Changes in choroidal thickness after intraocular pressure reduction following trabeculectomy.

Abstract

To evaluate the changes of peripapillary and subfoveal choroidal thickness (CT) after trabeculectomy. Prospective longitudinal study included 37 eyes with open-angle glaucoma. The subfoveal and peripapillary CT was measured using enhanced depth imaging spectral domain optical coherence tomography before trabeculectomy and 1week, 3 and 6months postoperatively. The associations between changes in the CT, intraocular pressure (IOP) and axial length were analysed. The medium subfoveal CT (IQR) increased from 182 (97)μm at baseline to 267 (107)μm 1week, 213 (97)μm 3months and 207 (91)μm 6months postoperatively (p<0.001). The peripapillary CT increased in all four quadrants at all follow-ups (p<0.05). The subfoveal and peripapillary choroidal thickening correlated with the magnitude of IOP reduction (p<0.05) and axial length shortening (p<0.01) during whole follow-up period. There was a peripapillary CT increase of 2.9μm per mmHg of IOP reduction (p<0.001, CI 1.5-4.4) and 4.8μm per mm of baseline axial length (p=0.049, CI 0.03-9.6) 1week postoperatively after adjustment for baseline IOP. Six months postoperatively, the decrease in axial length was the only factor associated withperipapillary choroidal thickening (p=0.031; regression coefficient: 73.29μm/mm, CI 7.1-139.5). Intraocular pressure (IOP) reduction after trabeculectomy caused the increase in subfoveal and peripapillary CT for at least 6months postoperatively correlating with greater IOP reduction and axial length shortening. In the long term, the decrease in axial eye length, but not IOP, was the only factor to be associated with peripapillary choroidal thickening.