ADVICE

Keratoconjunctivitis sicca (dry eye)

Dry eye is a common eye disease of dogs. It occurs when insufficient tears (which are essential to keep the eye moist and healthy) are produced from the tear glands and is diagnosed by measuring the tear production using a Schirmer Tear Test (STT).

• Normal STT: 15-25 mm/minute
• Suspicious STT: 10-15 mm/minute
• Low STT: 10 mm/minute

In most cases, both eyes are affected.

What are the signs of dry eye?

Common signs of dry eye include:

• Recurrent conjunctivitis
• A sticky grey/white/green discharge from one or both eyes
• Clouding or dullness of the surface of the eye with neovascularisation and pigmentation
• Discomfort (blinking more, rubbing, keeping the eye half closed).

What are the treatment options for dry eye?

Dry eye cannot be cured, but it can be managed well with lifelong medications. Treatment goals are to remove the pain and maintain vision. Treatment options usually include the following:

• Medication to stimulate tear production – In most cases, the first-line treatment is cyclosporine eye ointment (Optimmune). Optimmune treats the underlying cause of dry eye (destruction of the tear glands by the body's immune system) and as such is the best treatment in mild to moderate cases. It is usually very effective, but it needs to be given twice daily every day, and lifelong treatment is usually required. If Optimmune is ineffective, a different eye medication called tacrolimus may be effective
• Medication to replace the tears – These include drops, gels and ointments to keep the surface of the eye moist and prevent evaporation of tears. These do not treat the underlying cause, but instead help to replace the tears that are not being produced
• Antibiotics – Corneal ulcers and bacterial infections occur quite commonly in dogs with dry eye and so antibiotic eye drops may be prescribed from time to time
• Surgery – Parotid duct transposition (PDT) can be performed should the above medication prove unsuccessful. The surgery involves moving a salivary duct from its usual opening in the mouth to inside the lower eyelid. Saliva is then secreted onto the surface of the eye and acts to 'mimic' tears and keep the surface of the eye moist. Even after surgery, lifelong management with eye medications may still be needed to treat any complications that can occasionally be caused by saliva being present in the eye instead of tears.

Whatever treatment is advised, it will usually be needed for the duration of the dog’s life and regular visits to the ophthalmologist or your own veterinary surgeon will still be needed. During these visits, the health of the eye will be checked, tear production will be reassessed and any side effects of the treatment will be monitored.