To investigate longitudinal changes in intraocular pressure (IOP), axial length (AL), and choroidal thickness (ChT) in primary open-angle glaucoma (POAG) eyes after trabeculectomy and to evaluate the parameters that might influence those changes.

In this prospective observational study, we recruited 28 patients with POAG (28 eyes) scheduled for trabeculectomy. The average macular ChTs and foveal retinal thicknesses along 6-mm segments centered on the fovea were examined preoperatively and postoperatively (at 1, 3, and 6 months) using swept-source optical coherence tomography. The IOP, AL, and mean deviation (MD) of standard automated perimetry (SAP) were also analyzed as independent variables.

Results from 16 patients were included in the final analysis. A significant increase in ChT with respect to the preoperative value was observed at every postoperative stage (1 month, P < 0.001; 3 months, P < 0.001; 6 months, P = 0.011), whereas the retinal thickness showed no significant change over the study period. The ChT increase and IOP reduction were sustained throughout the 6-month period without further significant changes. Stepwise multivariate analyses showed significant correlations between the percentage decrease in IOP and the percentage increase in ChT at 1 and 6 months postoperatively. The percentage increase in ChT was also significantly correlated with a better MD of the SAP at 1 month (β = 0.01; P = 0.009).

The ChT increase following trabeculectomy was sustained at 1, 3, and 6 months postoperatively. The percentage increase in ChT was significantly correlated with the percentage change in IOP and (more weakly) with better SAP MD values.