Choroidal thickness and intraocular pressure after 25-gauge and 23-gauge vitrectomy for idiopathic epiretinal membrane

To determine the relationship between the subfoveal choroidal thickness (SCT) and intraocular pressure (IOP) following 25-gauge (25G) and 23-gauge (23G) vitrectomy for idiopathic epiretinal membrane (ERM). Retrospective, consecutive, interventional case series. Sixty-two patients undergoing 25G vitrectomy and 56 patients undergoing 23G vitrectomy for ERM participated. SCT was measured using enhanced depth imaging optical coherence tomography and IOP were measured both at baseline and postoperatively. In both groups, the IOPs on day one and one week after surgery were significantly lower than at baseline (P < 0.001 for both). The rates of changes of IOP were significantly greater in 23G compared to 25G on day one (P = 0.026). In 23G the SCTs on day one and one week after surgery were significantly thicker (P < 0.001) than baseline. The rates of changes in SCT between baseline and day one negatively correlated with those of IOP in 23G (r = −0.559, P < 0.001) but no correlation was observed with 25G (r = −0.129, P = 0.316). Choroidal thickness increases soon after 23G vitrectomy for ERM which is probably due to the transient hypotony, however, early SCT change does not appear in 25G vitrectomy. Twenty-five-gauge vitrectomy may have an advantage in minimizing postoperative choroidal changes.