# Comparison of Surgically Induced Astigmatism Between Baerveldt Glaucoma Implant Surgery and Trabeculectomy: A Retrospective Cohort Study

## TL;DR

This study compares how much corneal astigmatism is caused by two glaucoma surgeries and finds that one causes more astigmatism than the other.

## Contribution

The study provides a direct comparison of surgically induced astigmatism between Baerveldt glaucoma implant surgery and trabeculectomy.

## Key findings

- BGI surgery caused greater surgically induced astigmatism than trabeculectomy.
- BGI surgery and lower preoperative astigmatism were independently linked to greater postoperative astigmatism.
- Older age predicted more astigmatism after BGI surgery but not after trabeculectomy.

## Abstract

Objectives: This study aimed to compare surgically induced corneal astigmatism (SIA) between Baerveldt glaucoma implant (BGI) surgery and trabeculectomy and to identify prognostic factors associated with SIA. Methods: This retrospective cohort study included 109 and 229 eyes that underwent BGI surgery and trabeculectomy, respectively, at Fukui University Hospital. Corneal astigmatism was assessed preoperatively, and at 6 months postoperatively, the mean SIA (M-SIA) and centroid SIA were calculated, and factors associated with M-SIA were determined. Results: BGI surgery was associated with greater SIA than trabeculectomy. Postoperative corneal astigmatism was −1.53 ± 1.01 D in the BGI group and −1.33 ± 0.92 D in the trabeculectomy group (p = 0.044). The M-SIA was significantly larger in the BGI group (1.41 ± 1.05 D vs. 0.94 ± 0.74 D, p < 0.01). Multivariate regression revealed that BGI surgery and lower preoperative corneal astigmatism were independently associated with greater M-SIA. Subgroup analysis revealed that older age and lower preoperative astigmatism were significant predictors of larger M-SIA in the BGI group, whereas only preoperative astigmatism was significant in the trabeculectomy group. Conclusions: BGI surgery was associated with greater and more variable SIA than trabeculectomy. Surgical type, baseline astigmatism, and age are important predictors of postoperative SIA.