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Polycoria is a pathological condition of the eye characterized by more than one pupillary opening in the iris. [1] It may be congenital or result from a disease affecting the iris. [1] It results in decreased function of the iris and pupil, affecting the physical eye and visualization.
In very bright light, the slit-like pupil closes very narrowly over the eye, reducing the amount of light on the sensitive retina, and improving depth of field. Big cats have pupils that contract to a round point. Variation in color of cats' eyes in flash photographs is largely due to the reflection of the flash by the tapetum. A closeup of a ...
A mydriatic pupil will remain excessively large even in a bright environment. The excitation of the radial fibres of the iris which increases the pupillary aperture is referred to as a mydriasis. More generally, mydriasis also refers to the natural dilation of pupils, for instance in low light conditions or under sympathetic stimulation.
Some white cat fancies (e.g., white Turkish Angora or white Turkish Van cats) may show striking heterochromia, with the most common pattern being one uniformly blue, the other copper, orange, yellow, or green. [12] Striking variation within the same iris is also common in some animals, and is the norm in some species.
Light falling in one eye affects the diameter of the pupils in both eyes. One can easily see this by looking at a friend's eye while he or she closes the other: when the other eye is open, the pupil of the first eye is small; when the other eye is closed, the pupil of the first eye is large. Accommodation and vergence. Accommodation is the ...
Cats' eyes are largely similar to ours but with some fascinating differences, and one thing they have that we don't is a third, inner eyelid, called the nictitating membrane.
The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. [1] It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil.
Light entering the eye strikes three different photoreceptors in the retina: the familiar rods and cones used in image forming and the more newly discovered photosensitive ganglion cells. The ganglion cells give information about ambient light levels, and react sluggishly compared to the rods and cones.