Purpose: 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.
Methods: 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.
Results: 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.
Conclusions: 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.