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Surgeons continue search for ideal glaucoma laser procedure
Selective laser trabeculoplasty and endoscopic cyclophotocoagulation show promise, but long-term data is lacking.
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The role of laser treatment in glaucoma management is in flux. New procedures with safety profiles seemingly better than those of older procedures have appeared, but widespread adoption of these techniques has not yet ensued. And overall laser use in glaucoma is decreasing, according to an analysis of Medicare data.
The supposedly less invasive procedures that have appeared in recent years, including selective laser trabeculoplasty and endoscopic cyclophotocoagulation, have their adherents, but long-term follow-up data is only beginning to appear. Whether they will see wider use as more data appears remains to be seen.
Meanwhile, use of argon laser trabeculoplasty, traditionally the second line in glaucoma treatment after maximum medical therapy, has declined steadily from a peak in the early 1990s.
Has the effectiveness of new glaucoma medications such as the prostaglandin-derived drugs reduced the need for ALT? Or have surgeons turned away from more destructive laser procedures but not yet found an ideal alternative among the less destructive procedures?
“We’re still looking for ‘the’ procedure of glaucoma surgery, kind of like the phaco of glaucoma,” said Mark Packer, MD, of Eugene, Ore.
In this article, Ocular Surgery News reviews some of the findings regarding the newer glaucoma laser procedures and explores the opinions of leading glaucoma specialists on the use of lasers in their subspecialty.
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ALT use declining
The traditional paradigm for glaucoma treatment has been medical management first, followed by ALT, followed by surgery. In end-stage cases, cyclodestructive procedures, including laser transscleral cyclophotocoagulation, may also be used.
But just as many surgeons have moved away from full-thickness trabeculoplasty and adopted the less invasive nonpenetrating glaucoma procedures, they are also searching for less invasive alternatives to the laser techniques.
There are drawbacks to the use of ALT, Dr. Packer noted.
“I gave up ALT 3 or 4 years ago when I made the transition to deep sclerectomy,” Dr. Packer said. “Prostaglandins were able to save eyes heading towards surgery. ALT seemed to return pressure or not lower it at all. And the scarring from ALT seemed to make patients not candidates for deep sclerectomy. The scarring would make it impossible to do dissection.”
Eve J. Higginbotham, MD, of the University of Maryland, noted that “Despite the benefits of laser surgery, the number of laser trabeculoplasties in the United States has declined in recent years. Between 1992 and 2000, there was a 57% reduction in the number of procedures performed in the United States.”
Dr. Higginbotham was referring to research by Chad D. Albright, MD, and colleagues at the University of Tennessee Health Science Center. Dr. Albright et al reviewed data from the Health Care Financing Administration (now the Centers for Medicare and Medicaid Services) from 1986 to 2000, the last year for which data was available at the time of their study.
The researchers found that laser trabeculoplasty use peaked in 1992 at 176,670 procedures and has declined since then. By 2000, only 76,838 ALT procedures were performed, according to the HCFA records.
Dr. Albright and colleagues concluded that possible explanations for the decrease in ALT use include physician perceptions of the clinical usefulness of ALT and the availability of alternative treatments.
“With the introduction of new antiglaucoma medications and improvements in surgical technique, ophthalmologists have other useful options besides [laser trabeculoplasty] in the treatment of glaucoma,” the authors said in their article, which appeared in Ophthalmic Surgery, Lasers and Imaging.
SLT data
SLT, invented by Mark Latina, MD, has shown promise as a safer version of ALT with similar clinical results. A Q-switched 532-nm laser, the Selecta II from Lumenis, is used to target only the pigmented cells in the trabecular meshwork, resulting in less tissue destruction than in the non-cell-specific ALT.
Long-term data on the procedure are beginning to appear. At last year’s International Glaucoma Symposium in Barcelona, Spain, Karim Damji, MD, discussed 3-year follow-up with the procedure.
Dr. Damji and colleagues at the University of Ottawa Eye Institute performed a study comparing ALT and SLT. Patients were randomized to receive one of the two laser treatments. The results showed that SLT achieved IOP-lowering results similar to ALT and was effective for up to 3 years.
The study focused on patients who were using maximum tolerated medical therapy, Dr. Damji said in an interview. Without SLT, most of the patients would have needed filtering surgery, he said.
But Dr. Damji acknowledged that while these data are promising, more are needed.
