Correlation between choroidal thickness and intraocular pressure after 23-gauge vitrectomy for idiopathic epiretinal membrane

Abstract

To determine the relationship between the subfoveal choroidal thickness (CT) and intraocular pressure (IOP) following idiopathic epiretinal membrane (ERM) surgery. Retrospective observational case series of patients who had undergone 23-gauge vitrectomy for an ERM. The measurements of CT and IOP were done at the baseline and 1d, 1wk, 1, 3, 6, and 12mo after the surgery. Forty-four eyes of 43 patients with a mean age of 69.8±9.5y were studied. The CT was 200.8±86.3 µm at the baseline, 210.1±83.5 µm at 1d, 213.2±85.4 µm at 1wk, 203.1±84.0 µm at 1mo, 197.5±85.5 µm at 3mo, 197.7±84.0 µm at 6mo, and 191.2±86.8 µm at 12mo after surgery. The CT on day 1 and week 1 after the surgery was significantly thicker than that at the baseline CT (P=0.0023 and P<0.0001). The CT at 12mo after surgery was significantly thinner than the baseline (P=0.0062). The IOP on day 1 and week 1 were significantly lower than the baseline (P<0.0001 and P=0.0042). The IOP at 1, 3, 6, and 12mo after surgery were significantly higher than the baseline IOP (P=0.0087, P=0.0023, P<0.00051, and P<0.0001). The rates of changes in the CT between baseline and day 1 and week 1 were significantly and negatively correlated with the rates of change in the IOP (P<0.0001 and P=0.046). In the group with the IOP change rate of -30% or less at 1d postoperatively, the change rate of CT was -21.1% to 31.2% (9.8%±12.4%) and in the group of -29% or more, it was -8.9% to 28.0% (2.6%±8.9%). The change rate of CT in the group with the IOP change rate of -30% or less was significantly higher than the group of -29% or more (P=0.016). CT increases soon after the ERM surgery which is probably due to the transient hypotony, showing that IOP may be a significant confounding factor for CT.