Pupillary Abnormalities After Micropulse Transscleral Cyclophotocoagulation

Abstract

Purpose : To evaluate pupillary abnormalities in patients who underwent Micropulse Transscleral Cyclophotocoagulation (MP-TSCPC).

Methods : The retrospective IRB approved study included 349 patients who underwent MP-TSCPC between March 2016 and August 2019 at Mayo Clinic, Florida. Preoperative and postoperative best corrected visual acuity, refractive error, intraocular pressure, number of medications, visual field, OCT and post-surgical complications were measured. Success criteria were defined as IOP reduction ≥ 20% and BCVA loss ≤ 2 lines. All patients were treated with a laser power of 2000 mW and duty cycle of 31.33%. Treatment time was 80 seconds for each 180° hemisphere, totaling 160 seconds covering the entire 360°. Patients with pupillary abnormalities had slit lamp photographs taken to document iris color and anterior segment OCT was done in both light and dark conditions for qualitative assessment of pupillary diameter.

Results : Of the 349 patients, 75% were female with mean age 66.25 ± 8.73 years. No patients had macular complications after MP-TSCPC. Four patients presented with fixed and dilated pupils that did not react to light or accommodate after the procedure. All four patients had brown irises and myopia, 50% were phakic and 75% had severe glaucoma. The mean preoperative and postoperative IOP was 14.75 mmHg and 13.5 mmHg, respectively. The mean number of medications was 2.5 (pre-operative) and 2.25 (postoperative). The mean preoperative and postoperative LogMAR vision was 0.27 and 0.25, respectively.

Conclusions : MP-TSCPC may be an effective therapy for glaucoma but an uncommon adverse effect is postoperative reversible fixed mydriasis. Cases involving pupillary abnormalities have not been previously described. Mechanism of this condition is likely multifactorial. Broadly accepted theories are ischemic atrophy of iris sphincter muscle secondary to iris strangulation, with resultant pupil dilation and acute rise in IOP leading to iris vessel occlusion and iris ischemia. Myopic females with brown iris had higher chances of having this complication. Pupil abnormalities resolved on their own in all patients within three months. Further studies with variable laser settings, larger sample size, cohorts and extended follow up are needed to identify patients at higher risk.

This is a 2020 ARVO Annual Meeting abstract.