The proteins are arranged to let light pass through and focus on the retina. Sometimes some of these proteins clump together. This can start to cloud small areas of the lens, blocking some light from reaching the retina and interfering with vision. This is a cataract. Cataracts can be categorized as congenital or acquired.
Congenital cataracts are ones that are present in the lens at birth.
They can vary in severity from severe, requiring removal within the first few months of life to preserve vision, to extremely mild, never requiring removal. Acquired cataracts are not present at birth. Instead, they develop in adulthood, as a person ages, or as a reaction to certain medications or disease. The genetic type of congenital cataract is often inherited in an autosomal dominant fashion. This means that they are caused by an abnormality in only one of a pair of genes.