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The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is 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. Eye color is defined by the iris.
The right consensual reflex is intact. When the left eye is stimulated by light, the right pupil constricts, because the afferent limb on the left and the efferent limb on the right are both intact. The right direct reflex is intact. When light is shone into right eye, right pupil constricts.
Dilation and constriction of the pupil. The eye includes a lens similar to lenses found in optical instruments such as cameras and the same physics principles can be applied. The pupil of the human eye is its aperture; the iris is the diaphragm that serves as the aperture stop.
With this simple geometrical similarity, based on the laws of optics, the eye functions as a transducer, as does a CCD camera. In the visual system, retinal , technically called retinene 1 or "retinaldehyde", is a light-sensitive molecule found in the rods and cones of the retina .
The pupil constricts when the iris sphincter muscle is stimulated and contracts In humans, it functions to constrict the pupil in bright light ( pupillary light reflex ) or during accommodation . [ citation needed ] In lower animals, the muscle cells themselves are photosensitive causing iris action without brain input.
In many cases, only one eye is affected and the person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye. People may also engage in "eccentric viewing" using peripheral vision to compensate for central vision loss characteristic in genetic, toxic, or nutritional optic neuropathy.
The pupil function or aperture function describes how a light wave is affected upon transmission through an optical imaging system such as a camera, microscope, or the human eye. More specifically, it is a complex function of the position in the pupil [ 1 ] or aperture (often an iris ) that indicates the relative change in amplitude and phase ...
Aniridia is a condition characterized by the absence or near absence of the iris, the colored, muscular ring in the eye that controls the size of the pupil and regulates the amount of light entering the eye. This absence results in a primarily black appearance of the central eye.