[Histopathological study of the effect of preservative-free 1% lidocaine on rabbit lens epithelial cells].

Objective: To assess whether preservative-free 1% lidocaine is capable of loosing the junction between the rabbit lens epithelial cells (LECs) and between the cells and capsules and is capable of destroying the LECs, in order to provide scientific basis for pursuing safe and effective drugs to eliminate LECs in cataract surgery and to prevent capsular pacification.

Methods: Lens capsule specimens were collected from 29 rabbits (58 eyes) and divided into 3 groups: balanced salt solution (BSS) group (exposed to BSS for 1 minute), lidocaine group (exposed to preservative-free 1% lidocaine for 1 minute) and the control group. Specimens were stained with trypan blue and alizarin red. Photomicrographs of each capsule were taken to observe the viability of LECs and count the number of dead LECs. The histopathologic changes of LECs treated with lidocaine were evaluated by histological method and transmission electron microscope.

Results: The rate of dead LECs of the anterior and the equatorial lens capsules in control group was (1.51 +/- 0.39)%, and (1.52 +/- 0.32)%, respectively. The rate of dead LECs of the anterior and the equatorial lens capsules irrigated with BSS was (1.78 +/- 0.50)% and (1.77 +/- 0.47)%. The rate of dead LECs of the anterior and the equatorial lens capsules irrigated with preservative-free 1% lidocaine was (13.01 +/- 4.67)% and (9.59 +/- 3.35)%, respectively. The nested design ANOVA showed that the rate of dead LECs in the lidocaine group was greater than that in the control group or BSS group (P < 0.05), There was no significant difference in the number of dead cells between the anterior lens capsules and the equatorial lens capsules. After irrigated with lidocaine, cavities appeared ibetween the LECs and the capsule, cells detached from the capsule and showed vacuoles. The capsules of control group and BSS group showed a normal layer of LECs attached to the capsule. Under transmission electron microscope, in the lidocaine group, the junction between LECs and between the cell and the capsule were destroyed, many cells detached from the capsule and the rest arranged loosely. Some LECs dentes, and many vacuoles emerged, resulting in destruction of the cellular frame.

Conclusion: Preservative-free 1% lidocaine may loose the junction between the LECs and between the cells and capsules, resulting in degeneration and death of the LECs.