Putting SLT Into Practice
It's not a perfect procedure -- but its
advantages are formidable.
BY M. CATHLEEN SCHANZER, M.D.
As a general ophthalmologist, it's not always easy to know when to introduce new technology into a practice. However, our practice has a huge glaucoma population, so issues of compliance, the cost of medications and the side-effects of those medications are all important concerns. Laser surgery was an option I felt we needed to consider.
Argon laser trabeculoplasty (ALT) has been used to treat glaucoma for many years, but because of the collateral damage it causes to the trabecular meshwork it has limited reusability. However, I found that selective laser trabeculoplasty (SLT) was a viable alternative to ALT, with several potential advantages. Initial studies of SLT had produced about 4 years of data, which indicated that SLT causes a 20% to 30% drop in IOP, similar to ALT. But unlike ALT, SLT doesn't produce collateral damage. As a result, it can be done multiple times -- even after ALT has failed.
SLT clearly could be an important option for our pa-tients. So, we decided to add SLT to our practice offerings.
What we found
SLT has turned out to be very worthwhile for both our patients and our practice. In addition to being non-destructive, we've found that:
- SLT has a low complication rate.
- SLT is patient-friendly; it's quick, and patients find it much more comfortable than ALT.
- SLT can be protective in situations where there may be a compliance issue. Because we're lowering IOP, even if a patient fails to use a prescribed medication, the spike in IOP is not as high as it might have been.
- The procedure is easy to perform.
- It can be used repeatedly, if necessary.
- SLT is a good alternative for patients who have tried ALT but need further treatment.
- To our surprise, we found ourselves receiving referrals from other M.D.'s in the area because we were the first to offer SLT. Receiving referrals from both M.D.s and O.D.s has had a significant impact on the growth of our practice.
Performing the Procedure
Before surgery I place Alphagan and Pred Forte in the operative eye. This is followed by Ophthaine, then I insert the Goldmann 3 mirror lens.
The laser used to perform SLT is a frequency-doubled, Q-switched Nd: YAG laser that produces a wavelength of 532 nanometers. Treatment is accomplished in single-burst mode using a spot size of 400 microns with a duration of 3 nanoseconds per spot. (The 400-micron spot is large enough to cover the entire height of the trabecular meshwork.) I place about 50 spots, touching but not overlapping, across 180° of the trabecular meshwork.
To determine the most effective energy level for treatment, I use the lowest energy level that produces a small puff of pigment or causes bubble formation, and then lower that level slightly. The correct level is usually around .6 to .8 millijoules, but may vary according to the amount of pigment in the trabecular meshwork.
One hour after treatment I check the IOP because the pigment release can cause an IOP spike. I then instruct the patient to use Pred Forte q.i.d. and return in 1 week.
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Data from retrospective study of SLT patients treated
at Southern Eye Associates, PC, in Memphis, Tenn. |
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Checking Outcomes
To determine how effective treatment with SLT has been, we divided the treated patients into groups, depending on their circumstances before receiving treatment. Of the last 135 SLT patients we treated:
- 84 were already using the maximum level of medications they could tolerate
- 19 were using a single medication
- 28 had either failed to respond to ALT, or it was no longer effective
- 4 underwent SLT as their primary treatment.
We evaluated SLT's effect on IOP, as well as any adverse effects. (Note: We omitted two groups of patients from the analysis. First, we didn't include patients who had anterior chamber inflammation, pain or redness preoperatively -- and still had it postoperatively -- because we wanted to evaluate events precipitated by SLT alone, without the influence of other factors. We also omitted patients whose IOPs only changed 1 or 2 mm Hg, in order to exclude results that might have been attributable to differences in individual physician technique, or the use of different tonometers.)
► A small percentage of patients who had "failed" ALT or were on maximally tolerated medications (an indication of "sicker" eyes) showed adverse symptoms. In contrast, those who underwent SLT as their primary therapy, or who were just starting medications, experienced no adverse events. (See "Adverse Events Following SLT".)*
► The total drop in mean IOP of all patients over time was 22%, but patients who underwent SLT as their primary therapy or who were on minimal meds for a shorter period of time showed the greatest drop in IOP. (See table*, below.)
