Schirmer Tear Test Value and Corneal Lesions’ Incidence during General Anesthesia for Non-Ophthalmic Surgery in Non-Brachycephalic Dogs: A Pilot Study Comparing Three Different Lubricant Eye Drop Formulations

Abstract

Aim of this blinded, prospective, randomized clinical study was to compare three different lubricant eye drops (LED) in healthy adult dogs undergoing general anaesthesia (GA) for non-ophthalmic surgery. Tear production rate was monitored by means of Schirmer tear test-1 (STT-1), and incidence of post-operative corneal abrasions/ulcerations was detected by corneal staining. A complete ophthalmic examination was performed before premedication, at extubation time and 24 h after GA in twenty-five non-brachycephalic dogs (fifty eyes) undergoing elective orthopaedic or spinal surgery procedures. Dogs were randomly allocated to one of three groups receiving as prophylactic LED either carmellose sodium (GC), or 1% hyaluronic acid (GH), or 0.25% hyaluronic acid (GL). In each eye STT-1 was repeated every hour during GA, before instilling one drop of the assigned LED. In all groups STT-1 values drastically decreased during GA, while 24 h later nine eyes (18%) had STT-1 values lower than 15 mm/minute. All of the three formulations tested were fully effective in preventing corneal ulceration (0% in all groups), while 10% of eyes reported superficial de-epithelialization. Fluorescein staining demonstrated that hourly prophylactic LED application prevented exposure keratopathy during general anesthesia in 90% of the eyes in non-brachycephalic dogs.

Dexmedetomidine and Tear Production: Evaluation in Dogs as Spontaneous Model for Ocular Surface Disorders

“…Sedation or general anesthesia can determine the perioperative dry eye syndrome, also known as exposure keratopathy (EK), as an ocular complication encountered in both human and veterinary medicine [ 8 , 17 , 22 ]. It is associated with the instability and hyperosmolarity of tear film and in severe cases, causes inflammation, neurosensory damage of the ocular surface and consequent development of permanent focal lesions of the cornea.…”

“…A marked decrease in tear production after induction of anesthesia has been reported in humans [ 12 , 13 , 14 , 15 ] and in dogs, using different anesthetic and sedative protocols [ 16 , 17 , 18 , 19 , 20 , 21 ]. The loss of corneal integrity resulting from perioperative dry eye can lead to corneal abrasions, which are the most common ocular complication in humans during general anesthesia for non-ophthalmic surgery [ 20 , 22 ]. Post-anesthesia corneal lesions have been reported also in dogs [ 17 , 20 , 21 ], cats [ 23 , 24 ] and horses [ 25 ].…”

Evaluation of Tear Production as Measured by Schirmer Test I in Dogs after Acepromazine and Acepromazine–Methadone Premedication

“…Many authors have reported that tear production in dogs is affected by tranquilizers, sedatives, opioids and general anesthetic drugs [ 2 , 3 , 4 , 8 , 16 ], although a variable effect on canine tear production was reported due to the inoculation of full μ-opioid receptor agonists, either alone or in association with sedatives or tranquilizers [ 2 , 16 , 17 , 18 ].…”

“…Perioperative dry eye can result in corneal abrasions due to the loss of corneal integrity. Exposure keratopathy, as a post-anesthesia complication, has been reported in dogs [ 8 , 9 , 10 , 11 ], cats [ 7 , 12 ] and horses [ 13 ].…”

A prospective, masked, randomized, controlled superiority study comparing the incidence of corneal injury following general anesthesia in dogs with two methods of corneal protection

“…[1][2][3] In dogs, the incidence of corneal injury is reported to be 1.9%-18.6% in eyes protected with ocular lubricant. 4,5,6 Corneal epithelial injury during GA arises from a combination of lagophthalmos due to relaxation of the orbicularis oculi muscle and reduced tear production secondary to drugs used for the GA. 1,7 The combined effect leads to corneal exposure and drying. Corneal injury can also be a result of direct trauma or chemical injury.…”