Sclera However, acid burns, even severe ones, seldom result in loss of the eye. Alkali burns, on the other hand, such as those resulting from exposure to ammonium hydroxide or ammonium chloride or other chemicals with a pH above 11.5, will cause cellular tissue in the sclera to saponify and should be considered medical emergencies requiring immediate treatment. Yellowing of the sclera is a visual symptom of jaundice. In very rare but severe cases of kidney failure and liver failure, the sclera may turn black. Sclera The sclera, also known as the white of the eye, is the opaque, fibrous, protective,
Arthropod eye curved surface. Later designs used graduating lens sizes. The third eye morphology of trilobites, called the abathochroal, was found only within the Eodiscina. This morphology consisted of up to 70 much smaller lenses. The cornea separated each lens, and the sclera on each lens terminated on top of each cornea. The eye morphology of trilobites is useful for determining their mode of life, and can function as palaeoenvironmental indicators. The horseshoe crab has traditionally been used in investigations into the eye, because it has relatively large ommatidia with large nerve fibres (making them easy to experiment on). It also falls