Medication likely to remain first-line glaucoma therapy in near future, experts say

However, advances in surgical and laser procedures and the current economic climate may alter some patients’ treatment choices.

Steven J. Gedde

While recent glaucoma surgical and laser innovations have shown promising adequate pressure lowering and safety profiles, medication continues to be first-line therapy for primary open-angle glaucoma patients.

However, the future of glaucoma treatment might depend on economic factors, some experts say. In addition, while progress has been made in surgical management in recent years, the latest innovation in medical therapy agents was more than a decade ago, with the introduction of prostaglandins.

New medical innovations could be on the horizon as researchers make inroads in improving the safety and efficacy of alternatives to trabeculectomy.

“I think there’s a good possibility that if we develop an operation that is highly successful and has low rates of complications associated with it, that may alter our current paradigm and direct us toward initial surgical treatment for glaucoma,” Steven J. Gedde, MD, an OSN Glaucoma Section Member, said.

Rationale for current paradigm

There are many reasons for the current medical paradigm, the foremost being that medical therapy is safe and effective, Dr. Gedde said. After prostaglandins replaced beta-blockers as first-line glaucoma treatment with the introduction of Xalatan (latanoprost, Pfizer) 12 years ago, the drug and others in its class became the most prescribed glaucoma medications.

The other glaucoma drugs in the prostaglandin family are Travatan (travoprost ophthalmologic solution 0.004%, Alcon), Travatan Z (travoprost 0.004%, Alcon) and Lumigan (bimatoprost ophthalmic solution 0.03%, Allergan).

“Once prostaglandins were introduced, they rapidly became the first class of glaucoma medications because of their efficacy and safety and daily dosing,” Dr. Gedde said. “I think prostaglandins, when they were introduced, instantaneously became an important class. I think they continue to be an important class of glaucoma medications.”

In addition, 5-year results from the Collaborative Initial Glaucoma Treatment Study, which randomized patients with newly diagnosed glaucoma to initial medical therapy or trabeculectomy, supported medical therapy as initial treatment without a change to the current medical treatment algorithm, Dr. Gedde said.

Douglas J. Rhee

The two combination drugs on the U.S. market, Combigan (brimonidine tartrate, timolol maleate ophthalmic solution, Allergan) and Cosopt (dorzolamide HCl, timolol maleate ophthalmic solution, Merck), address compliance, one of the most common issues with drug therapy, according to Douglas J. Rhee, MD, an OSN Glaucoma Section Member.

He said studies have shown that increasing the number of drops can lead to reduced compliance, so an option of fewer medications has assisted in maintaining the medical therapy paradigm.

Dr. Rhee said another reason for the current paradigm is patient choice and the culture of medical practice in this country. Many patients in the United States view drug therapy as initial first-line treatment and choose it before surgery. Laser trabeculoplasty has been shown to have good pressure lowering results with limited complications, but patients still tend to opt for drug therapy first, Dr. Rhee said.

“I think patients have an expectation for a health condition, whether it is for glaucoma or any other condition, the initial treatment is with medications. It’s rare for people to think of surgery, except for traumatic conditions,” he said.

Future of glaucoma treatment

If any one factor alters glaucoma therapy in the immediate future, it could be the recent economic downturn, Dr. Rhee said. Economic issues could possibly alter treatment if patients deem surgery to be less expensive than chronic medication use and therefore a more attractive treatment option.

Continued research into new devices and procedures, such as the Trabectome (NeoMedix), Solx gold shunt and canaloplasty (iScience Interventional), could affect the future treatment paradigm, as physicians discover new and improved ways to perform glaucoma surgery, Dr. Gedde said.

“There’s even evidence to suggest that some older procedures, like tube shunts, may be good surgical alternatives to trabeculectomy,” he said. “I’m not sure whether we have found the best glaucoma procedure yet, but we need well-designed studies to evaluate these new surgical procedures before we can commit to them.”

Innovations in glaucoma drug therapy might also be available in the future, as researchers investigate new compounds, Dr. Rhee said.

A possibility is Rho-kinase inhibitors, which have been shown to safely lower IOP. Dr. Rhee cited a study by Tanihara and colleagues that examined results of a selective Rho-associated coiled coil-forming protein kinase inhibitor, SNJ-1656, 0.003% to 0.1%, in 45 patients. The randomized, double-masked, group-comparison, phase 1 clinical trial found that the agent was safe, with significant IOP reductions after repeated instillations.

Dr. Gedde said a new class of agents might improve treatment algorithms by expanding available options. “Hopefully we’ll see some new medications and some new drug delivery systems allowing medications to be delivered in a slow-release form,” he said. “Interesting work is being done in these areas as well.” – by Erin L. Boyle

Reference:

• Tanihara H, Inatani M, Honjo M, Tokushige H, Azuma J, Araie M. Intraocular pressure-lowering effects and safety of topical administration of a selective ROCK inhibitor, SNJ-1656, in healthy volunteers. Arch Ophthalmol. 2008;126(3):309-315.

• Steven J. Gedde, MD, can be reached at Bascom Palmer Eye Institute, 900 NW17th St., Miami, FL 33136; 305-326-6435; fax: 305-326-6474; e-mail: sgedde@med.miami.edu.
• Douglas J. Rhee, MD, can be reached at the Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02144; 617-573-3670; fax: 617-573-3707; e-mail: dougrhee@aol.com.