Note: Because our practice often receives referrals from optometrists, many of our patients have been on medications for some time before coming to us. As a result, the number of patients in our practice receiving SLT as a primary treatment, plus those who were only using one medication, was small -- only 23 patients. Nevertheless, the data clearly suggest that the earlier patients are treated, the better their response to SLT.
Managing the Bottom Line
From a revenue standpoint, SLT is reimbursed at the same rate as ALT, and billed using the same codes. At our practice, performing six or seven SLT procedures per month pays for the laser. (Of course, the number of procedures required to cover costs will depend on the individual lease agreement.)
Although it's distasteful to look at the practice of medicine from a business standpoint, in today's economic climate, every penny counts. In this area, SLT is advantageous. Prescribing medication may be efficacious, but it's not profitable. The laser, however, does create the potential for profit, including the fact that it can be repeated when necessary.
A Procedure with Potential
SLT has changed our way of managing glaucoma; we're now trying to perform the procedure earlier. Because there's no thermal or collateral damage, SLT won't affect the success of future surgical procedures. At the very least, it can delay the need for additional medications or incisional surgery.
Ultimately, SLT could become our first-line treatment for open angle glaucoma.
Dr. Schanzer practices at Southern Eye Associates, PC, in Memphis, Tenn.
*All chart data from retrospective study of SLT patients treated at Southern Eye Associates, PC, in Memphis, Tenn.
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SLT: Changing Priorities |
Danny Luong, M.D., a general ophthalmologist practicing in San Jose, Calif., has offered SLT to his patients since January 2002. "A lot of my patients weren't happy about having to use eyedrops every day. They complained about discomfort, and compliance was a problem. In contrast, SLT provides good IOP control and I don't have to worry about compliance. "The results of SLT treatment have been impressive. I'm able to get most patients who were using one medication off medication altogether. Most patients who were using two meds end up only having to use one. And the effect lasts; after a year and a half about 60% of the patients I've treated still have their IOP under control and don't need retreatment. About 30% have shown a slight rise in IOP, so I've retreated those patients. Only about 10% didn't respond to SLT at all. "In the beginning I only offered SLT to patients whose IOPs weren't controlled by medication. However, the results have been so good that I now offer the laser as the first option when patients come in with ocular hypertension or primary open-angle glaucoma. THE PATIENT PERSPECTIVE "When I discuss treatment options with a new patient, I talk about the medication alternatives -- including their side-effects -- and I explain that, like medications, SLT won't work for every patient. In spite of that, most patients choose the laser. Of course, patients are happy if their IOP drops. But even if it doesn't, patients aren't upset. There's no sacrifice involved --the treatment is totally painless and there are no side-effects. "The majority of patients -- who do respond to SLT -- have other reasons to be happy. Most patients using eyedrops spend $20 to $30 every month in insurance co-pays; that adds up to $300 or more a year. With the laser they don't have to deal with the eyedrops or their side-effects, and they save all that money. Patients without insurance save thousands of dollars." PERFORMING SLT Dr. Luong says the procedure takes him less than 30 seconds -- at most 1 minute per eye. "I start with the power set around .8 millijoules, and I treat the inferior 180°, doing 50 spots next to each other. The endpoint I'm looking for is tiny bubbles in the aqueous in front of the trabecular meshwork. If I see physical changes in the tissue, I know the energy's set too high. "If a patient comes back for a repeat treatment, I do the superior 180°. "Performing SLT is much easier than ALT. In ALT you have to focus on a specific area with a very narrow beam, and if the patient's eyes move it's hard to hit the right spot. With SLT the patient can move a little bit and it really doesn't matter." PRACTICE IMPACT "Offering SLT has brought in a lot of new patients, most of whom are referred by other patients. I haven't publicized the fact that I have the laser -- my patients do my advertising for me! Patients come from 50 to 60 miles away to have SLT done. "I recouped the cost of purchasing the laser in about 6 months. I didn't use financing. Given my volume of glaucoma patients, it made more sense for me to buy it outright. "To the best of my knowledge, all insurance coverage reimburses for this treatment. I haven't had any denials." A NEW SET OF TREATMENT PRIORITIES Dr. Luong says that SLT has changed the way he thinks about glaucoma treatment. "Before SLT, our regimen was eyedrops, followed by laser, followed by surgery. Now it's laser, followed by eyedrops and then surgery. "In fact," he adds, "offering SLT has decreased the number of patients who require surgery. That's an additional cost saving for the insurance companies, too."
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