Definition of Cataract: "Any congenital or acquired opacity in the lens capsule or substance,irrespective of the effect on vision,is a cataract." Cataract is a relative severe disease which can cause blindness.It may scare the patients.So,it is better not use it in the case that the lens opacity would NOT affect the vision of the patients. Use“lens opacity”instead. Cerulean CataractDefinition of Cataract: Cataract is a relative severe disease which can cause blindness. It may scare the patients. So, it is better not use it in the case that the lens opacity would NOT affect the vision of the patients. Use “lens opacity” instead. “Any congenital or acquired opacity in the lens capsule or substance, irrespective of the effect on vision, is a cataract.” Cerulean Cataract