As you know, the critical factor in managing glaucoma in most patients is controlling intraocular pressure (IOP). When IOP remains high for an extended period, damage to the optic nerve is inevitable. We are therefore in a race against time as we try to find the best treatment regimen for our patients.

Most doctors use medications to keep IOP from exceeding acceptable limits. Unfortunately, medications can cause systemic side effects -- and they don't always work.

Laser trabeculoplasty (LTP) is a worthy alternative. It can provide many benefits to the patient, especially if you're postponing or trying to avoid invasive filtration surgery.

Clinical evidence

The Glaucoma Laser Treatment Trial, conducted by the National Eye Institute in the 1980s, demonstrated some of the concrete benefits of LTP. Patients were randomly assigned glaucoma management using medications or LTP. Of those patients who received LTP, 75% did eventually need medication. (Treatment with LTP shows an average annual loss of efficacy of 10% per year.) However, 25% of these patients did not need medication; their IOPs were controlled by LTP alone.

In another NEI-supported clinical trial, the Advanced Glaucoma Intervention Study, patients with advanced glaucoma were randomized to receive either laser trabeculoplasty followed by trabeculectomy, or the reverse. African American patients maintained their level of control more effectively when they underwent laser trabeculoplasty before filtration surgery. (Caucasian patients did slightly better with filtration surgery first.) Clearly, for many patients, laser trabeculoplasty is an important intervention to consider.

Usage today

The American Society of Cataract and Refractive Surgery (ASCRS) recently surveyed 947 practicing ophthalmologist members to find out how they were applying the currently available treatments for glaucoma.

About half of the respondents reported that 10% or more of their patients were African American -- at increased risk for developing glaucoma. Despite this fact, the survey found that the majority of responding doctors only perform six to 20 laser trabeculoplasties per year.

The implication is that many of our colleagues rely heavily on medication to control IOP in glaucoma patients. Indeed, the ASCRS survey found that 70% of ophthalmologists wait until maximal topical therapy (three or four eyedrops) has failed before resorting to LTP. I believe these numbers indicate that LTP is greatly underutilized.

Ironically, when asked at what point in the therapeutic sequence ophthalmologists would want LTP for themselves, 28% said they would have LTP after only one or two medications proved inadequate. Sixteen percent responded that they would prefer LTP as an initial treatment.

The longer it takes to find an adequate medication, the greater the chance of optic nerve damage. I believe LTP should be considered as an early intervention in IOP management.

Overcoming barriers

The impact of LTP in successfully managing IOP has been demonstrated. Given that fact, why are so many of us hesitant to use it more aggressively?

I believe there are three main reasons LTP is underutilized:

�         Loss of efficacy over time. It's true that LTP treatment loses efficacy over time. Yet the Glaucoma Laser Treatment Trial clearly demonstrated that 25% of our patients can avoid medication entirely after treatment with LTP. This is a tremendous benefit. Even if efficacy is lost over time, LTP can prevent damage to the optic nerve during a critical period.

�         Access to a laser. Many ophthalmologists don't own a laser; 23% of ASCRS survey respondents rely on a hospital for access to a laser. Given the potential benefits of LTP, it's important to consider strategies to improve your access to a laser.

�         Concerns about complications or pressure spikes following the procedure. According to the ASCRS survey, most surgeons seldom see pressure spikes greater than 10 mm Hg following LTP. (79% of survey respondents reported seeing this in less than 5% of their procedures.)
Proactive measures help to minimize this problem. Most practitioners now pretreat with medications to prevent a pressure spike. (Alpha-2 agonists and topical carbonic anhydrase inhibitors are effective for lowering IOP acutely.) Also, following the patient carefully during the hours after the procedure greatly reduces the risk of missing a sustained elevation in IOP.

How I use LTP

I've adopted LTP in my practice with great success. I now apply LTP after only one or two medications have failed to treat IOP adequately.

I sometimes even use LTP as a first-line therapy when patients are at risk for aggressive progression of glaucoma. A recent study conducted at the University of Illinois noted that patients who progress more aggressively also have greater variations in their IOP. Applying LTP for these patients provides security by preventing permanent damage to the optic nerve.

However, LTP isn't for every patient. I avoid using LTP when a patient has severe glaucoma or more than 6 hours of closure of angle due to peripheral anterior synechiae (PAS). I also use topical steroids to avoid postoperative inflammation. (This is particularly important in patients with darkly pigmented irides because these patients often develop PAS.)

A valuable resource

LTP is an excellent tool that we should consider implementing more often and earlier in the treatment of glaucoma. When medications fail, or it takes too long to find the correct medication, LTP can help prevent damage to the optic nerve. Indeed, LTP can help some patients avoid medications altogether, and can postpone or avoid invasive filtration surgery.

I urge you to consider taking more advantage of this valuable resource in your practice.

Dr. Higginbotham chairs the Department of Ophthalmology at the University of Maryland School of Medicine in Baltimore.