Comparison of New Visual Disturbances after Superior versus Nasal/Temporal Laser Peripheral Iridotomy: A Prospective Randomized Trial

Purpose: To determine whether laser peripheral iridotomy (LPI) location affects postoperative dysphotopsia symptoms. Design: Multicenter, randomized, prospective, single-masked trial. Participants: Five hundred fifty-nine South Indian patients 30 years of age or older diagnosed as primary angle-closure suspects (PACSs) or with primary angle closure (PAC) or primary angle-closure glaucoma (PACG) in both eyes. Methods: Patients were randomized to either bilateral superior or bilateral nasal/temporal LPI. Occurrence of new visual disturbances was evaluated before and 2 weeks after LPI using a questionnaire based on the 7-item dysphotopsia symptoms described by Spaeth et al. Main Outcome Measures: New-onset dysphotopsia symptoms. Results: Superior LPI (n = 285) and nasal/temporal LPI (n = 274) patients were matched for age (P = 0.6), gender (P = 0.7), and distribution of PACS versus PAC or PACG (P = 0.7). Similar initial laser energy settings were used in both groups (P = 0.3), although superior LPIs required more shots (P = 0.006) and greater total energy (P < 0.001) than nasal/temporal LPIs. No significant differences in postoperative anterior chamber reaction (P = 0.7) or LPI area (P = 0.9) were noted between the 2 groups. No group differences were noted regarding the proportion of patients demonstrating 1 or more dysphotopsia symptoms before LPI (15.8% for superior vs. 13.9% for nasal/temporal; P = 0.1) or any individual dysphotopsia symptom (P > 0.2 for all). After LPI, 8.9% of all patients reported 1 or more new symptoms, the most common consisting of linear dysphotopsias, glare, and blurring in 2.7%, 4.3%, and 4.3% of patients, respectively. Patients undergoing superior LPI were not more likely to describe the new onset of 1 or more dysphotopsia symptoms as compared with patients undergoing nasal/temporal LPI (8.4% vs. 9.5%; P = 0.7), nor did the frequency of any new individual symptoms differ by group (P ≥ 0.3 for all). In multivariate logistic regression analysis, neither LPI location nor LPI area nor total laser energy predicted higher odds of new postoperative dysphotopsias (P > 0.1 for all). Conclusions: Laser peripheral iridotomy likely is safe with respect to visual dysphotopsias regardless of location, LPI size, and amount of laser energy used.