Variability of Dry Eye Disease Following Removal of Lacrimal Glands in Rats.

Removal of lacrimal glands is used as a viable model of dry eye disease in rats. However, there is no uniform agreement on the disease severity following different variants of the procedure. The interpretation of the modeled dry eye disease also is biased by the interchangeable use of male and female rats. Therefore, this study seeks to define the features of dry eye disease following removal of the extraorbital lacrimal gland, with or without excision of the infraorbital lacrimal gland in male and female rats. The experiments were performed in 12-week-old female and male Sprague-Dawley rats. The baseline blink rate and fluorescein score were assessed. Subsequently, rats underwent isolated removal of the extraorbital gland, removal of the extraorbital gland combined with excision of the infraorbital gland, or a sham surgical procedure. The assessment of blink rate and fluorescein scores was repeated 28 days following surgery. Corneas were collected for histological analysis. We found that the blink rate and fluorescein score increased in all of the experimental groups, except the control group and the male rats that underwent isolated removal of the extraorbital lacrimal gland. Histopathological analysis revealed the thinning and edema of the epithelium in all groups, except the control group. These changes were most pronounced in female rats following combined removal of extraorbital and infraorbital lacrimal glands. In conclusion, severity of dry eye disease in the rat model is influenced by both gender and the extent of surgical removal of lacrimal glands. Combined excision of lacrimal glands in female rats produced the most severe pathological changes, whereas isolated excision of the extraorbital lacrimal gland in male rats led to the least severe changes.