Background: This study investigated the efficacy and safety of intracameral injection of commercially available eye drops containing 0.5% tropicamide and 0.5% phenylephrine hydrochloride (Mydrin-P, Santen Pharmaceutical, Osaka, Japan).
Design: In vitro experiment and prospective clinical study at a private hospital.
Participants and samples: Mydrin-P was applied to confluent cultured human corneal endothelial cells, and the cellular morphology was examined. Clinical study subjects were 65 eyes of 65 patients that underwent phaco-emulsification and aspiration with intraocular lens implantation and received intracameral injection of Mydrin-P for poor mydriasis after preoperative topical instillation of mydriatics (intraocular mydriasis group; with five subgroups based on cause: diabetes, pseudo-exfoliation, post-surgery, uveitis, unknown). Controls, comprising 39 eyes of 39 patients, were not injected with Mydrin-P.
Methods: The ratio of pupillary diameter to corneal diameter was determined before and after injection of Mydrin-P. Corneal endothelial density was measured preoperatively and 3 months and 1 year postoperatively.
Main outcome measures: Pupillary diameter and corneal endothelial density.
Results: Human corneal endothelial cell morphology was unaltered after Mydrin-P injection. The mean ratio of the pupillary diameter to corneal diameter increased in the intraocular mydriasis group (before: 54.2 ± 4.8%, after: 58.4 ± 6.6%; P < 0.001) and in the diabetes and unknown subgroups. The corneal endothelial cell density reduction rate 3 months and 1 year after surgery was not significantly different between the intraocular mydriasis group and controls.
Conclusion: Intracameral injection of Mydrin-P appears to be effective and safe for dilating the pupil in cases with poor mydriasis after preoperative instillation of mydriatics.
© 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists.