Arcus senilis (AS), also known as gerontoxon, arcus lipoides, arcus cornae, corneal arcus, arcus adiposus, or arcus cornealis, are rings in the peripheral cornea. It‘s usually caused by cholesterol deposits, so it may be a sign of high cholesterol. It is the most common peripheral corneal opacity, and is usually found in the elderly where it is considered a benign condition. When AS is found in patients less than 50 years old it is termed arcus juvenilis. The finding of arcus juvenilis in combination with hyperlipidemia in younger men represents an increased risk for cardiovascular disease. Pathophysiology
AS is caused by leakage of lipoproteins from limbal capillaries into the corneal stroma. Deposits have been found to consist mostly of low-density lipoprotein (LDL). Deposition of lipids into the cornea begins at the superior and inferior aspects, and progresses to encircle the entire peripheral cornea. The interior border of AS has a diffuse appearance, while the exterior border is well demarcated. The clear space between the exterior border and the limbus is called the interval of vogt.Bilateral AS is a benign finding in the elderly, but it can be associated with hyperlipidemia in patients less than 50 years old. Bilateral AS may also be caused by increased levels of free fatty acids in the circulation secondary to alcohol use.Unilateral AS can be associated with contralateral carotid artery stenosis or decreased intraocular pressure in the affected eye. As these are serious medical conditions, unilateral AS should be examined by a physician.
Usually the neurodevelopmental symptoms will decrease in later childhood.Phenylketonuria, also known as PKU, can induce neurodevelopmental problems and children with PKU require a strict diet to prevent intellectual disability and other disorders. In the maternal form of PKU, excessive maternal phenylalanine can be absorbed by the fetus even if the fetus has not inherited the disease. This can produce intellectual disability and other disorders. Nutrition
Nutrition disorders and nutritional deficits may cause neurodevelopmental disorders, such as spina bifida, and the rarely occurring anencephaly, both of which are neural tube defects with malformation and dysfunction of the nervous system and its supporting structures, leading to serious physical disability and emotional sequelae. The most common nutritional cause of neural tube defects is folic acid deficiency in the mother, a B vitamin usually found in fruits, vegetables, whole grains, and milk products. (Neural tube defects are also caused by medications and other environmental causes, many of which interfere with folate metabolism, thus they are considered to have multifactorial causes.) Another deficiency, iodine deficiency, produces a spectrum of neurodevelopmental disorders ranging from mild emotional disturbance to severe intellectual disability. (see also congenital iodine deficiency syndrome).Excesses in both maternal and infant diets may cause disorders as well, with foods or food supplements proving toxic in large amounts. For instance in 1973 K.L.