Abstract
Purpose:
To compare the anesthetic efficacy of lidocaine gel 2% and 5% on the ocular surface in healthy subjects.
Methods:
A prospective, randomized, double-blind study was carried out by spraying lidocaine gel, at a concentration of 2% or 5% in each eye, of a healthy reasearch group. The pain during instillation and conjunctival clamping were evaluated on the fifth and tenth minute after the application of the gel. The break-up time of the tear film was also measured and the degree of corneal conjunctival dyeing was rated according to the Oxford scale.
Results:
Eighty eyes of 40 patients were evaluated. The groups were similar in gender, with a mean age of 48 ± 16.26 years. The pain caused by instillation was found to be higher in the group using lidocaine gel 5 % (p = 0.092). Pain recorded at conjunctival clamping was lower in lidocaine 5 % (p = 0.564) in both the fifth the tenth minute (p <0.001). The majority of patients (80 %) had no corneal conjunctival dyeing. They were classified in grades I (16.25 %) and II (3.75 %) by the Oxford scale. The break-up time of the tear film was longer in the group using lidocaine gel 2 % (20.35 ± 7.37 seconds) compared to lidocaine 5 % (19.75 ± 7.00 seconds).
Conclusions:
Lidocaine gel 5 % showed an equal efficacy with longer lasting anesthetic effects in comparison to 2 %. There was no corneal toxicity at either concentration.