate a 5 mm Hg to 7 mm Hg drop in IOP with cataract surgery alone. Add one drop of a prostaglandin analogue giving another 20% drop, and we now have a pressure drop of 10-plus mm Hg. To me, a very impressive outcome without the risk of a combined procedure.

Of course, it does not work for everyone, but we can always do glaucoma surgery later when indicated in a fully healed uninflamed postoperative eye with a posterior chamber lens in place. Many would argue that glaucoma surgery is easier and generates better outcomes in this setting.

One danger that remains is the potential for a severe postoperative pressure spike that can be very dangerous in the patient with advanced glaucoma and a vulnerable nerve. Aggressive antihypertensive treatment including an intracameral miotic such as carbachol, topical application of ocular antihypertensives and judicious use of a carbonic anhydrase inhibitor orally can mitigate this risk. In highly vulnerable patients, an IOP check at 4 to 6 hours after surgery is also reasonable.

There clearly remain some patients in whom a combined approach is indicated, including the patient with very elevated IOP and a vulnerable nerve.As always, the surgeon’s clinical judgment and a surgical plan customized to each patient’s individual needs remain the hallmark of quality care. Still, today I find myself rarely recommending a combined procedure to my cataract patients with glaucoma.

In the future, development of newer, less invasive glaucoma procedures may tip the balance back toward a combined procedure, but for now cataract surgery alone with a drop or two of medical therapy when needed seems to be serving the majority of my patients admirably.