A New Animal Model for Dry Eye

Abstract

Purpose: : Keratoconjunctivitis Sicca, or KCS, also known as dry eye, is an autoimmune disease of the conjunctiva due to decreased tear production that leads to irritation of the cornea. To study the disease and develop treatments, an animal model is necessary.

Methods: : A reliable and reproducible rat model for dry eye was developed by denervation of the trigeminal nerve through stereotaxic surgery by which radiofrequency was used to ablate at the V1-V2 junction. Corneal sensation was tested and tear production was measured in each eye prior to surgery and on the third and fifth day after surgery using phenol red tear threads.

Results: : All 22 animals treated with radiofrequency ablation lost corneal sensation and 20 (95%) animals displayed significantly less tear production in the experimental eye compared with the control eye. Prior to trigeminal denervation, baseline tear production in both eyes were similar ( 8.2 ± 3.2 mm vs 7.1 ± 2.7 mm, p > .08). However, tear production in the treated left eye was 44% less than the control eye on the third postoperative day (3.8 ± 2.1 mm vs. 6.8 ± 4.3 mm, P<0.01) and 46% on the fifth postoperative day (3.2 ± 1.7 mm vs. 5.9 ± 3.0 mm, p <0.01). A signed comparison signed test confirmed the significant difference in the reduction of tear production in the treated eye compared with the control eye (p<0.01). Histopathology of the conjunctiva and the cornea following trigeminal nerve ablation revealed a decrease of tear-producing goblet cells in the conjunctiva and a presence of inflammatory cells beneath the epithelium of the cornea.

Conclusions: : In conclusion, our animal model is reliable and accurate in displaying the physical signs of dry eye.

Keywords: conjunctiva • cornea: tears/tear film/dry eye