“We have the potential of repeating SLT, although that data has yet to come out. And a word of caution is needed until we have the equivalent of the Glaucoma Laser Trial for SLT – that is, an SLT vs. meds study that definitively shows SLT is effective in early glaucoma,” he said.
A multicenter clinical trial similar to what Dr. Damji describes, called the SLT/MED, is now enrolling patients. L. Jay Katz, MD, of Wills Eye Hospital, is coordinating the study. About 20 patients will be recruited at each of 15 sites across the continent.
More supporters, earlier use
Glaucoma surgeons are beginning to adopt SLT in growing numbers.
Dr. Higginbotham said the safety profile of SLT has been good enough for her to increase her use of laser trabeculoplasty.
“In the past year, I’ve probably tripled my numbers of trabeculoplasty,” Dr. Higginbotham said. “(SLT is) more gentle to the trabecular meshwork and has an attractive promise: It can be repeated. There’s some optimism, but because glaucoma is long term, it’s a cautious optimism.”
Dr. Higginbotham said use of SLT is bound to change as surgeons observe how patients fare with the therapy. She noted that surgeons and patients should have their expectations in check because, as with ALT, the effect of SLT will not last forever.
Dr. Higginbotham said that she does not always save SLT as a second-line therapy. She considers the cost of medications, side effects and patient compliance as factors in choosing SLT.
“At some point, they’re going to need medication. I don’t want people to think laser’s going to cure them,” she said. “I do think (SLT) should be high up in the armamentarium.”
Dr. Damji agreed that the place of SLT in the spectrum of glaucoma treatment is not yet clear.
“The question is, where do we position SLT?” said Dr. Damji. “Do we use it after trying a couple of medications or as first-line treatment? It seems like the effect does last for at least a couple of years in most patients.”
Dr. Damji said he has decreased his use of ALT and currently uses SLT as second-line therapy after medication has failed or as a first-line treatment in patients who may not comply with medications, can not afford meds or are intolerant to medications or the preservatives in medications.
The expense of a new laser may be a barrier to widespread adoption, at least for the present, several surgeons said.
“Data on SLT looks encouraging, especially if you’re not causing damage,” Dr. Packer said. “However, not all surgeons may be convinced that there is enough benefit to purchase a new laser.”
“I think there is a trend that people who can get an SLT machine will do it a lot earlier because it appears to cause minimal scarring,” said John Kung, MD, of Staten Island Ophthalmology in New York. SLT applies 0.01 of the energy used in ALT, he said.
Andrew Iwach, MD, of the University of California, San Francisco, said he believes SLT is viable for early treatment, and he suggested asking patients which treatment they prefer – more drugs or a minimally invasive laser procedure. Although glaucoma medications have improved, he said, some patients who fear side effects might prefer SLT.
“That’s where the option of laser therapy, such as SLT, is effective,” he said. “It’s not a perfect solution. It doesn’t work in everyone, and the effect may not last as long as desired. It at least offers a step that can be taken to reduce the risk without having the downside of medications.”
Dr. Iwach said SLT is appropriate for the most common presentations of glaucoma. He does not recommend using it on patients who have neovascular glaucoma or a history of inflammatory glaucoma.
Dr. Iwach said that at his hospital, which has lasers to perform both ALT and SLT, surgeons appear to prefer SLT to ALT when given a choice.
