Laser versus Drops

W hen it comes to laser trabeculectomy versus drops for the treatment of glaucoma, both can be effective for lowering intraocular pressure (IOP), but neither is perfect. Some of the downsides to laser include a need for retreatments over time, and possible damage to the trabecular meshwork. And while drops can have their downside, the newer ones show greater effectiveness and fewer side effects than older ones, according to Anton Hommer MD, from the Medical University of Vienna, Austria. He spoke at the 5th World Glaucoma Congress where he reviewed the evidence for both forms of treatment.

In short, laser won't be replacing drops, though there is certainly an important role for it, he said. Laser trabeculectomy is attractive because it tends to lower IOP between 20 to 30 per cent from baseline. However, there is about a 10 per cent loss of efficacy over a year, meaning at least 50 per cent of patients are not well-controlled after five years, he said.

First-line option

The Glaucoma Laser Trial from 1990 compared argon laser (ALT) to beta-blocker drops, and determined that laser was safe and could be considered as a first-line option. However, some evidence in the literature shows ALT (especially with repeat treatments) can destroy the trabecular meshwork, and slowly loses efficacy over the long-term, Dr Hommer said. Since then, medications have improved. There are better combinations, preservative-free versions and improved tolerability. The downside is that these too can lose efficacy over time, with only about 60 per cent of patients having continued lower IOP after two years of treatment.

He noted that prostaglandins seem to fare better than other medications. As for select laser trabeculoplasty (SLT), the IOP-lowering effect is similar to that of ALT, plus, again, patients likely need to be retreated – defined as using the laser on the same area of the eye. One study investigated the long- term IOP-lowering effects of doing 360-degree SLT treatment. After the first laser treatment, after two years there was efficacy in only 36 per cent of the patients. Efficacy was less after the second treatment, and after a third treatment, the numbers of patients getting a strong IOP- lowering effect gets very weak, Dr Hommer reported.

Less damage

Overall, SLT is about as effective as ALT, but has the advantage of offering less damage to the trabecular meshwork. "But the retreatment is not any more effective than ALT," Dr Hommer said. There is some variation in terms of what guidelines recommend, but they lean towards using drops first. One, UK's NICE Guidelines "don’t even mention the laser treatments," for ocular hypertension or glaucoma, he noted. “Still, laser trabeculoplasty is a good option for some patients. In my mind, there is no real superiority concerning efficacy or tolerability of SLT versus ALT – and I use both. And it is a reasonable option in patients who have difficulties taking the drops. On the other side, a potential disadvantage of laser trabeculoplasty is that the patient is not reminded every day – like with the drops – that he has a disease," he said.