A comparison of pupil dilation and induction of corneal endothelial apoptosis by intracameral 1% lidocaine versus 1:100,000 epinephrine in rabbits

Purpose: The aim of this study was to evaluate the mydriatic effects of intracameral 1% lidocaine compared with 1:100,000 epinephrine and the effect on endothelial apoptosis in rabbits. Methods: Forty eyes of 20 New Zealand white rabbits were divided into 2 equal groups. In the first group, 1 eye was injected intracamerally with 1% lidocaine (lidocaine eyes) and the fellow eye with 1:100,000 epinephrine (epinephrine eyes). In the second group, 1 eye was injected with balanced salt solution (BSS eye) and the fellow eye was instilled with 1% tropicamide (mydriatics eye). Specular microscopy, transmission electron microscopy, scanning electron microscopy, and TdT-mediated dUTP nick-end labeling staining were performed 1 day postinjection. Results: Both the full-dilation time and pupil diameters of the lidocaine and epinephrine eyes were not significantly different (P>0.05). The endothelial cytoplasmic vacuolizations were increased and microprojections were diminished in the epinephrine eyes compared with the mydriatics, BSS, and lidocaine eyes (P<0.05). Apoptosis was demonstrated in only epinephrine eyes, with an index of 5%. Conclusions: In rabbits, the intracameral injections of preservative-free 1% lidocaine may be used as an adjunctive method with topical mydriatics in cataract surgery, as like 1:100,000 epinephrine. The intracameral 1% lidocaine may induce less microstructural alterations to the corneal endothelial cells than 1:100,000 epinephrine.