Excimer laser trabeculostomy shows promise in Europe |
Excimer laser trabeculostomy is a promising option for treating open-angle glaucoma. The procedure is increasing in clinical use in Europe, according to the procedure’s developer. In excimer laser trabeculostomy (ELT), an excimer laser is used to create holes in the inner wall of Schlemm’s canal without disturbing the outer wall and collector channels, said Michael S. Berlin, MD, who developed the concept more than 15 years ago. “ELT was developed … to treat the pathology of most open angle glaucoma at the anatomical site, connecting the anterior chamber to Schlemm’s canal, bypassing the obstructed juxtacanalicular tissue and the inner wall of Schlemm’s canal,” he said. ELT is a repeatable procedure that could serve not only as an alternative to trabeculectomy, but also as an alternative to selective laser trabeculoplasty. However, because ELT is invasive, it would more likely be used as a second-line therapy when SLT is inadequate or fails, Dr. Berlin said. “In ELT a 200-µm fiber optic probe is introduced through a paracentesis to contact the trabecular meshwork. It delivers nonthermal 308-nm Xe-Cl excimer energy to excise the juxtacanalicular trabecular meshwork and the inner wall of Schlemm’s canal without compromising the outer wall or the collector channels,” Dr. Berlin said. The result is an open passage that allows aqueous fluid to pass directly from the anterior chamber into Schlemm’s canal, bypassing the outflow obstructions characteristic of most open-angle glaucoma, Dr. Berlin said. ELT can be performed alone or in conjunction with cataract surgery. In combined surgery, ELT adds little time to the procedure and has proven even more successful in lowering IOP. This approach to lower IOP, decreasing outflow resistance, is more physiologic than procedures which decrease aqueous production, he said. The effect of ELT is estimated to last for 3 years, Dr. Berlin said. There is potential for aqueous reflux, but this has not been a major issue, he said. Dr. Berlin said ELT is showing promise in clinical practice in Europe, where other investigators independently developed the same concept and have advanced in clinical trials. A device for performing ELT is not currently available in the United States. For Your Information: |
ECP and cataract surgery
ECP is described as a less invasive alternative to the cyclodestructive procedures that used to be reserved for late treatment of refractory glaucoma. The procedure has been adopted by a number of cataract surgeons who find the device appealing because it allows them to visualize the structures being ablated and can be performed through the cataract incision.
So far ECP appears to be a safe way to ablate the ciliary body, surgeons interviewed for this article said. Hypotony, which was often a complication of older cyclodestructive procedures, has not been a problem, Dr. Kung said.
“We generally don’t use it alone early on simply because the fluid that’s produced in the ciliary body is nourishment for the eye … however, ECP’s ability to refine the area of treatment is in the same vein of SLT to minimize collateral damage. There are some who are starting to use it earlier in their treatment of glaucoma,” Dr. Iwach said.
ECP can be used to selectively ablate the ciliary body to reduce aqueous fluid production. A fiber optic carrying the laser and an endoscope is inserted into the eye, allowing visualization of the structures for ablation.
Dr. Kung said he sees ECP as most useful in conjunction with cataract surgery, not as a standalone procedure.
“I wouldn’t recommend doing it routinely as the sole procedure because the risk is too great to hit the lens and cause a cataract. Even if you inject a lot of viscoelastic, I don’t think that’s where the procedure would be ideally slotted. Ideally, it is used with phaco,” he said.
Like SLT, ECP is not for everyone, and surgeons continue to wait for long-term data. Although the effects of the therapy are not guaranteed to last, ECP may be enough to reduce or eliminate medications for a time, Dr. Kung said.
“Even if the pressure doesn’t drop enough to get a person off medication, there’s little risk and should definitely be considered,” Dr. Packer said.
“Until we have more long-term follow-up, we don’t know the ultimate benefit,” Dr. Iwach said. “In the shorter term, at least over a few years, many patients will have continued benefit.”
For Your Information:References:
- Karim F. Damji, MD, is an associate professor at the University of Ottawa Eye Institute. He can be reached at 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6; 613-737-8575; fax: 613-737-8836.
- Eve J. Higginbotham, MD, is chairwoman of the Department of Ophthalmology, University of Maryland School of Medicine in Baltimore. She can be reached at 419 W. Redwood, Suite 580, Baltimore, MD 21201; 410-328-5929; fax: 410-328-6346.
- Andrew G. Iwach, MD, can be reached at 490 Post St., Suite 608, San Francisco, CA 94102; 415-981-2020; fax: 415-981-2019.
- John S. Kung, MD, can be reached at Staten Island Ophthalmology, 3930 Richmond Ave., Staten Island, NY 10312; 718-948-8880; fax: 718-967-2757.
- Mark Packer, MD, can be reached at Drs. Fine, Hoffman & Packer Ophthalmologists, 1550 Oak St., Suite 5, Eugene, OR 97401; 541-678-2110 or 800-452-2040; fax: 541-484-3883.
- Albright CD, Schuman SG, Netland PA. Usage and cost of laser trabeculoplasty in the United. States. Ophthalmic Surg Lasers. July-August 2002;33(4):334-336.
- Higginbotham EJ. Reaffirming the role of the laser in glaucoma management. Arch Ophthalmol. August 1999; 117(8):1075-1076.