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The sclera, [note 1] also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective outer layer of the eye containing mainly collagen and some crucial elastic fiber. [2] In the development of the embryo, the sclera is derived from the neural crest. [3]
The cooperative eye hypothesis is not the only one that has been proposed to explain the appearance of the human eye. Other hypotheses include the proposal that white sclerae are a sign of good health, useful in mate selection, or that eye visibility promotes altruistic behaviour by letting people know they are being watched. A study by the Max ...
Symptoms of scleritis include: [3] Redness of the sclera and conjunctiva, sometimes changing to a purple hue; Severe ocular pain, which may radiate to the temple or jaw. The pain is often described as deep or boring. Photophobia and tearing; Decrease in visual acuity, possibly leading to blindness; The pain of episcleritis is less severe than ...
Humans have two eyes, situated on the left and the right of the face. The eyes sit in bony cavities called the orbits, in the skull. There are six extraocular muscles that control eye movements. The front visible part of the eye is made up of the whitish sclera, a coloured iris, and the pupil. A thin layer called the conjunctiva sits on top of ...
The scleral ring or sclerotic ring is a hardened ring of plates, often derived from bone, that is found in the eyes of many animals in several groups of vertebrates. Some species of mammals, amphibians, and crocodilians lack scleral rings. [1] The ring is in the fibrous outer layer of the eye, called the sclera.
Red, itchy, or watery eyes are common symptoms of seasonal allergies, but they're also signs of pink eye, or conjunctivitis. Here’s how to tell the difference. Red, itchy, or watery eyes are ...
The conjunctiva is a thin membrane that covers the eye. When an allergen irritates the conjunctiva, common symptoms that occur in the eye include: ocular itching, eyelid swelling, tearing, photophobia, watery discharge, and foreign body sensation (with pain). [1] [3]
Other symptoms: Ant bites are typically painful and itchy. In addition to the bites, fire ants use their stinger to inject a venom called solenopsin, which causes a burning sensation, Frye says.