The mydriatic effect of intracameral epinine hydrochloride

To compare the mydriatic effect and the short-term corneal endothelial safety of intracamerally injected N-methyl-3,4-dihydroxyphenylamine (epinine) to phenylephrine in a porcine eye model.

One hundred twelve eyes from newly slaughtered pigs were used in this study. After pretreatment with 20 mg intracameral acetylcholine to give miosis, 0.15 mL epinine or phenylephrine 0.3%, 1.5%, or 3.0% was given as an intracameral injection. The pupils were filmed during 90 seconds with a video camera connected to an operation microscope, and the mean pupil diameters were measured from the video recordings. In 37 additional eyes, 0.15 mL vehicle, 1.5% epinine, or 1.5% phenylephrine was injected intracamerally, and the eyes were kept on ice overnight. Corneal endothelial morphology was assessed before and after the treatment. Ten eyes were given no injection and served as controls. RESULTS; Epinine had a significantly larger mydriatic effect than phenylephrine at equal concentrations. Endothelial cell loss was equal with both substances and did not exceed that of the vehicle.

Epinine was a more potent mydriatic than phenylephrine in this porcine eye model. The porcine eye model appears suitable as a first efficacy screening of substances for intraocular use. Epinine is a promising candidate substance for intraoperative (e.g., cataract surgery) intracameral use in humans.