Posterior chamber injection of intracameral mydriatics increases the durability of the mydriatic response

Abstract

To compare the mydriatic effect of intracameral mydriatics injected into the anterior or the posterior chamber in routine phacoemulsification cataract surgery. Forty-four patients planned for unilateral phacoemulsification surgery were included after informed consent. Mydriasis was achieved by injecting 150 μl of a mixture of phenylephrine 1.5% and lidocaine 1.0% at the beginning of the procedure. The patients were randomly assigned to injection into the anterior or the posterior chamber. The pupils were filmed during the procedures, and the mean pupil diameters were measured at predetermined intervals from the video recordings by an independent observer. Immediately after the injection, the pupils were larger after posterior chamber injection (3.8 ± 0.8 versus 3.1 ± 0.7 mm; p = 0.004). A similar difference was seen after the phacoemulsification (6.4 ± 0.7 versus 5.9 ± 1.0 mm; p = 0.031). The mydriatic durability was also better after posterior injection (p = 0.004-0.041). Apart from immediately after the injection, the initial mydriatic response was similar with both injection techniques, but the durability of the mydriasis was slightly better after a posterior chamber injection of ICM.