EXPRESS: The Impact of General Anesthesia on Feline Aqueous Tear Production and the Feline Corneal Epithelium

Objective Identify the prevalence of corneal injury in cats undergoing general anesthesia (GA) while receiving prophylactic ocular lubrication, identify risk factors for corneal injury, and quantify the effect of GA on tear production in cats. Materials and Methods Forty-two cats undergoing GA for non-ophthalmic procedures were included. Prior to GA, an ocular exam including a Schirmer Tear Test-I (STT) and fluorescein stain (FS) was performed. Prophylactic lubrication was administered at the time of anesthetic induction and repeated every 15 minutes until extubation. One hour after extubation, STT and FS were performed and repeated hourly for four hours. A Shapiro-Wilk and paired t-test compared STT results before and after GA. Logistic regression was used to analyze corneal injury and possible risk factors for corneal injury. Results No cats developed FS uptake consistent with corneal ulceration. Fourteen cats and 23 eyes (27.4% of eyes) developed corneal erosion at all time points. There was a significant decrease in tear production at all four time points post-GA. Premedication opioid choice and corneal exposure were identified as significant risk factors for corneal injury. Conclusions Corneal ulceration did not develop post-GA in this study. There is a significant decrease in tear production in cats for at least four hours after GA. Cats appear to have a higher prevalence of corneal injury post-GA compared to dogs. Frequent eye lubrication is recommended for feline patients during and after GA.