The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and some other vertebrates, the whole sclera is white, contrasting with the coloured iris, but in most mammals, the visible part of the sclera matches the colour of the iris, so the white part does not normally show while other vertebrates have distinct colors for both of them. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, fatty deposits on the sclera can make it appear slightly yellow. People with dark skin can have naturally darkened sclerae, the result of melanin pigmentation.The human eye is relatively rare for having a pale sclera (relative to the iris). This makes it easier for one individual to identify where another individual is looking, and the cooperative eye hypothesis suggests this has evolved as a method of nonverbal communication. Structure
The sclera forms the posterior five-sixths of the connective tissue coat of the globe. It is continuous with the dura mater and the cornea, and maintains the shape of the globe, offering resistance to internal and external forces, and provides an attachment for the extraocular muscle insertions.
Fosdenopterin (or cyclic pyranopterin monophosphate, cPMP), sold under the brand name Nulibry, is a medication used to reduce the risk of death due to a rare genetic disease known as molybdenum cofactor deficiency type A.The most common side effects include complications related to the intravenous line, fever, respiratory infections, vomiting, gastroenteritis, and diarrhea.Fosdenopterin was approved for medical use in the United States in February 2021,  It is the first medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of molybdenum cofactor deficiency type A. and in the European Union in September 2022. Medical uses
Fosdenopterin is indicated to reduce the risk of mortality in people with molybdenum cofactor deficiency  (MoCD) type A. Mechanism of action
People with molybdenum cofactor deficiency type A cannot produce cyclic pyranopterin monophosphate (cPMP) in their body. Fosdenopterin is an intravenous medication that replaces the missing cPMP. cPMP is a precursor to molybdopterin, which is required for the enzyme activity of sulfite oxidase, xanthine dehydrogenase/oxidase and aldehyde oxidase. History
Fosdenopterin was developed at the German universities TU Braunschweig and the University of Cologne.The effectiveness of fosdenopterin for the treatment of MoCD-A was demonstrated in thirteen treated participants compared to eighteen matched, untreated participants. The participants treated with fosdenopterin had a survival rate of 84% at three years, compared to 55% for the untreated participants.The U.S. Food and Drug Administration (FDA) granted the application for fosdenopterin priority review, breakthrough therapy, and orphan drug designations along with a rare pediatric disease priority review voucher.