Fluctuation of the Intraocular Pressure during Intravitreal Injection

Abstract

Purpose: To measure fluctuations of intraocular pressure (IOP) during intravitreal injection. Materials and Methods: We worked with enucleated porcine eyes. Different volumes (0.05, 0.075, 0.1, 0.2, and 0.3 ml) of balanced salt solution (BSS) were injected into the vitreous cavity, with sham injection (0) serving as a control. IOPs were measured in real time using a digital manometer connected to a 26-gauge catheter at the anterior chamber. Results: At baseline, the mean IOP was 4.1 ± 0.3 mmHg in the anterior chamber. A transient peak of high pressure was observed when the injection needle penetrated the sclera. A volume effect created a second peak, followed by a return to baseline after the following times (s) corresponding to the following injections: 4.4 ± 2.0 (control), 169.7 ± 6.2 (0.05 ml), 587.7 ± 83.9 (0.075 ml), 1419.2 ± 132.5 (0.1 ml), 2,381.3 ± 149.7 (0.2 ml), and 1,419.2 ± 390.1 (0.3 ml). Conclusions: Two peaks appeared during injection. The height of the second peak and the extent of delay in recovery were dependent upon the injection volume. These results provide baseline values of IOP fluctuations during intravitreal injection.