We investigated the long-term longitudinal changes in axial length (AL), mean ocular perfusion pressure (MOPP), and choroidal thickness (CT) according to the reduction of intraocular pressure (IOP) after glaucoma surgery. The potential variables associated with CT changes were also evaluated. Methods

This was a prospective study for 1 year after glaucoma surgery, which included 71 eyes of 71 patients with primary open-angle glaucoma. The subfoveal CT (SFCT) and peripapillary CT (PPCT) were measured using spectral-domain optical coherence tomography preoperatively and 1 week, 1 month, 2 months, 6 months, and 1 year postoperatively. MOPP was calculated from the IOP and blood pressure. The AL was measured using partial coherence interferometry. Regression analysis was conducted to assess the possible association of variables. Results

The AL decreased and the MOPP, SFCT, and PPCT increased significantly with IOP reduction at 1 year post-operatively (all, p < 0.001). The changes in SFCT and PPCT were significantly associated with IOP reduction at 1 year postoperatively (r = −0.519 and r = −0.528, respectively). Importantly, greater increases in SFCT and PPCT were found in patients with IOP reduction more than 30% from baseline, when compared with those with less than 30% reduction ( p = 0.001 and p = 0.002, respectively). The SFCT increased more significantly in patients with AL ≤ 24 mm, compared with patients with AL > 24 mm ( p = 0.044). Conclusions

Reduction in the IOP, increase in the MOPP, decrease in the AL, and increase in the CT after glaucoma surgery persisted for 1 year during a long-term follow-up. These results suggested that glaucoma surgery reduced mechanical compression on the optic nerve fiber and increased intraocular blood flow.