Search results
Results from the WOW.Com Content Network
The sclera's blood vessels are mainly on the surface. Along with the vessels of the conjunctiva (which is a thin layer covering the sclera), those in the episclera render the inflamed eye bright red. [6] In many vertebrates, the sclera is reinforced with plates of cartilage or bone, together forming a circular structure called the sclerotic ring.
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 this. The front part is also called the anterior segment of the eye.
Scleral lenses may be used to improve vision and reduce pain and light sensitivity for people with a growing number of disorders or injuries to the eye, such as severe dry eye syndrome, microphthalmia, keratoconus, [1] corneal ectasia, Stevens–Johnson syndrome, Sjögren's syndrome, [2] aniridia, neurotrophic keratitis (anesthetic corneas), complications post-LASIK, higher-order aberrations ...
The compound eyes of the arthropods are composed of many simple facets which, depending on anatomical detail, may give either a single pixelated image or multiple images per eye. Each sensor has its own lens and photosensitive cell(s). Some eyes have up to 28,000 such sensors arranged hexagonally, which can give a full 360° field of vision.
Later procedures focused on modifying the axial length of the eye, by preventing elongation and staphyloma progression by placing grafts over the posterior part of the eye. In 1930, Shevelev proposed the idea of transplantation of fascia lata for sclera reinforcement. [8] Curtin promoted the use of donor-sclera grafting for reinforcement. [9]
Sclera; 12. Conjunctiva, 13. Uvea with 14. Iris, 15. Ciliary body. The anterior segment or anterior cavity [1] is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. [2] [3] Within the anterior segment are two fluid-filled spaces:
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.
Scleral translucency following recurrent scleritis. 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