Tear Film Osmolarity in Horses With Bacterial Conjunctivitis

Area of Science:

• Ophthalmology
• Veterinary Medicine
• Biochemistry

Background:

• Conjunctivitis, an inflammation of the conjunctiva, can be viral or bacterial.
• Bacterial conjunctivitis is caused by pathogens like Staphylococcus and Streptococcus.
• Both forms are contagious, necessitating preventive measures.

Purpose of the Study:

• To determine tear film osmolality in horses with bacterial conjunctivitis.
• To establish preliminary reference ranges for tear film osmolality and electrolytes in healthy horses.

Main Methods:

• Tear samples were collected from 40 horses (healthy and with conjunctivitis).
• Samples were taken three times at 5-minute intervals and pooled.
• Osmolality and electrolyte concentrations (sodium, potassium, magnesium, calcium) were measured.

Main Results:

• Mean tear film osmolality was 283.51 (9.33) mmol/kg.
• Mean electrolyte concentrations: Na 134.75 (10) mmol/L, K 16.3 (5.77) mmol/L, Mg 3.48 (1.97) mmol/L, Ca 1.06 (0.42) mmol/L.
• Tear film sodium mirrored serum levels; tear film potassium was ~4.75x serum levels.

Conclusions:

• Tear film osmolality measurement is a non-invasive tool for assessing ocular conditions.
• Clinical utility requires integration with other parameters and further studies in horses with conjunctivitis.
• Developing these tools can enhance diagnostic accuracy and treatment strategies for equine eye diseases.