Cataracts are the opacification of the lens of the eye, the natural lens located inside the eye and responsible, along with the cornea, for focusing images.

The lens can undergo a progressive process of opacification that typically becomes more pronounced as the years go by, but can also occur at a young age or even at birth (congenital cataract).

The treatment of choice is surgical, by phacoemulsification surgery and implantation of an artificial intraocular lens. Phacoemulsification consists of the following steps: corneal-level incision of just 2.2 to 2.4 millimeters, circular opening in its anterior capsule, fragmentation and aspiration of the lens through an apparatus just over 1 millimeter in diameter. This creates a kind of bag consisting of the lens capsule within which an intraocular lens is placed.