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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.
Keratoglobus is a very rare condition that causes corneal thinning primarily at the margins, resulting in a spherical, slightly enlarged eye. It may be genetically related to keratoconus. [19] Pellucid marginal degeneration causes thinning of a narrow (1–2 mm) band of the cornea, usually along the inferior corneal margin. It causes irregular ...
The main symptom is loss of vision, with colors appearing subtly washed out in the affected eye. A pale disc is characteristic of long-standing optic neuropathy. In many cases, only one eye is affected and a person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye.
An area termed the limbus connects the cornea and sclera. The iris is the pigmented circular structure concentrically surrounding the centre of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles.
The RNFL formed by the expansion of the fibers of the optic nerve; it is thickest near the optic disc, gradually diminishing toward the ora serrata.. As the nerve fibers pass through the lamina cribrosa sclerae they lose their medullary sheaths and are continued onward through the choroid and retina as simple axis-cylinders.
The artificial iris is a surgically implanted device made of thin, foldable, medical-grade silicone and is custom-sized and colored for each individual patient. The prosthetic iris is held in place by the anatomical structures of the eye or, if needed, by sutures. [7]
Iris Gonioscopy of the anterior chamber angle Anterior chamber angle cross-section imaged by an SD-OCT. The trabecular meshwork is an area of tissue in the eye located around the base of the cornea , near the ciliary body , and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the ...
Keratoconus, a progressive, noninflammatory, bilateral, asymmetric disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion. [ 2 ] Keratoglobus , a rare noninflammatory corneal thinning disorder, characterised by generalised thinning and globular protrusion of the cornea.