Comparison of the effects of remifentanil and alfentanil on intraocular pressure in cataract surgery.

Background: Anesthesia for ophthalmic surgery requires management of intraocular pressure (IOP) during perioperative period. In an open eye, in conditions such as after traumatic injury or during cataract surgery, IOP increase can lead to permanent vision loss. Administration of narcotics concomitant with anesthetics has the ability to reduce this increase of IOP. This clinical trial aims to compare the efficacy of remifentanil and alfentanil in preventing an increase in IOP after administration of succinylcholine, intubation and during anesthesia.

Methods: This double-blind clinical trial was conducted on 50 patients undergoing elective general surgery for cataracts. Patients were randomly divided into two groups. Alfentanil (20 μg/kg in 30 s) for group 1 and remifentanil (1 μg/kg in 30 s) for group 2 were injected before induction of anesthesia, and 0.5 μg/kg/min alfentanil for group 1 and 0.1 μg/kg/min remifentanil for group 2 were infused during the anesthesia. Systolic and diastolic blood pressure, heart rate, and IOP from normal eye were measured before the induction, after administration of thiopental and succinylcholine, after tracheal intubation, and 2 min later, and were repeated in 2-min intervals until the end of operation.

Results: IOP decreased after injection of anesthetics and remained lower all through the operation in both groups, but IOP decreased after injection of succinylcholine in remifentanil group while it increased in alfentanil group (P<0.05).

Conclusions: Results of this study indicate benefits of both remifentanil and alfentanil in managing IOP after induction and during anesthesia. It seems that remifentanil is better than alfentanil in controlling the IOP after injection of succinylcholine.