Retinal Morphological Characterization of Collared Scops Owl (Otus lettia) Using Optical Coherence Tomography and Histological Techniques.

Abstract

OBJECTIVE: To establish normative retinal imaging and measurement data for the Collared Scops Owl (Otus lettia), a nocturnal raptor clinically free of systemic and ophthalmological disorders, using optical coherence tomography and histopathology. ANIMAL STUDIED: Ten eyes from 6 Collared Scops Owls (Otus lettia) were included in the study. PROCEDURES: As part of the standard pre-release assessment, ocular reflex tests and basic ophthalmic examinations were performed prior to anesthesia induction. Routine X-ray and blood work were then conducted under general anesthesia, followed by OCT imaging for high-resolution retinal analysis. Parameters assessed included the pecten-foveal distance, foveal width, foveal depth, total retinal thickness (TR), neurosensory retinal thickness (NS), and ganglion cell complex thickness (GCC). Retinal images acquired through OCT were compared with corresponding histological sections to validate the findings and evaluate structural correlations. RESULTS: A single fovea was identified on the superior and temporal side of the pecten. The measured pecten-foveal distance was 5959.7 ± 147.45 μm (mean ± SD), while the foveal width and depth were 656 ± 41.81 μm and 65.3 ± 6.34 μm, respectively. The TR was 299.8 ± 23.08 μm, and the NS averaged 272.9 ± 21.94 μm; the GCC was 87.9 ± 6.24 μm. Histology revealed all retinal layers distinctly, which were well cross-referenced and correlated with OCT images. CONCLUSIONS: The morphology and measurement values of the retina in Collared Scops Owls were first established using OCT and histological analysis. These findings, which are fundamental to raptor ophthalmology, offer valuable support for medical care efforts and conservation.