The incidence and time distribution of early transient intraocular pressure elevation after penetrating canaloplasty

Abstract

Objective: To report the incidence and time distribution of early transient intraocular pressure (IOP) elevation after penetrating canaloplasty. Methods: Retrospective case series study. Data of patients treated by penetrating canaloplasty for glaucoma in the Eye Hospital of Wenzhou Medical University from June 2015 to March 2020 were collected. Early transient IOP elevation was defined as an increase of IOP to over 21 mmHg on the first week to the third month after surgery followed by a decrease to 21 mmHg or less within 3 months. Main outcome measures included IOP, quantity of medication use, the occurrence time and duration of IOP elevation. Generalized estimating equations were used for statistical analysis, and measurement data with non-normal distribution was represented as M (Q1, Q3). Results: A total of 277 patients (315 eyes) achieved 360-degree catheterization of the canal successfully, and 299 eyes (94.9%) completed the postoperative 6-month follow-up. Thirty-four eyes (10.8%) had persistently high IOP, so the surgical treatment failed in them. Consequently, 234 patients (265 eyes) were enrolled in the analyses, including 161 males (184 eyes) and 73 females (81 eyes). The median age was 42 (26, 54) years, the mean preoperative IOP was (37.7±11.1) mmHg, and the mean number of drugs used was 3 (2, 4). The incidence of early transient IOP elevation was 43.0% (114/265) in all enrolled eyes, 42.7% (35/82) in eyes with primary open angle glaucoma, 37.8% (17/45) in eyes with primary angle closure glaucoma, 27.7% (13/47) in eyes with congenital glaucoma and 53.8% (49/91) in eyes with secondary glaucoma. The IOP began to increase on the first to fourth week in 91.2% (104/114) of eyes with early transient IOP elevation and reached the peak [21.3 mmHg to 54.8 mmHg; mean, (32.4±8.2) mmHg] in 88.6% (101/114) on the first to fifth week after surgery. The IOP elevation lasted for no more than 4 weeks in 69.3% (79/114) of eyes. Conclusions: Over 40.0% of patients with penetrating canaloplasty may experience postoperative transient IOP elevation. The incidence is relatively high in secondary glaucoma but low in congenital glaucoma. Most of the elevations and peak IOP occur within 1-4 weeks after surgery.