Purpose: To study the amount of laser energy used for double step laser iridotomy and its associated factors.
Methods: A total of 78 patients (142 eyes) with primary angle closure glaucoma, primary angle closure, and suspected primary angle closure who were scheduled to undergo neodymium yttrium aluminum garnet (Nd: YAG) laser iridotomy participated in the study. Of these, 62 were females and 16 were males; their mean ages were 72.5±8.5 years. In cases in which the procedure was performed in both the eyes, the eye that underwent the procedure first was analyzed. The iridotomy site was coagulated using 10 to 12 thermal laser shots. The incision was made using the Nd: YAG laser at 6.5 mJ/shot, and its associated factors were studied.
Results: The mean number of shots used in Nd: YAG laser iridotomy was 5.2±3.4 shots (1 to 12 shots) (33.8±21.5 mJ). A total of 13 eyes with iris hemorrhage received 9.5±4.0 shots (61.8±26.0 mJ) and 67 eyes without iris hemorrhage received 4.5±2.4 shots (29.3±15.6 mJ); this showed a significant difference between the two groups (p<0.0001). Patients without iris hemorrhage demonstrated a significant correlation between the Nd: YAG laser energy used and iris thickness (p<0.0001, R²=0.6121). A total of 32 eyes with an iris thickness of ≥ 330 μm received 5.9±2.8 shots (38.4±18.4 mJ) and 35 eyes with an iris thickness of< 330 μm received 3.2±0.9 shots (20.6±5.9 mJ) after the application of pilocarpine, which showed a significant difference between them (p<0.0001).
Conclusion: The amount of Nd: YAG laser energy used for laser iridotomy was significantly associated with the incidence of iris hemorrhage and pilocarpine-induced iris thickness.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 126: 178-182, 2022.