What is the main feature of qualitative KCS?

Qualitative Keratoconjunctivitis Sicca (KCS), or dry eye disease, primarily involves issues related to the quality of the tears produced, rather than the quantity. In this condition, there can be a deficiency in the lipid or mucin components of the tear film. These components are crucial for proper tear film stability and protection of the ocular surface. Lipid helps reduce evaporation of tears, while mucin plays a significant role in spreading the tear film evenly across the eye and facilitating adherence of tears to the corneal surface.

When there is a deficiency in lipid or mucin, despite possible normal or even slightly increased aqueous tear production, the tears cannot effectively lubricate and protect the eye. This leads to symptoms such as discomfort, redness, and potential corneal damage. In contrast, aqueous deficiency KCS would involve insufficient production of the aqueous layer itself, which is not the case in qualitative KCS. Hence, the identification of lipid or mucin deficiencies is key in diagnosing and managing this specific type of KCS. Careful assessment of the tear film and its individual components allows veterinarians to tailor treatments appropriate for the underlying cause of the dry eye condition.