Dry eye is the common name for Keratoconjunctivitis sicca (KCS), a disease affecting dogs, and less frequently, cats, where the eye(s) have either limited or no tear production. The cause is not known but infections and auto-immune diseases may play a role. Small breed older dogs are most at risk and some of the ‘flat-faced’ breeds are more susceptible because of their very large eyelid openings.
Any of the following symptoms may indicate a case of dry eye.
• An eye that looks dry
• Recurrent eye problems
• Ropy yellow discharge from the eye
• Red conjunctivae
We will initially conduct a Schirmer Tear Test (STT), which involves placing a small piece of absorbent paper over the lower lid. The dogs tear film moves down the paper and is measured after 60 seconds. In this time a dog should produce 15 mm of wetting of the paper, and cats 10 mm. Any less than this and your pet has dry eye. A full eye and body examination are also performed to check for underlying causes.
There are two phases to treatment of dry eye. Initially we will prescribe ‘artificial tears’ to try to replace the tears and keep the eye moist. These are applied up to 6 times a day, and thicker preparations are sometimes also used at night.
The second phase of treatment is to encourage the eyes to start naturally producing tears again. Medications such as Cyclosporin or Optimmune will usually significantly stimulate natural tear production, often returning tear production to normal. Occasionally other drugs may be added to the treatment plan to assist with tear production. Any other underlying or associated diseases would also be addressed.
Medications are not always effective. In cases that do not respond medically there are a number of surgical options. For dogs with large eyelid openings a procedure called paria closure can help reduce evaporation of tears. Sometimes we can reposition a salivary duct from the mouth to produce a tear film.
If your pet has dry eye but still has some tear production, the prognosis is better than if there is no tear production at all. Your dog will need regular STTs to monitor his response to therapy and we may suggest adjustments to medication based on the results. Unfortunately, we can often only control the disease, not fully cure it so treatment may have to be ongoing.