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The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. [1] [2] In humans, the refractive power of the cornea is approximately 43 dioptres. [3]
The cornea is transparent and more curved and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 11.5 mm (0.45 in) in diameter, and 0.5 mm (500 μm) in thickness near its centre.
A refractive cornea type eye of a human. The cornea is the clear domed part covering the anterior chamber of the eye. In the eyes of most mammals, birds, reptiles, and most other terrestrial vertebrates (along with spiders and some insect larvae) the vitreous fluid has a higher refractive index than the air. In general, the lens is not spherical.
Together, the cornea and lens refract light into a small image and shine it on the retina. The retina transduces this image into electrical pulses using rods and cones. The optic nerve then carries these pulses through the optic canal. Upon reaching the optic chiasm the nerve fibers decussate (left becomes right). The fibers then branch and ...
The eyelids close or blink voluntarily and involuntarily to protect the eye from foreign bodies, and keep the surface of the cornea moist. The upper and lower human eyelids feature a set of eyelashes which grow in up to 6 rows along each eyelid margin, and serve to heighten the protection of the eye from dust and foreign debris, as well as from ...
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Rufus was the first to recognise a two-chambered eye, with one chamber from cornea to lens (filled with water), the other from lens to retina (filled with a substance resembling egg whites). Celsus the Greek philosopher of the second century AD gave a detailed description of cataract surgery by the couching method.
Dr. Ming Wang grew up wanting to be a doctor — and that’s because he comes from a long line of medical professionals. “Five generations (of doctors) since the Qing Dynasty,” Wang tells ...