Has tear osmolarity been assessed in dogs with EDED?

• A. Yes
• B. No
• C. Only in select studies
• D. Not reported

Answer: (B)

Tear osmolarity is a marker of tear film balance, reflecting how concentrated the tear solutes are as the tear film becomes unstable or evaporates. In dogs with evaporative dry eye disease (EDED), the primary issue is a deficient lipid layer leading to increased evaporation, rather than a primary reduction in tear production. The literature on canine tear osmolarity has mainly focused on aqueous-deficient dry eye (keratoconjunctivitis sicca) and general tear film analyses, with little to no published data specifically measuring osmolarity in dogs diagnosed with EDED. Because no studies have reported tear osmolarity assessments in this particular condition, the current evidence does not show osmolarity data for EDED in dogs. If future research investigates this, osmolarity might be affected by the rate of evaporation and tear turnover, but at present there is no published information to confirm such findings.