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Managing combined cataract, glaucoma cases a frequent challenge for clinicians
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 Richard L. Lindstrom |
Managing patients with combined cataract and glaucoma is a frequent challenge for the comprehensive ophthalmologist. Reviews of Medicare coding data suggest that 15% to 20% of patients operated for cataract in the U.S. have associated glaucoma or ocular hypertension. Since we perform approximately 3,200,000 cataract operations per year in the U.S., surgeons need to develop an appropriate plan for managing this important subset of patients.
My classical teaching favored glaucoma filtration or tube shunt surgery first, followed by cataract surgery later in the most severe cases of glaucoma, a combined phacoemulsification and trabeculectomy in the moderate cases, and perhaps phacoemulsification first for the milder cases and those with ocular hypertension.
A number of factors in the past decade have changed my thinking regarding this approach. First, medical therapy has advanced in efficacy, and we now have a once-a-day topical medication that can lower IOP 20% to 30% with a good safety profile. Second, phacoemulsification has evolved into an extremely safe clear corneal approach that preserves normal conjunctiva for any subsequently needed glaucoma surgery. Third, I have learned that cataract surgery alone lowers IOP more than I had previously appreciated in the patient with elevated IOP. In addition, reasonable studies repeated by several researchers suggest that this IOP lowering is sustained for up to 10 years. The last factor, yet to mature, is the large number of minimally invasive surgical approaches being developed that seem capable of lowering IOP and medication burden when combined with cataract surgery, with almost no meaningful risk.
The severity of preoperative glaucoma damage and the target pressure desired for each patient mandate careful thinking and a customized approach, but I have definitely decreased the number of patients for whom I recommend combined phaco-trabeculectomy, and I almost never recommend the patient start with filtration surgery.
Why the change? Primarily it is a result of a better understanding of the power of phacoemulsification alone in reducing IOP and the fact that this can be enhanced by generally tolerable topical therapy. Also, phaco-IOL enhances quality of life for most patients, whereas trabeculectomy or tube shunt too often reduces it. While some recommend a combined procedure to mitigate the risk of transient IOP spike with phaco, trabeculectomy and tube shunt as performed today have a similar risk of early postop pressure spike as we utilize surgical approaches to avoid the even more feared hypotony. But phaco-IOL plus one medication can give most patients an 8 mm Hg to 12 mm Hg reduction in IOP and an enhanced quality of life.
What about phaco combined with trabeculectomy or tube shunt? The recent tube vs. trabeculectomy study demonstrated that both procedures generate approximately a 13 mm Hg drop in IOP when combined with a single medication. Unfortunately, this greater IOP drop was achieved at the expense of a 40% to 60% complication rate, including many sight-threatening complications, and a lifetime potential for late complications such as bleb infection.
In select cases with vulnerable nerves where target pressures require this risk, a combined procedure is definitely indicated, but I find those cases in my practice to be rare indeed. And it is possible to argue that little is lost by trying phaco-IOL combined with medical therapy first, before sentencing the patient to the lifetime morbidity of trabeculectomy or tube shunt. After all, sequential therapy using the safest modalities first is a classic teaching in medicine.
While my patient population with cataract and glaucoma is that of a comprehensive ophthalmologist — most patients are going blind from cataract and happen to have glaucoma — the number of my patients who require filtration surgery each year is less than 1%. The consultative glaucoma specialist clearly sees a different cohort of patients, where blindness is being caused by progressive glaucoma damage in spite of maximally tolerated medical therapy and the patient happens to have cataract. These patients are a different story. But for me, phaco-IOL alone is my most frequent glaucoma surgery, and it is fun to add significant reduction in IOP to the other enormous quality-of-life-enhancing features of well-done modern cataract surgery.
In the future, I am hoping for a minimally invasive glaucoma surgery that can enhance the IOP drop associated with cataract surgery, preferably with no additional risk. I would love to reduce medication burden to zero and to achieve an average target IOP of 12 mm Hg to 14 mm Hg rather than 16 mm Hg to 18 mm Hg, reducing the risk of progressive glaucoma damage to near zero. Several companies are investing heavily to give us such a minimally invasive glaucoma procedure that will be compatible with cataract surgery by reducing aqueous production or moving aqueous into Schlemm’s canal, the suprachoroidal space or even under the conjunctiva in a safe and effective way. I am impressed with the early outcomes generated by these approaches and look forward to accessing them in the future.
Still, for now, for me, phaco-IOL is my most trusted partner in managing the patient with combined cataract and glaucoma.