Dry eye can easily be overlooked. Always do a STT (schirmer tear test) in all cases of ocular discharge, conjunctivitis and corneal disease.
The normal STT for a dog should be > 15 mm wetting/minute.
Management of Dry eye
There are many brands on the market, and in most cases it does not matter what type you use. In some cases preservative free tears are needed if the eye is irritated by normal tear drops. Artificial Tears need to be used often in severe dry eye cases, every 1 to 2 hours. Use tears to clean out all the mucoid discharge before using the active drugs. Mucky discharge can stop these medications from reaching the tear producing glands.
Optimmune (Cyclosporin 0.2%, Schering Plough)
Optimmune is the treatment of choice for dry eye. In early dry cases ie those less than 6 months duration, and in those with an initial STT >5 mm/min, successful treatment can be expected in more than 90% of cases. If the initial STT is less than 5mm/min, use the Optimmune TID, otherwise start the Optimmune BID. Tell your clients to use the Optimmune sparingly, i.e a rice grain sized amount. Optimmune will need to be used for 4 to 6 weeks before a response can be expected. Recheck the STT at this time. Most dogs with KCS will require long term Optimmune. Cyclosporin drops and Tacrolimus can be considered in cases that do not respond to Optimmune. Recent work is suggesting that refractory dry eye cases can be improved by using a combination of Cyclosporin and Tacrolimus eye drops. dry eye 1
These last longer than drops and help reduce corneal exposure. However artificial tears provide the best nutrition to the cornea, so liquid tears are important in managing dry eye. We tend to use the ointments at night time and during the day when the owner is unable to put in the medications. If the dry cornea is not healthy we use Viscotears gel and or Refresh Night Gel to help coat the cornea. If the cornea is healthy and there is no risk of ulceration then cortisone ointments are preferred as they help to reduce the associated vascular keratitis.