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Initial treatment options
 Robert J. Noecker, MD, MBA |
Ophthalmologists who treat patients with glaucoma need to take into consideration future treatment steps. It is worth the time and effort to find a medication or combination of medications that will guarantee the most success for the patient now and in the future.
When an ophthalmologist initially treats a patient with glaucoma, the goal is to achieve the lowest intraocular pressure (IOP) possible with monotherapy. The medication should have good efficacy, be consistent in response rate and be predictable. Ophthalmologists want to achieve consistent IOP lowering. There is a significant risk factor for fluctuations in IOP in some patients, and issues of adherence to and compliance with the treatment regimen abound.
Ophthalmologists have different options for treating glaucoma. For individual drugs, prostaglandin analogues and beta blockers are medications that can achieve a 20% IOP drop that is a common goal for primary therapy.1
Prostaglandin analogues are the dominant class of glaucoma therapy. The relative efficacy of these drugs is a few millimeters of mercury lower IOP in study populations compared to the former gold standard of beta blockers. There are other options for achieving low IOP, including high doses of medication or procedures such as selective laser trabeculoplasty. However, high-dose medication can have side effects, and a majority of patients choose medical therapy over a surgical procedure as the first choice in glaucoma treatment.
Compliance
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Monotherapy is a simple first step for IOP management. Patients will show better compliance when prescribed one drop once a day rather than a complex regimen with various dosing patterns throughout the day. If monotherapy does not achieve proper IOP lowering, then adjunctive agents need to be considered to enhance therapy.
A study conducted by Alan Robin, MD, showed the effect of creating a more complex treatment regimen compared to one drop a day therapy.2 The study reviewed refill rates at the pharmacy level when adding a second medication. The study showed that 25% of the time patients do not adhere to the proper dosing schedule. This can be due to a variety of reasons, including problems with refills, patients alternating drugs or using the first medication less. Adding complexity to the treatment regimen can result in less than optimal usage of the medications.
Switching medications
In the past, if initial therapy did not achieve the IOP lowering goals, then ophthalmologists would add medications to the initial therapy. Today a number of new medication classes are available, and switching from one monotherapy to another is the route most ophthalmologists take. Switching medications decreases side effects and keeps compliance issues to a minimum.
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There are enough individual differences between prostaglandin analogues that switching a patient from one medication to another could provide adequate IOP reduction. A study conducted by Stefano A. Gandolfi, MD, looked at nonresponders to initial glaucoma therapy and whether ophthalmologists should abandon a class of medication when it shows no response or if another similar agent should be used.3 In the study, initial therapy was latanoprost. When patients did not show improvement over baseline, latanoprost was prescribed again. If there still was no response, patients were switched to bimatoprost. The study showed that the switch to bimatoprost provided a significant reduction in IOP. The study population was small and select, but there appears to be enough difference that it is a worthwhile endeavor to try to switch within drug class. While controversial, switching is considered appropriate by a majority of doctors.
It is critical that monotherapy as initial medication provide 20% to 25% reduction in IOP. Despite advances in current monotherapy medications, however, patients do not all respond to medication the same way. The result is that a significant number of patients require additional therapy.
References
- American Academy of Ophthalmology. Primary Open-Angle Glaucoma, Preferred Practice Pattern. San Francisco: American Academy of Ophthalmology, 2005. Available at: www.aao.org/ppp.
- Robin AL, Covert D. Does adjunctive glaucoma therapy affect adherence to the initial primary therapy? Ophthalmology. 2005;112:863-868.
- Gandolfi SA, Cimino L. Effect of bimatoprost on patients with primary open-angle glaucoma or ocular hypertension who are nonresponders to latanoprost. Ophthalmology. 2003;110:609-614.