High-intensity focused ultrasound cycloplasty: Analysis of pupil dynamics

Abstract

Aim: High-intensity focused ultrasound cystoplasty (UCP) aims to noninvasively and selectively target the ciliary body, thus lowering intraocular pressure (IOP). To be used on a large scale, the safety of the UCP procedure should be studied. Therefore, its effect on pupil behavior is important to better inform patients and to help physicians predict possible treatment side effects. This study aimed to evaluate to what extent UCP procedure (EyeOP-1®) affects pupil dynamics. Materials and methods: Consecutive glaucoma patients with uncontrolled IOP despite optimal medication scheduled for UCP treatment were recruited and followed for 6 months. Pupillometry (PlusoptiX® S04) was performed at baseline, and 1, 3 and 6 months after UCP procedure at scotopic and mesopic conditions. The difference between pupil diameter (PD) in both lighting conditions was calculated at the three follow-up visits. Demographic, clinical characteristics and specific ocular parameters (anterior chamber depth and volume, white-to-white measurement, axial length, phakic status) were registered. Statistical analysis was performed using STATA 14.1. Results: Sixteen eyes of 16 patients with a mean age of 69 ± 11 years were included. Mean preoperative IOP and number of medications were 23.6 ± 3.0 mm Hg and 2.4 ± 1.3, respectively. Mean baseline scotopic and mesopic PD were 4.8 ± 0.8 mm and 4.4 ± 0.9 mm, respectively (difference = 0.38 ± 0.30 mm; range 0.1 to 1.2 mm). At month-1, the pupil diameter (PD) change between scotopic (4.6 ± 0.7 mm) and mesopic (4.5 ± 0.8 mm) conditions decreased to 0.03 ± 0.34 mm, p = 0.01. On the longer follow-up periods, however, the amplitude difference in PD compared to baseline was no longer significant (month-3: 0.28 ± 0.49 mm; month 6: 0.23 ± 0.41 mm; p >0.05). At the end of follow-up, mean scotopic and mesopic PD were 4.7 ± 1.0 mm and 4.4 ± 0.9 mm, respectively. Conclusion and clinical significance: In the early postoperative period after UCP treatment, most patients present with a less light-reactive pupil, which seems to normalize with time.