Читать книгу Essentials of Veterinary Ophthalmology - Kirk N. Gelatt - Страница 142

The extent of the visual field depends largely on placement of the orbits within the skull (Figure 2.17). Many mammalian prey, avian, and fish species have lateral eyes, providing almost 360° field of view. These animals have a small, frontal binocular field; two large peripheral monocular fields; and a small blind spot behind their head.

On the other hand, most primate and predator species have frontal eyes. In these species, most of the frontal visual field is covered by a binocular vision; there are two small, peripheral monocular fields and a large blind spot behind the skull. Therefore, enucleation will cause a cat, for example, to lose approximately 30° of one visual field, while in a horse the same procedure will cause a loss of about 145°.

Large (monocular) visual fields are typically associated with prey species that need to detect predators. This is why these species usually have a pupil and a visual streak whose shapes are aligned with the horizon, allowing them to identify predators and conspecifics.