Mr. Tin Aung: Hi. Good afternoon, everyone. I'd like to welcome you to my talk on the efficacy of SLT for angle closure glaucoma. So, I've received research support as well as travel support from Ellex before

So, as you know, in Glaucoma, there's two main forms of Glaucoma, open angle and closed angle glaucoma. And angle closure glaucoma is an important cause of glaucoma worldwide, especially in Asia. It affects more than 13 million people. It's also a form of glaucoma that causes a lot of blindness in the world

The conventional management of angle closure glaucoma involves doing a laser iridotomy as the first line of treatment. This is the reason why we do a laser iridotomy is to relieve the pupil block that's present in the condition

As you can see in this picture, a patient with angle closure with pupil block knocked [sp] by a convex iris configuration. And after the laser iridotomy, the iris is flatter, and you can see the angle has opened up

However, we know that if we do a laser iridtotomy for patients with chronic angle closure glaucoma, many patients require further medical treatment. For example, they may require--90 percent may require medical treatment, and 50 percent may require surgery

So, what about SLT for angle closure glaucoma? We know that SLT is a safe and effective treatment for open angle glaucoma because it targets the pigmented cells in the trabecular measure who have no collateral damage to the underlying structure

And SLT may also be a treatment option for angle closure patients in whom the angle has widened following laser iridotomy so that you can see the trabecular measure to apply the SLT shots

Here's an example of a patient of angle closure glaucoma. As you can see in the picture on the left, he has no angle structures visible. However, after laser iridotomy, you can see that some angle structures become visible. And this, you can see the trabecular measure within this picture, and this is where you can perform SLT in the part of the angle which is open

So, back in 2009, a multi center study was performed for SLT for angle closure glaucoma. There were four countries involved in the study, and it looked at 65 patients or 65 eyes. Every patient had post laser iridotomy for at least one month and high pressure after the iridotomy

In every patient, the trabecular measure must be visible for at least 90 degrees, and they treated an extent of about--a mean of 170 degrees with a mean of 56 shots. And this--the medications were kept the same throughout the study

So, this preliminary study, they found that SLT could reduce the IOP from a mean of 24 to a mean of 19 degrees mercury after six months. And this was quite a significant drop in IOP, although the medications remained the same

Based on this data, in Singapore, we performed a new randomized perspective controlled trial comparing SLT versus prostaglandin analogs, in this case Travatan. We also recruited two other centers from Jakarta and Hong Kong

So, the aim of the study was to determine if SLT is an effective treatment for lowering IOP in patients with chronic angle closure over six months. So, we recruited patients who had angle closure of at least 180 degrees before the laser iridotomy. But, after the laser iridotomy, the angle had opened up and you had at least 180 degrees in which the posterior trabecular meshwork was visible

IOP would be high [sp] of 21 to 30 mils of mercury. We excluded people with secondary angle closure, as well people with advanced glaucoma such as those with cup disc ratio of more than .9 or visual fields involving the central 10 degrees

This is [unintelligible] protocol with follow up visits at one week, four weeks, three months and six months

At every visit, IOP was measured by Goldmann applanation tonometry. And for the baseline and month six visits, we overtook [sp] IOP at 9 AM, 1 PM and 5 PM, and the mean IOP was taken for analysis

So, patients were randomized to either SLT or prostaglandin analogs - in this case, Travatan given at night

Through SLT, we give a drop of Brimonidine and Pilocarpine, and the SLT was delivered by the Latina lens. The laser power started at .6 and increased to .1 millijoules steps until you saw the champagne like bubbles. We performed approximately 100 to 115 non-overlapping shots over at least 180 degrees of the angle

And patients who had post laser IP specs of more than 5 millimeters of mercury were treated with oral Acetazolamide

All patients were given Prednisolone Acetate four times a day for one week

And if there was a--if the pressure was still high at either week four or month three visit, we allowed retreatment--one retreatment with SLT if there was a less than 20 percent reduction of IOP

We also allowed treatment modification for safety reasons if the IOP became uncontrolled. So, for this treatment, additional treatments were allowed, Timolol first followed by Dorzolamide and followed by Brimonidine

The primary outcome was a change in IOP from baseline through six months, and the secondary outcome was the proportion of patients who had IOP less than 21 as well as those who had less than 20 percent--more than 20 percent IOP reduction

So, here is--I present to you the preliminary results of the Singapore cases only. So, there were 60 randomized patients. We had 30 in SLT group and 30 in the prostaglandin group

