Corneal sensation after topical anesthesia.

PURPOSE

To compare the topical effects of tetracaine, lidocaine, and bupivacaine on corneal sensitivity in normal eyes.

METHODS

Corneal touch sensitivity was measured with a Cochet-Bonnet anesthesiometer before and at 2.5-minute intervals after instillation of the anesthetic agent, until baseline levels had been reestablished. Seventeen healthy volunteers were randomized into five groups. Group 1 included 0.5% tetracaine (n = 6); group 2, 4% lidocaine (n = 8); group 3, 0.75% bupivacaine (n = 8); group 4, 0.5% tetracaine + 4% lidocaine (n = 5); and group 5, 0.5% tetracaine + 0.75% bupivacaine (n = 7).

RESULTS

The duration of anesthesia showed no differences between groups 1, 3, and 5. Although there was no difference between groups 2 and 4, both groups demonstrated significantly longer effects than groups 1, 3, and 5 (p < 0.005).

CONCLUSION

The application of 4% lidocaine results in a significantly prolonged topical anesthetic effect when compared with tetracaine and bupivacaine.