Prosthetic eye lens. View of a gloved hand using a pair of forceps to hold a prosthetic crystalline eye lens. This is used to replace damaged eye lenses and is used in cataract surgery. A cataract is a condition where the lens of the eye becomes opaque. This can be because of infection, damage to the eye or may be hereditary. In extreme cases the lens must be replaced by an artificial lens. The implant usually provides excellent distance vision without glasses, but glasses are usually necessary for close vision. The gloves are used to maintain sterile conditions.