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Some skates and rays have crescent shaped pupils, [16] gecko pupils range from circular, to a slit, to a series of pinholes, [17] and the cuttlefish pupil is a smoothly curving W shape. Although human pupils are normally circular, abnormalities like colobomas can result in unusual pupil shapes, such as teardrop, keyhole or oval pupil shapes.
When the pupil takes on the shape of a tadpole, the condition is called tadpole pupil. Tadpole pupil, also known as episodic segmental iris mydriasis, is an ocular condition where the muscles of the iris begin to spasm, causing the elongation, or lengthening, of parts of the iris. [ 1] These spasms can affect any segment, or portion, of the ...
Anisocoria is a common condition, defined by a difference of 0.4 mm or more between the sizes of the pupils of the eyes. [2] Anisocoria has various causes: [3] Physiological anisocoria: About 20% of population has a slight difference in pupil size which is known as physiological anisocoria. In this condition, the difference between pupils is ...
The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds, responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
The pupil of the human eye can range in size from 2 mm to over 8 mm to adapt to the environment The human eye can detect a luminance from 10 −6 cd/m 2 , or one millionth (0.000001) of a candela per square meter to 10 8 cd/m 2 or one hundred million (100,000,000) candelas per square meter.
Another mechanism regulates focusing chemically and independently of these two, by controlling growth of the eye and maintaining focal length. In addition, the pupil shape can be used to predict the focal system being utilized. A slit pupil can indicate the common multifocal system, while a circular pupil usually specifies a monofocal system.
Polycoria. 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.
Light enters the eye at the cornea, passing through the pupil to reach the lens. Most fish species seem to have a fixed pupil size, but elasmobranches (like sharks and rays) have a muscular iris which allows pupil diameter to be adjusted. Pupil shape varies, and may be e.g. circular or slit-like. [5]