Cataracts are a degenerative process involving the crystalline lens (the eye's natural lens) that clouds vision and ends up affecting all of the elderly population. In the Western world, treatment involves brief, painless surgery with low anaesthetic risk and fast recovery, which gives very good results. It is not trivial surgery, however, and requires good indication and correct implementation. The main causes of cataracts are ageing, eye trauma, eye disease, high refractive error, diseases of the body and certain uses of drugs. Cataracts may also be due to congenital reasons. Its main symptoms include blurred vision, double vision, photophobia (light becomes extremely bothersome), a decrease in depth and colour perception, the incapacity to read small writing, difficulties in driving at night. There are two surgical treatments for this condition: conventional ultrasound phacoemulsification and phacoemulsification using the new femtosecond laser. In both cases, local anaesthetic (drops) is normally used. Eye examinations are recommended as of the age of 45 to detect cataracts as early as possible.