dry eyeservices

Dry eye in dogs - Keraconjunctivitis Sicca
Dry eye occurs in certain breeds of dogs which have a breed predisposition including the west highland terrier and the cavalier spaniel. In these breeds it is an autoimmune disease whereby the tear producing glands are inhibited from working by the dog producing antibodies against their own tissues. It may also occur in other breeds when the tear gland has been surgically removed from the third eyelid following prolapse of the gland. Dry eye may often be treated for long periods before a diagnosis is made. However diagnosis is very simple using a Schirmer tear test. ( STT ) Strips of paper are placed inside the lower eyelid for one minute allowing assessment of the amount of tears produced within that period by movement of dye along the strip. A normal Schirmer test should be over 20mm. In a severe case the STT can be zero. Anything less than 20mm is abnormal but may not produce symptoms until STT falls below 15mm.

Symptoms of dry eye are a recurrent mild conjunctival inflammation. As the condition worsens the cornea becomes dull due to lack of the reflective tear film. The cornea then becomes inflamed with migration of blood vessels into the cornea. Corneal ulcers may occur and an ulcer may be the first indication of the condition. Due to the lack of tears the oily secretions from glands in the eyelids tend to accumulate and these resemble pus giving the impression that this is a bacterial infection whereas any infection present is secondary to the dry eye.

Treatment of the condition is usually successful using drugs which will suppress the immune response. Topical steroid drops can be used with quite good effect. However long term treatment is required as the condition is incurable and long term use of steroids, even in topical drops, is not advisable. A newer immunosuppressive drug known as cyclosporine is the drug of choice. This usually needs to be applied twice daily for the rest of the dog’s life and unfortunately it can prove expensive. About 90% of autoimmune dry eyes will respond to cyclosporine. The cases which do not respond tend to be those that have a very low STT when diagnosed.

At the Animal Eye Centre we treat these cases for three months using a combination of cyclosporine, steroid drops and artificial tears. If after this time there is no improvement we have the option of surgical treatment. This involves transposing a duct carrying saliva into the mouth from its position inside the upper lip into a position between the lower eyelid and the third eyelid. This provides lubrication to the eye. Unfortunately saliva is not exactly the same as tears and can result in the deposition of salt crystal on the cornea in some cases. In addition, because dogs salivate when fed, these dogs also cry when fed. This can be a problem with saliva overflow causing scalding of the face. The surgery is beneficial in the majority of cases and will preserve vision in these eyes. Surgery is carried out at the Animal Eye Centre. It requires good magnification to identify the structures and suture them into the correct position. The alternative to surgery in these severe cases is very frequent application of artificial tears to the dry eye but they do need to applied every hour and this is not feasible for most owners.