Differences in ocular parameters between diurnal and nocturnal raptors

Area of Science:

• Ophthalmology
• Veterinary Medicine
• Comparative Biology

Background:

• Establishing normal ocular parameters is crucial for diagnosing ophthalmic diseases in raptors.
• Previous studies have not comprehensively compared ocular metrics between diurnal and nocturnal raptor species.

Purpose of the Study:

• To establish and compare normal ocular parameters in diurnal and nocturnal raptor groups.
• To assess the reliability of different measurement techniques for ocular parameters.

Main Methods:

• Ophthalmically normal raptors (n=88) from 17 species were studied.
• Tear production was measured using Schirmer tear test (STT) and phenol red thread test (PRTT).
• Applanation tonometry, ultrasonography (axial length, mediolateral axis, vitreous body, pecten length), and conjunctival cultures were performed.

Main Results:

• Tear production was significantly lower in nocturnal species (P < 0.001).
• Vitreous body and pecten length were significantly longer in diurnal species (P < 0.001 and P = 0.021, respectively).
• No significant differences were found in intraocular pressure, axial length, or mediolateral axis between diurnal and nocturnal groups.

Conclusions:

• Both PRTT and STT are valid for tear production measurement, but species-specific baselines are necessary.
• The diurnal/nocturnal classification has limited significance for baseline ocular parameters in raptors due to significant interspecies variation.