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Rheum from a cat's eyes. Rheum (/ r uː m /; from Greek: ῥεῦμα rheuma 'a flowing, rheum') is a thin mucus naturally discharged from the eyes, nose, or mouth, often during sleep (contrast with mucopurulent discharge). [1] [2] [3] Rheum dries and gathers as a crust in the corners of the eyes or the mouth, on the eyelids, or under the nose. [3]
The idea that myopia was caused by the eye strain involved in reading or doing other work close to the eyes was a consistent theme for several centuries. [101] In Taiwan, faced with a staggering rise in the number of young military recruits needing glasses, the schools were told to give students' eyes a 10-minute break after every half-hour of ...
8.7% global prevalence in 2020 [ 2] Macular degeneration, also known as age-related macular degeneration ( AMD or ARMD ), is a medical condition which may result in blurred or no vision in the center of the visual field. [ 1] Early on there are often no symptoms. [ 1] Over time, however, some people experience a gradual worsening of vision that ...
Optics and vision. Vision of humans and other organisms depends on several organs such as the lens of the eye, and any vision correcting devices, which use optics to focus the image. The eyes of many animals contains a lens that focuses the light of its surroundings onto the retina of the eye. This lens is essential to producing clear images ...
The ocular immune system protects the eye from infection and regulates healing processes following injuries. The interior of the eye lacks lymph vessels but is highly vascularized, and many immune cells reside in the uvea, including mostly macrophages, dendritic cells, and mast cells. [ 1] These cells fight off intraocular infections, and ...
Adaptation (eye) In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher ...
As the human body ages, the vitreous often liquefies and may collapse. This is more likely to occur, and occurs much earlier, in eyes that are nearsighted (myopia). It can also occur after injuries to the eye or inflammation in the eye . The collagen fibres of the vitreous are held apart by electrical charges. With aging, these charges tend to ...
Uveitis. Uveitis ( / ˌjuːvi.aɪtɪs /) is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. [ 1] The uvea consists of the middle layer of pigmented vascular structures of the eye and includes the iris, ciliary body, and choroid.