Photography-based method for assessing fluorescein clearance test in dogs

Area of Science:

• Veterinary Ophthalmology
• Ocular Surface Disease
• Diagnostic Imaging

Background:

• The fluorescein clearance test (FCT) is crucial for evaluating tear film dynamics.
• Assessing FCT in dogs traditionally requires specialized equipment.
• A practical, cost-effective method for canine FCT is needed.

Purpose of the Study:

• To develop an inexpensive, photography-based method for canine fluorescein clearance testing (FCT).
• To evaluate the retention time of one versus two drops of fluorescein on the canine ocular surface.
• To establish the reliability of this new FCT method in dogs.

Main Methods:

• Developed a photography and ImageJ software analysis method for FCT.
• Administered one or two drops of fluorescein to the eyes of eight German Shepherd dogs under topical anesthesia.
• Collected fluorescein-impregnated Schirmer strips at timed intervals (10 min to 72 hours) for imaging and analysis.

Main Results:

• The photography-based FCT demonstrated high repeatability and reproducibility (CV ≤ 2.75%).
• Two fluorescein drops resulted in significantly greater fluorescein uptake area and intensity at 30-40 minutes compared to one drop.
• Residual fluorescein was <5% at 60 min (1 drop) and 90 min (2 drops).

Conclusions:

• Photography-based FCT is a practical and reliable diagnostic tool for veterinary medicine.
• Two fluorescein drops enhance retention on the anesthetized canine ocular surface compared to a single drop.
• The fluorescein clearance time for a single drop in dolichocephalic dogs is approximately 60 minutes.