Visual field of the ferret ( Mustela putorius furo ), rat ( Rattus norvegicus ), and tree shrew ( Tupaia belangeri )

To describe the visual field of three common model species in vision science to understand the organization of their visual perceptual experience and contribute to continued studies of visual processing. Visual fields were measured using an ophthalmoscopic reflex technique in four common ferrets, four albino rats, and six northern tree shrews. Animals were anesthetized to avoid stress and the midpoint between their eyes was centered inside a spherical space. A rotating perimetric arm was manipulated in 10° increments around the head. At each increment, direct ophthalmoscopy was used to visualize limits of the retinal reflex for each eye, the overlap being the binocular visual field. Mean binocularity in the horizontal plane was 63.7 ± 5.1°, 79.1 ± 7.4°, and 53.6 ± 12.0° in the ferret, rat, and shrew, respectively. Maximum mean binocularity was 69.0 ± 1.6° in the ferret, 90.0 ± 3.1° in the rat, and 53.6 ± 12.2° in the shrew, located at 10° above, 40° above, and at the horizontal plane, respectively. Binocularity extended to 160°, 200°, and 180° in the sagittal plane in the ferret, rat, and shrew, respectively, from at least below the nose to above the head in all animals. Establishing the extent of the visual field accessible to the retina provides insight into the egocentric perceptual experience of animals. In describing the visual field, we provide a reference for the representation of the visual space in different cortical and retinal regions, many of which represent specific subregions of the visual field.