Evaluation of the phenol red thread tear test in falconiformes

Area of Science:

• Veterinary Ophthalmology
• Avian Medicine
• Ocular Surface Disease

Background:

• Falconiformes possess keen eyesight crucial for hunting and survival.
• Ocular diseases are frequently underdiagnosed in birds of prey due to limited diagnostic tools and data.
• Tear film deficiency is a known ocular issue in canines, but its prevalence in avian species is under-researched.

Purpose of the Study:

• To evaluate the phenol red thread (PRT) test as a viable alternative to the Schirmer tear test (STT) for assessing tear production in Falconiformes.
• To determine the reproducibility and practicality of the PRT test in avian subjects.

Main Methods:

• The phenol red thread (PRT) tear test was administered twice to each eye of 21 birds belonging to the genus Falco.
• Tear production was measured in millimeters per 15 seconds for each eye (OD and OS) and overall (OU).
• Reproducibility was assessed by correlating results from the first and second PRT tests.

Main Results:

• Mean PRT test values were OD=30.2±4.6 mm/15 s, OS=29.1±3.7 mm/15 s, and OU=30.6±4.2 mm/15 s.
• The PRT test demonstrated good reproducibility, with a strong positive correlation between repeated measurements.
• The PRT test yielded repeatable, easy-to-obtain, and easy-to-read results under standard conditions.

Conclusions:

• The phenol red thread (PRT) test is a repeatable and practical method for evaluating tear production in Falconiformes.
• This test offers a valuable, accessible diagnostic approach for ocular surface disease in birds of prey.
• Further research can utilize the PRT test to improve the diagnosis and management of eye conditions in avian species.