Systemic exposure to intracameral vs topical mydriatic agents: in cataract surgery

The objective of this study was to compare systemic exposure to tropicamide/phenylephrine following intracameral or topical administration before cataract surgery.

Mydriatics exposure was calculated in patients randomized to intracameral fixed combination of mydriatics and anesthetic ([ICMA]: tropicamide 0.02%, phenylephrine 0.31%, and lidocaine 1%, N=271) or mydriatic eye drops ([EDs]: tropicamide 0.5% and phenylephrine 10%, N=283). Additional doses were permitted if required. Mydriatic plasma levels were determined by mass spectrometric HPLC in 15 patients per group before and after administration.

Most ICMA patients (73.6%) received a single dose (200 µL) representing an exposure to tropicamide of 0.04 mg and phenylephrine of 0.62 mg. None of these patients received additional mydriatics. In the control group (three administrations), the exposure was 0.45 (11.3-fold higher than ICMA) and 10.2 (16.5-fold higher) mg. When additional ED was used in this group (9.2% of patients), it was 37.5-fold higher for tropicamide (10 drops, 1.5 mg) and 54.8-fold higher for phenylephrine (10 drops, 34 mg) than the recommended ICMA dose. Tropicamide plasma levels were not detectable at any time point in ICMA patients while it was detectable in all ED patients at 12 and 30 minutes. Phenylephrine was detectable in 14.3% of ICMA patients compared to all ED patients at least at one time point. More ED patients experienced a meaningful increase in blood pressure and/or heart rate (11.2% vs 6.0% of ICMA patients; P=0.03).

Systemic exposure to tropicamide/phenylephrine was lower and cardiovascular (CV) effects were less frequent with ICMA. This could be of particular significance in patients at CV risk.