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Laser trabeculoplasty effective as initial glaucoma therapy
Laser procedures reduce pressure without the side effects of medications and filtration surgery, surgeon says.
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Laser trabeculoplasty as initial glaucoma therapy avoids complications caused by medications and filtration surgery, but can require repeat laser later, a glaucoma specialist said.
Speaking at Hawaiian Eye 2007, L. Jay Katz, MD, said physicians have been performing laser trabeculoplasty for more than 25 years and noted there is still confusion among surgeons about its uses. He said he uses it in a nontraditional role, as initial therapy, in certain patients instead of medications or filtration surgery.
“When you’re looking at laser trabeculoplasty — whether it is [argon laser trabeculoplasty] or [selective trabeculoplasty] — there seems to be a comparable IOP reduction when looking at lasers and medication as initial therapy,” he said. “But clearly, on the safety issues, compliance and cost, I think the laser certainly wins in those categories.”
Dr. Katz said laser as initial therapy will not be right for all patients. Each patient should be treated on a case-by-case basis, and all options should be explored before selecting one. Dr. Katz recommended that doctors offer newly diagnosed glaucoma patients the option of laser trabeculoplasty as a “reasonable” first-line treatment, instead of prescribing medications in a “knee-jerk response.”
Why initial treatment?
Dr. Katz said the standard glaucoma treatment paradigm has typically proceeded in the following order: maximal medical therapy, laser trabeculoplasty and filtering surgery. This paradigm is in transition with National Eye Institute studies, such as the Glaucoma Laser Trial, that have examined the use of ALT at the beginning of the treatment sequence or the more recent studies looking at SLT as initial therapy, he said.
He said the main reason to consider laser trabeculoplasty as initial treatment is because of the many complications posed by glaucoma medications and filtration surgery. Medications, although effective in many ways, also have ocular and systemic side effects, Dr. Katz said. Drug therapy may pose compliance issues with patients who do not take their medications for various reasons, including cost. Some patients may be nonresponsive to available medications. Tachyphylaxis, or long-term loss of efficacy, and peak/trough issues, concerning the variability of maintaining IOP over extended periods of time, are additional problems, Dr. Katz said.
“Finally, we have new concerns with some of the glaucoma medications that are coming to the forefront,” Dr. Katz said. “Maybe they’re cataractogenic – there’s been accelerated cataract development noted in trials comparing medical therapy with observation. [Benzalkonium chloride] surface toxicity on the conjunctiva may impair later filtration surgery, and there are some theoretical concerns that certain drugs may be impairing the circulation to the retina and the optic nerve.”
Filtering surgery can be associated with a number of intraoperative and postoperative complications and requires lengthy rehabilitation, Dr. Katz said.
In contrast, the main complication of laser trabeculoplasty is an IOP spike, he said. The IOP spike is usually transient, but is sometimes sustained, Dr. Katz said. The risk can be reduced with fewer shots, less energy and the use of alpha agonists in the perilaser period. Patients are at increased risk of spikes if they are on multiple medications, the procedure is a re-treatment, there is heavy trabecular meshwork pigmentation (eg pigmentary glaucoma) and the surgeon uses 360° treatment at one sitting instead of 180°, he said.
Study results
Many studies have been conducted looking at the repeatability and initial treatment possibilities of laser trabeculoplasty procedures, Dr. Katz said. One study, which was presented at the Association for Research and Vision in Ophthalmology meeting in 2005, examined 30 eyes. It found that by repeating the SLT as initial treatment 1 year after the first treatment, 80% of the time, there was a reasonable response with lowered IOP, he said.
Another study presented at ARVO in 2005 looked at patients who were treated with SLT, with at least 1-year follow-up. More than half of the eyes in the study, or 54%, had a successful response. About half, or 48%, of patients with repeat SLT had a good response, Dr. Katz said.
There have been a number of studies performed outside of the United States that examined SLT as primary therapy, Dr. Katz said.
“Uniformly, the nonrandomized studies have shown that SLT seems to lower pressure fairly well as a standalone procedure,” he said.
A prospective study by Shlomo Melamed, MD, and colleagues in Israel looked at 45 eyes of 31 patients who underwent SLT. Forty eyes had more than a 5-mm Hg drop in IOP with SLT, with an initial IOP of 25.5 mm Hg.
A nonrandomized prospective study in Canada looked at primary SLT as compared with a control group of latanoprost as initial therapy, Dr. Katz said. It showed there was a comparable drop between SLT and latanoprost. In the 74 eyes that had SLT, there was a drop in IOP of 8.3 mm Hg, or 31%. In the 26 eyes with latanoprost, the IOP drop was 7.7 mm Hg (31%).
The SLT/Medications Trial, a prospective study that randomly assigned patients but not eyes in the United States and Canada, took place at 17 sites, Dr. Katz said. The study compared SLT with topical medical therapy as initial therapy. Initial results show that patients had comparable baseline IOP reduction rates after at least 8 months of follow-up. Mesan IOP reduction in the medication group was 7.2 mm Hg, and in the SLT group it was 6.7 mm Hg, Dr. Katz said.
The long term benefit of SLT and the efficacy of repeat treatments remain unclear, but it remains a reasonable option for certain patients as initial therapy.
For more information:
- L. Jay Katz, MD, can be reached at Wills Eye Hospital Glaucoma Service, 900 Walnut St., Philadelphia, PA 19107; 215-928-3197; 215-928-3197; fax: 215-928-0166; e-mail: ljk22222@aol.com.
References:
- Lai J, Bournias, TE. Repeatability of selective laser trabeculoplasty (SLT). Presented at: Association for Research in Vision and Ophthalmology; May 1, 2005; Fort Lauderdale, Fla.
- McIlraith I, Strasfeld M, Colev G, Hutnik CM. Selective laser trabeculoplasty as initial and adjunctive treatment for open-angle glaucoma. J Glaucoma. 2006;15(2):124-130.
- Melamed S, Ben Simon GJ, Levkovitch-Verbin H. Selective laser trabeculoplasty as primary treatment for open-angle glaucoma: a prospective, nonrandomized pilot study. Arch Ophth. 2003;121:957-960.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.