Risk factors for persistent inflammation post-laser peripheral iridotomy

Purpose: To investigate risk factors associated with persistent inflammation after Laser Peripheral Iridotomy (LPI). Methods: We performed a single-center, retrospective, case-control study of patients with primary angle closure suspicion, primary angle closure glaucoma, or chronic angle closure glaucoma treated with Laser Peripheral Iridotomy between April 1, 2016 and April 30, 2019. Parameters investigated included patient demographics, ocular history, laser settings, surgeon experience, and medication compliance. Persistent inflammation was defined as the presence of cells and/or flare at the first follow-up visit despite prophylactic treatment with prednisolone acetate 1% four times a day for 1 week. We performed Fisher’s exact tests and two-sample t-tests to identify risk factors associated with persistent inflammation. Results: 203 patients were included of which 16 (7.9%) met criteria for persistent inflammation following LPI. Risk factors associated with persistent inflammation included pre-treatment with argon laser (p=0.045). The mean argon energy and exposures was 741.9 ± 108.9 mW and 262 ± 242 counts in the persistent inflammation group verses and 533.8 ± 302.4 mW and 113 ± 131 counts in the no inflammation group (p<0.001 and p=0.027 respectively). Persistent inflammation was associated with ≤ 5 years of surgeon experience (p=0.03615, OR=3.19). Patient demographics (age, gender or race), LPI location and Nd-Yag laser parameters were not associated with persistent inflammation. Conclusion: We demonstrate an association between mean argon laser energy, exposure count and surgeon inexperience and persistent inflammation following LPI. We hope identifying risk factors can help guide interventions to minimize post-operative inflammation in a common laser procedure in glaucoma