Natural aging processes and other factors (e.g. family, injury, diabetes, eye surgery) can lead to clouding of the lens, colloquially known as cataract. The cloudiness reduces visual acuity and contrast vision, and colours are perceived differently. Vision is "foggy". The only way to treat cataracts is surgery. This is one of the most common medical interventions worldwide and has developed into a very safe technology over the last decades, which allows for optimal visual acuity and a gain in quality of life.

To be able to aspirate the lens, a circular opening of the lens capsule is first performed manually. The lens is then divided manually and crushed and aspirated with ultrasound. The foldable artificial lens is placed in the now empty capsular bag, where it remains for a lifetime.