Phenylephrine eye drops in ophthalmic surgery--a clinical study on cardiovascular effects

Phenylephrine in concentrations of either 2.5% or 10% is widely used as a mydriatic agent in ophthalmic surgery. Its potential cardiovascular effects are seldom recorded as ophthalmic surgery is not usually monitored by an anaesthetist. A prospective randomised double blind study was carried out in 89 consecutive cases of uncomplicated cataract surgery in the presence of an anaesthesiologist ensuring the continuous monitoring of blood pressure, heart rate, electrocardiography and pulse oximetry. All these patients were given a drop of either normal saline, 2.5% or 10% phenylephrine in addition to mydriacyl prior to surgery. Blood pressure readings were found to be significantly higher in non-hypertensive patients receiving phenylephrine at the start of the operation and at five, 10, 15 and 20 minutes intra-operatively and the first three hours post-operatively. Blood pressure readings in hypertensive patients, on the other hand, were also found to increase after phenylephrine administration, though not statistically significant. 10.3% of the 10% phenylephrine group and 3% of the 2.5% phenylephrine group required intraoperative intravenous hypotensive agent to control the blood pressure. There were no arrhythmias or ischaemic changes observed intraoperatively. None of the patients complained of palpitation, headache or chest discomfort. There was no oxygen desaturation observed. We concluded that significant hypertensive effects can arise after phenylephrine eye drop administration. Hence, it should be used cautiously with intraoperative monitoring of the cardiovascular status during cataract surgery.