Could modern surgery become a primary option in glaucoma treatment?

Nonpenetrating may be a viable option

Keith Barton

With the deluge of new glaucoma drugs that have appeared in the past 14 years, medications have supplanted surgery as the first-line treatment for all primary open-angle glaucoma sufferers. Medical therapy is perceived to be safer, despite evidence that compliance is poor, that many patients with ocular surface disease have a low tolerance of topical treatment and that medical treatment is significantly less effective than surgery.

Surgical management has been relegated somewhat inappropriately to the status of treatment of last resort and mainly reserved to patients with secondary glaucoma. Yet many patients with primary glaucoma would be better served with early surgery, also considering that the surgical options have changed and improved significantly over the past 10 years.

There is ample evidence from randomized clinical trials that a trabeculectomy performed early in the course of glaucoma has a greater chance of long-term success in terms of IOP control than one performed after years of medications. Understandably, surgeons have suggested caution in adopting it as a first-line therapy because of the potential disadvantages of filtration surgery.

However, primary surgery does not necessarily mean trabeculectomy. Both nonpenetrating surgery and aqueous shunts, with their higher safety profile and progressive technical improvements, should not be judged as unnecessary if they can avoid years of drops — even if the pressure could have been controlled medically. Although nonpenetrating surgery seems to be less effective in terms of IOP-lowering than trabeculectomy, nonpenetrating surgery with collagen implant, mitomycin C and goniopuncture has narrowed the gap and may compare favorably with medication, not only in terms of safety and tolerability, but possibly also in cost-effectiveness and efficacy.

I believe that for many patients with relatively mild glaucoma, early nonpenetrating surgery might be a safe and relatively effective primary therapeutic alternative to the lifelong burden of eye drops.On the other hand, nonpenetrating surgery may be less appropriate than trabeculectomy with MMC for the control of patients with advanced glaucoma who require a more aggressive surgical treatment. The results of the Tube Versus Trabeculectomy Study will likely show that aqueous shunts might produce similar outcomes in these patients without the risk of bleb-related infection that is associated with limbal aqueous drainage, thereby offering a further effective alternative to medical therapy.

In summary, it is important to differentiate patients presenting with advanced glaucoma and patients with milder disease when considering primary surgical therapy. Although primary surgery is probably under-utilized in both groups, the former group is most likely to suffer vision loss as a result.

Keith Barton, MD, FRCP, FRCS, FRCOphth, is a Consultant Ophthalmologist, Moorfields Eye Hospital, London.

Surgery should still be avoided

Anton Hommer

Glaucoma medical therapy has improved tremendously over the past 10 to 15 years. We can now rely on better and more powerful topical drugs, more effective in lowering IOP with significantly fewer side effects. In many cases, a single agent in a daily dose is sufficient to provide stable and long-lasting IOP control.

The improved quality and safety of medical therapy has determined a considerable decrease in the number of surgical procedures performed to treat glaucoma. Many studies have documented a downward trend for trabeculectomy by 30% to 50%, and I regard this as a great achievement.

Whenever possible, surgery should be avoided, or at least postponed as much as we can. Certainly it should be the last, and not the first, resort because, even in the best hands, it is always a risk. If you can obtain the results you want with medications, this risk should be avoided.

Nonpenetrating surgical procedures, including the latest developments of mini-shunts, may have a higher safety profile than trabeculectomy but are less effective in terms of IOP lowering than a good medical regimen.

In addition, for a variety of reasons, the long-term success of all surgical options is limited, and most patients end up having to take medications as well after a few years if not from the start.

Primary surgery is indicated only in a few cases of advanced glaucoma or when socioeconomic conditions and the absence of health care facilities prevent a regular follow-up of the patient and a regular supply and administration of drugs. In these cases, surgery as a first-line therapy makes sense, but we hardly find ourselves dealing with such conditions in our developed countries.

In all the guidelines on glaucoma therapy, here in Europe as in the U.S. but also in Japan and in Southeast Asia to just mention a few, medications are indicated as first choice.

We can rely, as I said, on a variety of IOP-lowering agents, including prostaglandin analogues, beta-blockers, carbonic anhydrase inhibitors and alpha agonists. We can use them as monotherapy or, whenever monotherapy doesn’t work, in different fixed and unfixed combinations. Fixed combinations are becoming popular, as they reduce the number of drops instilled per day, improving patient compliance. With such an armamentarium of different options, it is sensible to at least try medical therapy first.

Some may argue that on eyes in which medications have been used for several years, surgery if needed at a later stage is more likely to fail. This is true in some cases and is mostly due to the preservatives rather than to the agents themselves. On the other hand, in the majority of patients, this problem will never occur because medications will make surgery unnecessary.

Anton Hommer, MD, is a Senior Consultant at the Hera Hospital, Vienna.