Rates Of Cystoid Macular Edema In Anterior Chamber Vs Sulcus Tubes, With Or Without Concurrent Cataract Surgery

There is evidence that ciliary sulcus tube shunts can be associated with less corneal endothelial cell loss compared to anterior chamber (AC) tube shunts. However, sulcus tube shunts may be associated with a higher rate of postoperative cystoid macular edema (CME) than AC tube shunts. The purpose of this retrospective chart review is to compare CME rates in AC vs sulcus tubes, with or without concurrent cataract surgery.   

This retrospective chart review included all consecutive patients who underwent a Baerveldt-350 or ClearPath 350 with or without cataract extraction and intraocular lens implantation (CEIOL) from October 1, 2019 to December 31, 2023 at the University of Chicago Medical Center (Chicago, IL) with a single surgeon (MQ). Eyes were excluded if they did not have at least 3 months of follow up or had a tube shunt revision or exchange.

Cases were categorized into AC vs. sulcus groups. Data was collected on demographics and clinical features from the visit prior to surgery and postoperative month 3, 6, 12, 18, and 24 months, including vision, intraocular pressure (IOP), number of IOP-lowering medications, and complications including CME. Logistic regression analysis was performed to identify risk factors for CME.

67 eyes received standalone tube surgery, and 53 eyes were combined with cataract surgery (47 AC vs. 73 sulcus tubes). On average, patients were 68 years old, 48% male, 78% Black, and 58% had primary open angle glaucoma. Patient’s IOP decreased from 25 mmHg on 4 IOP-lowering medications to 13 mmHg on 2 IOP-lowering medications at 12 (N=68) and 24 months (N=27), with an average follow-up of 17 months. The CME rate was 23% in AC and 33% in sulcus tubes, but this was not statistically significant. Eyes that received concurrent cataract surgery had a CME rate of 35% in AC and 36% in sulcus tubes. Pseudophakic eyes that received standalone tubes had a CME rate of 17% in AC and 30% in sulcus tubes, but this was not statistically significant.

Patients who underwent an AC or sulcus tube combined with cataract surgery may have higher rates of CME largely driven by the phacoemulsification portion of the surgery. On the other hand, pseudophakic eyes undergoing standalone tubes may have a higher rate of CME with sulcus tubes compared to AC tubes. These results warrant further investigation on a larger scale, both retrospectively and prospectively. Future studies performed at an institution with a greater total number of tube shunt surgeries or a multi-institutional analysis could help further investigate whether AC vs sulcus tube placement is associated with post-operative CME.