Tear-deficient and evaporative dry eye syndromes of the horse.

This research article discusses two main categories of dry eye conditions in horses: tear-deficient dry eye and evaporative dry eye. It describes the methods for detecting and examining these conditions, highlighting the potential for overlap between the two, and points to the need for more detailed examination of factors influencing ocular surface health in horses.

Dry Eye Conditions in Horses

• The study elucidates two major categories of dry eye diseases in horses, namely tear-deficient dry eye (also known as keratoconjunctivitis sicca) and evaporative dry eye.
• These two conditions may have specific and overlapping symptoms, depending on the degree and type of manifestation.
• They stress careful ophthalmological examination on horses to diagnose these conditions accurately and treat them promptly.

Detection and Examination of Dry Eye Conditions

• An extensive examination method is proposed. This includes examining the eyelid margins, the inner and outer surfaces of the upper and lower eyelids, along with assessing the horse’s blinking and movement of the third eyelid.
• The research recommends specific testing procedures of tear production, assessment of corneal sensitivity, and slit-lamp examination of the ocular surface before and after the application of fluorescein dye.
• In several cases, Rose Bengal dye application is also suggested as it can help assess the degree of dryness and quantify the damage to the ocular surface.

Potential Complications and Future Perspectives

• Facial nerve paresis, a condition that causes partial loss of voluntary muscle movement, is indicated as a possible complicating factor that might exacerbate the dry eye condition in some horses.
• The paper calls for further exploration into evaporative dry eye disease, especially due to its potential role as a contributing factor in ocular surface diseases such as keratomycosis (a fungal infection of the cornea).
• It underlines the need for further research into the factors that influence the health of the ocular surface in horses to improve diagnosis and treatment protocols for dry eye conditions.