Human eye of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock. The eye is not shaped like a perfect sphere, rather it is a fused two-piece unit, composed of the anterior segment and the posterior segment. The anterior segment is made up of the cornea, iris and lens. 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 (0.3 in) in diameter, and 1/2 mm (500
Eye bank diseases such as HIV, hepatitis B, hepatitis C, human cytomegalovirus, syphilis, and sometimes others. The blood type is also tested, although corneas do not receive any blood supply and match typing is not necessary for transplantation. If the entire eye is enucleated during the original recovery, then the cornea and part of the sclera are removed and placed in a container with preservation medium, and the sclera is cleaned and then preserved in alcohol. The corneas are visually examined and evaluated underneath a slit-lamp, and the number of endothelial cells are counted underneath a specular microscope. The Eye Bank Association