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Glaucoma regimens must be tailored to the patient
Benefits of aggressive treatments must be balanced against the risk of side effects.
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STANFORD, U.S.A. – Attempting aggressive maximum IOP lowering to treat glaucoma has become a recent trend. However, according to Kuldev Singh, MD, MPH, an associate professor of ophthalmology at the Stanford University Medical Center, many patients with mild optic nerve damage or ocular hypertension without field loss do not need to achieve IOPs below 12 mm Hg or even in the low teens.
Most patients in developed countries who carry the diagnosis of glaucoma do not go blind from the disease, according to Dr. Singh. Many will not even note any visual symptoms during their lifetime.
It is impossible to prospectively know how low any patient’s IOP should be, Dr. Singh said. The traditional guideline of lowering IOP to less than 21 mm Hg was an oversimplified goal, and it is just as wrong to select goals such as 18 mm Hg, or to 12 mm Hg for all patients. Trying to achieve these low levels may run the risk of increasing treatment-related side effects.
“Each glaucoma patient is unique,” he told Ocular Surgery News. “To treat patients with varying degrees of disease severity with the same therapeutic goals doesn’t make much sense. The more severe the disease, the more side effects you’re willing to tolerate to get maximal effect of the treatment. If you are dealing with a patient with mild disease, the side effects may end up worse than the disease.”
Dr. Singh said a tradeoff exists between efficacy and tolerability with drugs and surgery. He spoke at the International Congress of Ophthalmology meeting in Sydney, Australia, about “Medical Therapy for Glaucoma: Balancing Efficacy, Safety and Tolerability.”
Tradeoffs exist
Tradeoffs are often made between safety and efficacy. For instance, in glaucoma surgery, anti-fibrotic drugs such as mitomycin-C improve the success rate of trabeculectomy. But the downside is that sometimes the use of such drugs are associated with greater rates of complications.
Within a class of drugs, a tradeoff between efficacy and safety is common. More effective agents are also more likely to have side effects. Beta-blockers as a class demonstrate this tradeoff. Timolol is more effective than betaxolol, but betaxolol is an overall safer beta-blocker because it has fewer respiratory side effects, Dr. Singh said. In the 1980s, in patients for whom safety was the primary concern, betaxolol was often used. In patients for whom efficacy was relatively more important, timolol was the preferred agent.
This tradeoff can be expressed as the therapeutic index that reflects the balance of efficacy, tolerability and safety.
“The greatest advances in medicine occur when you improve the therapeutic index. We have seen this with the development of the prostaglandins, as they are both safer and more effective than the beta-blockers,” Dr. Singh said.
Treating glaucoma patients is not just about IOP.
“It’s also about safety and tolerability, especially in patients who have relatively mild forms of the disease,” he added.
Letting patients choose
Dr. Singh concluded that medical and surgical regimens must be tailored to the patient.
“When comparing equally effective drugs, a good physician will discuss the side effects, and will make the decision based on the side effects that are most acceptable to the patient. That’s a decision that the physician can’t always make for the patient,” he said.
For Your Information:
- Kuldev Singh, MD, MPH, can be reached at Stanford University Department of Ophthalmology, Blake Wilbur W3002, Stanford, CA 94305-5353 U.S.A.; +(1) 650-723-5517; fax: +(1) 650-723-7918; e-mail: kuldev.singh@forsythe.stanford.edu.