Comparison of Diode-Pumped, Frequency-Doubled Neodymium: YAG Laser and Blue-Green Argon Laser Iridotomy

ABSTRACT

PURPOSE: The solid-state, continuous-wave, frequency-doubled neodymiumyttrium-aluminum-garnet (NdYAG) laser pumped by diode laser has several advantages, including air cooling, higher electrical to optical efficiency ratios, and portability. The authors evaluated the use of the frequency-doubled NdYAG laser for peripheral iridotomy and compared with the argon blue-green laser. METHODS: Laser peripheral iridotomy was performed on 64 eyes of 47 patients with acute or chronic primary angle-closure glaucoma and narrow angles capable of closure. Thirty-one eyes of 25 patients were treated with frequency-doubled NdYAG laser and 33 eyes of 22 patients were treated with argon laser. Postoperative intraocular pressure, visual acuity, preoperative and postoperative medication, number of laser spots, and failure of patency were compared. RESULTS: Postlaser 1hr intraocular pressure elevation greater than 10 mmHg 1hr was seen in one (3.2%) of frequency-doubled NdYAG laser treated eyes and six (17.6%) of argon laser-treated eyes (p=0.055). The failure of patency was seen less often in frequency-doubled NdYAG laser than in argon laser (9.7% vs 27.3%, p=0.081). The number of laser spots was greater in frequency-doubled NdYAG laser than in argon laser (p=0.069). Preoperative, postoperative 1hr, 1day, 1mon, 3mons intraocular pressure, visual acuity, preoperative and postoperative antiglaucomatous medication, number of laser spots, and failure of patency were similar in the two groups. CONCLUSIONS: The above results suggest that the frequency-doubled NdYAG laser was at least as effective and appears to be as safe as the argon laser. However, laser iridotomy with frequency-doubled NdYAG laser may be more difficult than the argon laser.