This table summarizes the baseline characteristics of the patients. The mean age was similar as well as the proportion of males and females. The baseline IOP was also similar of 23 in SLT group and 22.4 in the prostaglandin group. And the XNPS [sp] was also similar

And most of the patients had PAC, and there was some PACG in both groups with a mean [unintelligible] ratio of .6 in both arms. The mean MD is also about point--minus 4.5 and minus 3.8

So, the mean area of SLT treatment was at least around 390 degrees, and the mean NG was 100 millijoules. We did an average of 128 laser shots. And some patients, seven out of 30 in SLT group, required a repeat laser. So, this was about 23 percent who required a repeat laser

This table summarizes the IOP response at six months. As you can see, the mean change in IOP was 4.8 millimeters of mercury or 20 percent in the SLT group, and similar, 4.1, or 18 percent, in the prostaglandin group. So, really, there was almost an identical response, you know, even slightly better response in SLD group compared with that of Travatan

If you break out the success rates by complete and qualified success, you can see that there was a 76 percent complete success in the SLT group and 16 percent in the qualified success in the SLT group. And this is comparable to that of the prostaglandin group

So, as this shows you, overall, a very good satisfactory IOP reduction in the SLT group

In terms of the percent of patients, more than 20 percent reduction from baseline, 50 percent had more than 13 percent had more than 30 percent reduction, and it was slightly better than the prostaglandin group of 36 percent who more than 20 percent reduction

And here, you show--this table summarizes the patients who had complete success only. And you can see here that the mean absolute reduction was five millimeters of mercury, and the mean percentage reduction was 21.7 percent

Some patients in the SLT group required additional medications. As I said earlier, five out of 30 or 16 percent were qualified successes that required additional medication, but the mean number of medications was only 0.33

And only one patient had an IOP spike of more than five millimeters of mercury, and this was satisfactorily treated with Acetazolamide

There were no other complications in both arms of the study and no patient had to require trabeculectomy or any other surgery

So, this is the first randomized controlled trial to evaluate the efficacy of SLT in patients with primary angle closure or primary angle closure glaucoma

As I mentioned earlier, in a previous study, SLT achieved a reduction of 1 to 8 percent when used as an adjunct to existing medications. In this study, there was no adjunct treatment, but it was a primary treatment. And we found similar efficacy to prostaglandin analogs in terms of mean IP reduction, percentage IP reduction, success rates as well as a number of patients who required additional treatments

So, these were eyes in which the angle had opened up after LPI. So, you have to remember, you cannot perform SLT for all the patients with angle closure glaucoma. For example, those in which the angles are still closed, you will not be able to perform this SLT treatment. It exists only for those in which the angle is widened sufficiently for you to see the trabecular meshwork in order to perform the SLT

We also excluded cases which were severe cases of angle closure glaucoma, and these cases probably would require trabeculectomy

We also found a very good safety profile. There were no significant side effects from the SLT, and only one patient had an IOP spike of more than five millimeters of mercury. Of course, the low rate of IOP spikes could be due to our use of preoperative Brimonidine as well as Pilocarpine

We believe that if far effective in long term, SLT may have overcome the barriers of compliance, cost, side effects and quality of life associated with chronic medical therapy and definitely is an alternative to medical therapy in [unintelligible] patients in which there's elevated IOP after a laser iridotomy

Of course, we know we need further studies to establish the long term efficacy and safety of SLT in angle closure

There were some limitations of this study. Firstly, the follow up period was only six months. We allowed a retreatment of SLT. So, 16 percent of patients were allowed to have a retreatment of SLT, one retreatment

The--this study was a short term, so we don't know the long term efficacy. And finally, there's not a double mass [sp] study

So, in summary, SLT appears to be an effective modality of IOP reduction in eyes with angle closure or PACG after LPI, at least for six months. The mean IOP reduction, percentage IOP reduction was [unintelligible] reduction was similar to the prostaglandin therapy at six months as well as the complete and qualified success rates in both arms of the study

Twenty-three patients of the SLT group required a repeat laser. There were no serious sequelae associated to laser therapy such as uncontrolled IOP or progression of peripheral [unintelligible]. So, I believe that SLT is an attractive option for you, for our patients who have angle closure after LPI in which the angle has opened up

I'd like to acknowledge my study team as well as my collaborators in Jakarta and the Chinese University of Hong Kong and grant funding from Ellex. Thank you for your attention