Cysteamine works by reducing the amount of cystine (an amino acid) in the body. Cysteamine is used in people with nephropathic cystinosis (NEF-roe-PATH-ik SIS-tin-OH-sis), a rare genetic condition that causes a build-up of cystine in the kidneys and other organs. Too much cystine can cause kidney failure or other medical problems. Cysteamine ophthalmic (for the eyes) is used to keep cystine crystals from building up in the cornea (surface of the eye). Cysteamine ophthalmic may also be used for purposes not listed in this medication guide.
Cystaran eye drops are used by doctors to treat cystine crystal build up in the cornea of a patient. This is only done on the front part of the eye. Cystaran is prescribed to patients with cystinosis, which is a inherited condition that mainly causes the accumulation of the amino acid cystine within the cells, forming crystals that eventually build up and cause great damage to the eye. This medication mainly works by removing the extra cystine.