Cornea
Cornea - the transparent part of the forward side of an eye which coats an iris, a pupil, and the forward cabinet of an eye, providing the most part of the optical power of an eye. Together with a lens, the cornea refracts light and, as a result helps an eye to concentrate. The cornea promotes more than the full refraction, than the lens does, but, whereas curvature of a lens can be fitted to "attune" the center, curvature of a cornea is fixed. The cornea has nervous terminations, sensitive to concern, temperature and chemical substances; easy the cornea forces an unintentional reflex to close an eyelid. As the transparency has a principal value, the cornea does not have blood vessels; it gains nutrients through diffusion from a disrupture fluid in an outer side and a watery moisture in an interior part and also from neurotrophins, a nerve delivered by stratums which raise it. People, at a cornea have diameter approximately 12 mm and a thickness of 0.5 mm - 0.7 mm at center and 1.0 mm - 1.2 mm in periphery. A transparency, avascularity, and the immunologic privilege do a cornea by very special tissue.
At people, a cornea refractivity - approximately 45 diopters, about three quarters of the full power of an eye.
The medical terms bound with rogovitsoj it is frequent, begin with "kerat-".
The surgical procedures involving a cornea
Various refracting eye methods of surgery change the cornea shape to reduce Condition for points or otherwise to refine refracting state of an eye. In the methods used today, cornea parts leave with lasers.
If the corneal stroma has developed opaque maculae known as leukomas, a cornea of the donor died can be replaced. As is a few blood vessels in a cornea, is also a few problems with tearing away of a new cornea.
In development there are also synthetic corneas. The majority - primely plastic loose leaves, but is also some made of a plasty which encourage an eye tissue to be transmuted into a synthetic cornea, doing its full replacement.
The conservative procedures involving a cornea
Orthokeratology - a method, using, spetsializiroval firm or firm gazovo-water-permeable contact lenses to change a cornea to refine refracting state of an eye or to reduce Condition for oculars and contact lenses.
Types of corneal surgery
The corneal surgery includes the majority of refracting surgeries just as the following:
• Corneal transplantation of tissues, is used to remove the turbid/pathologically changed cornea and to exchange it clear donor rogovitsoj.
• Through keratoplasty (PK)
• Phototherapeutic keratectomy (PTK)
• Pterygium ex-concession
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