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D. De Silva, P. J. Foster; A Randomized Controlled Trial to Evaluate Laser Peripheral Iridotomy With Nd:YAG Laser Against Sequential Argon-Nd:YAG Laser in Dark Irises. Invest. Ophthalmol. Vis. Sci. 2009;50(13):163.
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Laser iridotomy is the established treatment of angle-closure glaucoma. Nd:YAG laser iridotomy is challenging in the heavily pigmented irises of African and Asian patients with high failure rates and complications. We carried out a randomized controlled single-centre trial to compare the outcome of Nd:YAG versus sequential argon-Nd:YAG laser iridotomy in people dark irises.
For each patient, one eye was randomized to unilateral Nd:YAG laser treatment and the fellow eye received sequential argon-Nd:YAG laser. The argon laser was applied in 2 stages; firstly, low power argon which created a circular area of pitted iris stroma in the superior iris. Secondly, high power argon was applied to the same area and a punched out crater formed at the level of the radial muscle fibers. The iridotomy was then completed with low energy Nd:YAG laser. IOP, angle width and any intra- or post laser complications were noted.
Thirty patients were enrolled in the trial; 17 Asian and 13 African patients (mean age 60±11years, 10 men, 20 women, mean follow up: 15±9 weeks). Hemorrhage was significantly more frequent in the Nd:YAG laser treated eyes than in eyes undergoing sequential argon-YAG iridotomy (12 eyes, 40% vs. 1 eye, 3%, chi sq 11.88, P= 0.0006). Similarly, the Nd:YAG treated eyes more often required a break in treatment of 30 minutes to allow blood or pigment to clear (10 eyes, 33.3% vs. 3 eyes, 10%; chi sq 4.81, P= 0.028) before completion of treatment. Re-treatment rates were higher but not statistically significant in Nd:YAG eyes than in sequential laser treated eyes; week 1: 10% versus 0% (chi 3.16, P= 0.075); weeks 1-12: 16.6% vs. 6.6% (chi sq 1.46, P= 0.23).
Iridotomy by Nd:YAG laser alone more commonly resulted in iris hemorrhage and required prolonged or multiple treatments, compared with sequential argon-Nd:YAG laser iridotomy in people dark irises.
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