Effect of Prophylactic Medication and Influence of Vitreous Reflux in Pressure Rise after Intravitreal Injections of Anti-VEGF Drugs

Abstract

To assess the efficacy of a hypotensive prophylactic medication in preventing intraocular pressure (IOP) changes after intravitreal injections, and the effect of occurrence of vitreous reflux on the variation of IOP. A total of 141 intravitreal injections of anti-vascular endothelial growth factor drugs (0.05 mL) were randomly distributed into 2 groups: in group 1 (n = 77), no prophylactic IOP-lowering medication was used; in group 2 (n = 64), a fixed combination of brimonidine and timolol was instilled 5 minutes before the injection. The IOP was measured before and 1, 15, and 30 minutes after the injection. The presence of vitreous reflux was recorded. Despite significantly reducing the IOP by ~3 mm Hg, prophylactic medication did not prevent a transient IOP rise. A total of 22.7% of injections showed vitreous reflux, and those patients experienced much lower initial spikes. Indeed, only 6.5% out of 77 injections above 30 mm Hg within 1 minute after injection showed vitreous reflux. Only one case showed an IOP >30 mm Hg at 15 minutes, and none at 30 minutes postinjection. The IOP normalization rates over time were similar in all groups within 15 minutes. Prophylactic medication instilled 5 minutes before the injection was not effective in preventing a pressure rise after intravitreal injections. Vitreous reflux decreased significantly the spike figures compared to injections with no reflux.