Flash electroretinography in the bald eagle (Haliaeetus leucocephalus)

Area of Science:

• Comparative ophthalmology
• Avian physiology
• Retinal function assessment

Background:

• The electroretinogram (ERG) is a key diagnostic tool for retinal function.
• Limited normative ERG data exists for non-domesticated avian species like bald eagles.
• Understanding retinal function in bald eagles is crucial for their health management in captivity.

Purpose of the Study:

• To establish normative photopic and scotopic flash electroretinogram (fERG) values for adult captive bald eagles (Haliaeetus leucocephalus).
• To compare bald eagle fERG b-wave amplitudes with those of other species.
• To provide a clinical reference for fERG evaluations in bald eagles.

Main Methods:

• Performed complete ophthalmic examinations on 12 adult captive anesthetized bald eagles.
• Recorded photopic and scotopic flash electroretinograms (fERGs) using a standardized protocol.
• Analyzed and compared b-wave amplitudes across individuals and against existing species data.

Main Results:

• Bald eagles exhibited a notably higher b-wave amplitude in their fERGs compared to other species under similar testing conditions.
• The study established baseline fERG parameters for this species.
• Individual variations in b-wave amplitude were observed within the study population.

Conclusions:

• The elevated b-wave amplitude in bald eagles suggests unique adaptations in their retinal function.
• Normative fERG data can serve as a clinical reference for diagnosing retinal diseases in bald eagles.
• fERG evaluation can be a valuable preoperative screening tool for bald eagles undergoing procedures such as phacoemulsification.