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Kunjal K Modi, Scott M Walsman; Effect of Increasing Shot Number in Micropulse Laser Trabeculoplasty (MLT) for Open Angle Glaucoma. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4976.
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Our clinic initially set MLT laser parameters at 1,000 mW of power and 90-100 shots (spot 300 μm), and had a very minimal IOP reduction at 4-6 week follow up. We investigated if increasing the shot goal to >120 shots (still 1,000 mW and 300 μm spot) would lead to a larger reduction in pressure.
A review was conducted of patients with the diagnosis of primary open angle glaucoma (POAG), who had MLT treatment by ophthalmology residents at Rutgers-New Jersey Medical School in 2015-16. Patients were excluded if they had any diagnosis aside from POAG and if they did not have 4-6 week post-laser follow up. Patients who had treatment with the original settings (90-100 shots) were compared to patients who had treatment with the modified setting (>120 shots). Groups were compared based on overall IOP reduction (from 3 pre-laser visits), % reduction from Tmax, and percentage of eyes that achieved 25% reduction from pre-laser. Means were compared using a two-tailed student t-test or χ2 analysis (p<0.05=stat significant).
After exclusion criteria, 25 eyes remained for review; 15 with the original settings and 10 with the modified settings. For the original settings, the pre-laser and post-laser IOP was not clinically or statistically different (21.91 vs 20.57 mmHg, p=0.43). For the modified laser group, the pre and post-laser IOP also did not achieve statistical difference (19.05 vs 14.67, p=0.07), however trended toward better response.Table 1 shows that IOP at 4-6 week follow was significantly lower in the modified laser group, however this group also had a lower pre-laser IOP. The percentage reduction from Tmax and percentage reduction from the 3 pre-laser visits did not achieve significance in either group, but trended toward more reduction in the modified laser group. The percentage of eyes with 25% reduction at 4-6 week follow up was significantly increased in the modified group (13.3% vs 60.0%, p=0.01).
Significantly more eyes that received MLT with the modified settings achieved a 25% IOP reduction. Although the percentage reduction from Tmax and pre-treatment IOP was not significant in either group, both parameters trended toward better IOP reduction with the modified settings. As this data is limited by a small sample size, it would be beneficial to perform more MLT lasers at the modified settings to check for a true and sustained improvement in IOP reduction.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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