The raptor visual system: An update.

CONCLUSIONS: Birds of prey are endowed with the highest VA of the animal kingdom. However most of the works study one individual or a small group of individuals, and the methodology is heterogeneous. The most studied bird is the Peregrine falcon (Falco peregrinus), with an estimated VA of 140 cycles/degree. Some eagles are endowed with similar VA. The tubular shape of the eye, the large pupil, and a high density of photoreceptors make this extraordinary VA possible. In some species, histology and optic coherence tomography demonstrate the presence of 2foveas. The nasal fovea (deep fovea) has higher VA. Nevertheless, the exact function of each fovea is unknown. The vitreous contained in the deep fovea could behave as a third lens, adding some magnification to the optic system.
PMID: 28209509 [PubMed - as supplied by publisher]

Source: Archivos de la Sociedad Espanola de Oftalmologia - February 19, 2017 Category: Opthalmology Tags: Arch Soc Esp Oftalmol Source Type: research