Micropulse diode laser trabeculoplasty (MDLT): A phase II clinical study with 12 months follow-up

Abstract

ObjectiveThis pilot study evaluates the pressure lowering potential of subthreshold micropulse diode laser trabeculoplasty (MDLT) for a clinically meaningful duration in patients with medically uncontrolled open angle glaucoma (OAG).Designprospective interventional case series.ParticipantsThirty-two eyes of 20 consecutive patients with uncontrolled OAG (12 bilateral and 8 unilateral).MethodsConfluent subthreshold laser applications over the inferior 180° of the anterior TM using an 810 nm diode laser in a micropulse operating mode. The intraocular pressure (IOP) was measured at baseline and at 1 hour, 1 day, 1 week, 3, 6, 9, and 12 months post-treatment. Flare was measured with a Kowa FM 500 flare-meter at baseline and at 3 hours, 1 day, 1 week, and 12 months post-treatment. After treatment, the patients were maintained on their pre-treatment drug regimen.Main outcome measuresCriteria for treatment response were IOP reduction ≥3 mm Hg and IOP ≤21 mm Hg within the first week after MDLT. Eyes not complying to the above criteria during the follow-up were considered treatment failure. Mean IOP change and percentage of IOP reduction during the follow-up were calculated.ResultsOne eye was analyzed for bilateral patients. A total of 20 eyes were thus included. Four eyes (20%) did not respond to treatment during the first week. One additional eye failed at the 6 month visit. The treatment was successful in 15 eyes (75%) at 12 months. The IOP was significantly lower throughout follow-up (p < 0.01). At 12 months, the mean percentage of IOP reduction in the 15 respondent eyes was 22.1% and 12 eyes (60%) had IOP reduction higher than 20%. During the first two postoperative days, one eye with pigmentary glaucoma experienced a significant increase of flare associated with an IOP spike (34 mm Hg) that was controlled with systemic drugs; afterwards it qualified as a respondent and completed the study. No increase of flare was found in any other patient. No peripheral anterior synechiae formed.ConclusionsIn this case series, MDLT was effective in reducing IOP in 75% of medically insufficiently controlled OAG eyes without significant complications. This justifies randomized clinical studies to compare MDLT with current IOP lowering strategies.

Selective laser trabeculoplasty vs micropulse laser trabeculoplasty in open-angle glaucoma

“…The success rates for MLT were higher than some previously reported studies involved in achieving the goal of ≥3 mmHg IOP or ≥20.0% IOP reduction from baseline values, although one author utilized the 810 nm diode laser12 and the other only targeted the inferior meshwork 15. Our findings were also less efficacious than some reports, but had a smaller sample size11 and included shorter intervals of follow-up 16…”

“…Prior laser treatments may confound the results in both groups, in addition to the lack of a washout period. These prior laser and medical treatments may also explain the relatively low success rate of trabeculoplasty in both groups compared to other studies 11,16. The examiners and patients were not blinded to the laser treatments, although this was offset by the strict, set randomization sequence.…”

“…Recruitment was concluded after a power analysis revealed an 80% power at a 0.05 α level detecting an average 2.99 mmHg or 16.19% decrease from baseline between the SLT and MLT groups. This level was determined based on prior studies defining a ≥3 mmHg or ≥20.0% decrease in IOP as a significant difference from baseline 11. Patients, physicians, and researchers were not blinded to the different laser treatments.…”

Morphologic Changes in Trabecular Meshwork after Patterned and Argon Laser Trabeculoplasty in Cats

“…[7][8][9] Several modifications have been made to laser trabeculoplasty to maximize its effect and minimize its potential disadvantages. [10][11][12][13][14][15] In particular, patterned laser trabeculoplasty (PLT) was recently introduced. 16 This technique has the advantage of providing uniform coverage of the trabecular meshwork with large number of exposures using the pattern scanning system of PASCAL.…”

Randomized Controlled Comparison of Titanium-Sapphire Versus Standard Q-Switched Nd:YAG Laser Trabeculoplasty

“…L aser trabeculoplasty has used a variety of wavelengths across the visible and invisible light spectrum including argon laser trabeculoplasty (ALT, 488 nm 1,2 and 514 nm 3 ), selective laser trabeculoplasty (SLT, 532 nm), 3 krypton yellow (568 nm), 4 krypton red (647 nm), 4 titanium-sapphire laser (TLT, 790 nm), micropulse (MLT, 810 nm), 5 and neodymium-YAG laser (1064 nm). 6 These lasers have distinctly different physical and biological effects that are determined by their wavelength and resulting tissue penetration depth as well as by what structures and pigments absorb the energy over what time period.…”