Editorial

Glaucoma

Glaucoma is the subject of this issue. There is a wide range of thought-provoking articles consisting almost entirely of fresh material not to be found in standard textbooks. The tone is set with the lead article by Wat­son and Grierson; a long and important paper which deserves careful reading. These authors, drawing from deep clinical experience and consideration of experi­mental data in humans and animals, make a strong case for early surgical intervention in chronic open­angle glaucoma. They suggest that chronic medical therapy, if it causes underperfusion of the trabecular meshwork-outflow mechanism, may in the long run be deleterious and lead to a less medically manageable state. Watson advocates trabeculectomy if miotic therapy or timolol fails to achieve the desired round­the-clock pressure-lowering effect; he rarely adds acetazolamide or its cousins to his therapeutic regimen. In his view trabeculectomy is the procedure of choice because he has found that it generally works, has rela­tively low morbidity, and dampens diurnal fluctuations in the intraocular pressure. Successful surgery does seem to lead to underperfusion of the remaining tra­becular meshwork, but of course this does not matter if the filter remains patent. In my experience, tra­beculectomy, as advocated by the Cambridge duo of Watson and Cairns, has been an excellent replacement for the thermal sclerostomy, but it has a significant failure rate in our black population.

It is commonplace outside of the United States to eschew attempts at what we consider maximal medi­cal therapy for the treatment of chronic open-angle glaucoma. The reasons are many and include the great expense of the polypharmacy of maximal medical therapy, impracticality of using such therapies in many areas of the world, poor patient compliance; limited access to ophthalmologists, and most of all a genuine belief on the part of some ophthalmologists that surgery may be more beneficial for the patient than chronic medication.

Although few, I think, would argue that ocular hy­pertension-a condition still needing adequate defini­tion-should either not be treated or gently managed

medically, what about genuine glaucoma with field loss and cupping regardless of the level of intraocular pressure? Is this a medical or a surgical problem?

If surgery is now to be considered appropriate in managing early bona-fide chronic open-angle glauco­ma, what about the laser? The three articles on laser trabecular surgery in this issue suggest that this is a useful, relatively safe, and easily applied modality with small morbidity. To date, the procedure has been generally reserved for patients who are poorly con­trolled on maximally tolerated medicines. Since the technique is still to be refined and the reporting of results still limited, I believe that we must be cautious before turning our lasers loose on every human with borderline I.O.P. It is probably appropriate for glau­coma centers to consider scientific trials comparing laser trabecular surgery to medical treatment in early stage glaucoma. By the way, it is still not clear how the laser actually causes a reduction in I.O.P. Does it really tighten up the trabecular meshwork?

Laser iridotomy seems to be well tolerated by the human eye and has become the treatment of choice for managing the patient with narrow-angle glaucoma at least at the Wilmer Institute, and Quigley's data are most encouraging. Can one marshall any argument for chronic medical therapy in the narrow-angle patient when the laser seems such a safe way of achieving a cure?

Timolol is the subject of five articles, and the drug, although obviously useful in many adult-onset glau­coma patients, seems less valuable in the pediatric glaucoma population. Synthetic cannabinoids still have a long way to go before they become common-place medications in glaucoma management. Dipivalyl epinephrine may be toxic to the conjunctiva, but less so than epinephrine. Lichter suggests how one can reduce the side effects of carbonic anhydrase in­hibitors. In an elegant experiment Brubaker and col­leagues show that, like everything else, aqueous pro­duction slows down with aging.

PAUL HENKIND, MD, PHD

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