While scleral lenses are fit through a system of trial and error with prefabricated lenses, casted lenses are made from an impression of the ocular surface just like a prosthetic eye. Instead of using a series of standardized curvatures as with scleral lenses, casted lenses are generated to exactly match the unique irregularities of the individual eye. Because of the precise nature of the back surface fit, high-quality and individualized optics can be placed on the front surface of the device creating exactly what is needed.