Pathological study on effects of preservative-free 1% lidocaine on lens epithelial cells of patients with age-related cataract

Abstract

To assess whether preservative-free 1% lidocaine is capable of destroying the LECs in age-related cataract (ARC) in order to provide scientific basis for pursuing safe and effective drugs to eliminate LECs in cataract surgery. Lens anterior capsule (LAC) specimens were collected from 75 patients (82 eyes) with age-related cataract (ARC), including forty males (44 eyes) and thirty-five females (38 eyes). The age range was 41 - 85 years, the mean age was 67.97 years. There were 34 cortical cataracts, 22 nuclear cataracts and 26 subcapsular cataracts. Capsule specimens were divided into 4 groups: balanced salt solution (BSS) group I and group II (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 to count the number of necrosis LECs. The pathologic changes of LECs were evaluated by histological methods (11 LAC, 22 pieces) as well as transmission and scanning electron microscopes (5 LAC, 10 pieces). In the control and BSS group I (23 LAC), one half of each capsule specimen was used for the control group and the other half was used for BSS group I. In lidocaine group and BSS group II (43 LAC), one half of each capsule specimen was used for lidocaine group and the other half was used for BSS group II. The rate of necrosis LECs of the anterior capsules in the control group and BSS group I was (56.19 +/- 2.71)% and (57.23 +/- 1.98)%, respectively. The rate of necrosis LECs of the capsules in lidocaine group and BSS group II was (99.86 +/- 8.22)% and (57.64 +/- 7.00)%, respectively. Matching t-test showed that the rate of necrosis LECs in lidocaine group was greater than that in the BSS group II (t = 27.6781, P = 0.0000). There was no significant difference in the number of necrosis LECs between the control group and BSS group I (t = 2.0693, P = 0.0505). There was also no significant difference between males and females; between different cataract, types and between varying age groups (P > 0.05). After irrigated with lidocaine, LECs showed vacuoles and detached from the capsule, and many cavities appeared between the LECs and the capsule. The capsules of BSS and control group showed a normal layer of LECs attached to the capsule. Under transmission and scanning electron microscopes, in lidocaine group, the junction between the LECs and between the cells and the capsule were destroyed; many cells detached from the capsule and the rest arranged loosely. Some LECs dented and many vacuoles emerged, resulting in destruction of the cellular structures. Preservative-free 1% lidocaine may loose the junction between LECs and between the cells and the capsule, and also destroy cellular structures, resulting in degeneration and necrosis of the LECs.