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Continued advancements needed for best treatment of glaucoma
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 Richard L. Lindstrom |
As we clinicians all know, glaucoma is a “lifetime sentence” for both the patient and the ophthalmologist who assumes responsibility for his or her care. For this reason, all mature practices and practitioners have a large cohort of glaucoma patients under their care.
The aging demographics of the U.S. population guarantee that we will all remain busy as the 78 million baby boomers pass by age 65 starting next year. Studies confirm that patients older than age 65 consume 10 times more care than those younger than 65, so the next 30 years will see ever increasing demands for our services.
Most well-controlled patients on medical therapy are seen twice yearly in my practice. Those with more severe disease or evidence of progression are seen more frequently, and a few patients with very mild well-controlled disease are seen just once a year. On one visit, I perform the usual vision testing, pressure, slit lamp and fundus examination combined with a visual field. On the other, I perform the usual examination plus an OCT/GDX or HRT of the disc.
A few clinical pearls worth mentioning include the fact that glaucoma is usually asymmetric in its presentation and progress. It is often possible to recognize a very subtle Marcus-Gunn afferent pupillary defect in the eye with more damage, and in some patients, this can be a tip-off to look more carefully at the glaucoma suspect/ocular hypertensive. In addition, asymmetry of more than 3 mm Hg in pressure or any asymmetry of the disc, especially the vertical cup, raises my index of suspicion.
I have learned to look more at the remaining disc tissue, rather than the classical cup size, starting inferior, then superior, then nasal, then temporal. Of course, a disc hemorrhage is always an important finding. Pachymetry has helped us better understand the at-risk patient. And a positive family history, especially on the maternal side, is important to me. Myopia, hyperopia with narrow angles and race are valuable clues. Gonioscopy is often missing when charts are reviewed, and we should all remember to perform this important test initially and as indicated.
Therapy in the U.S. is dominated by topical drops. It is interesting that the blockbuster drug Xalatan (latanoprost 0.005%, Pfizer) is scheduled to go off patent in 2011 and be available in a generic form. This means that we have not seen a new class of glaucoma drops in more than a decade. The most promising new class of drops appears the be the Rho-kinase inhibitors, which seem capable of increasing facility of outflow without the side effects of the classical miotics. They would be a welcome addition to our therapeutic armamentarium, but are in early-stage clinical trials and are years away from approval. We are seeing a few new combination drugs approved, which are helpful in regard to compliance.
In addition, argon laser trabeculoplasty and selective laser trabeculoplasty are widely available.
The most exciting clinical development is in the arena of surgical treatment, with nearly a dozen new techniques and devices advancing to compete with the classical trabeculectomy and tube shunt. The recently completed Tube vs. Trabeculectomy Study confirmed the excellent efficacy of these two procedures. Both achieved a mean pressure lowering of approximately 13 mm Hg when combined with a single topical medication. Unfortunately, the complication rate remains high, even in the most experienced of surgeons’ hands.
We desperately need effective surgical procedures for glaucoma that are effective but safer than the classical mitomycin trabeculectomy or tube shunt. Hopefully one or more of the many new devices and surgical procedures currently working their way through the regulatory process will move us into an era in which we can more confidently offer a surgical alternative to our patients at an earlier stage in their disease.
In my opinion, the most successful of these new devices and/or procedures will be synergistic with cataract surgery and lens implantation, as this is an ideal time to fix both the handicap of cataract and the sight-threatening disease glaucoma. While medical therapy remains the cornerstone of current treatment, I look forward to the day when my patients have a surgical alternative that is as safe and effective as LASIK in the young myope or phacoemulsification and posterior chamber lens implantation in the senior with cataract.