Purpose: Prospective, comparative, randomised study aiming at assessing the safety and the intraocular pressure (IOP) lowering effect of Micropulse Diode Laser Trabeculoplasty (810nm)(MDLT) and Argon Laser Trabeculoplasty in patients with open angle glaucoma.
Methods: 26 patients (mean age=67 years) were randomly assigned to undergo either MDLT (16 eyes) (66 applications, 100 msec, 0.6 mJ/pulse, 300 microm) or ALT (15 eyes) over 180 degrees. In 5 patients, MDLT was done in one eye and ALT in the other eye. Patients were followed for early IOP spikes and anterior segment inflammation. IOP was recorded at 1 day, 1 week, 1 and 3 months and 3 month intervals thereafter.
Results: Both groups were well-matched for age, glaucoma type, previous laser or surgical procedure, pre-treatment meds. Mean follow-up was 5.2 +/- 1.7 months for MDLT and 5.5 +/- 2.3 in ALT (p>0.05). Mean pre-treatment IOP was 20.7 +/- 3.8 mmHg and 21.6 +/- 4.2 mmHg in ALT respectively (p>0.05). Mean IOP was significantly reduced compared to the pre-treatment level in both groups at the different visits (p <0.05). At 3 months, the mean IOP was not significantly different in MDLT (18.6 +/- 5.1 mmHg) vs. ALT(16.7 +/- 3.3 mmHg) (p=0.26) while the mean IOP decrease was significantly less in MDLT (2.5 +/- 2.6 mmHg) than in ALT (4.9 +/- 3.4 mmHg) (p= 0.04). This corresponded to a mean percentage of IOP reduction of 12.2 +/- 11.9% in MDLT and 21.8 +/- 11.1% in ALT respectively (p=0.03), as well as an IOP drop > or =20% compared to the baseline IOP observed in 35.7% in MDLT versus 50% in ALT (p=0.03). At 3 months, the mean number of meds was significantly lower in MDLT (2.1 +/- 0.8) than in ALT (2.8 +/- 0.7) (p=0.03). MDLT was uneventful in 100% of patients with no thermal pain and no uncomfortable laser flashes. Anterior segment inflammation was absent or mild in both procedures. MDLT was associated with early moderate IOP spike in one eye with POAG.
Conclusion: At 3 months, Micropulse diode laser trabeculoplasty induced significantly less IOP reduction than ALT. The percentage of eyes with an IOP drop > or =20% was also significantly lower with diode laser than with argon laser trabeculoplasty. MDLT induced minimal anterior segment inflammation and seemed to exhibit a good safety profile. Its IOP efficacy should be still confirmed on a larger sample size and by modifying the treatment parameters.