Basically when decreased vision interferes with the patient's daily activities. The specialist may also consider surgery if he or she appreciates an increase in intraocular pressure or other complications related to the progression of the cataract, in these cases, even if the patient has a certain degree of vision that allows them to carry out their usual activities, it is advisable to consider the extraction of the cataract to avoid irreversible damage. It is cnot to wait until the patient has almost completely lost vision to consider surgery, as this practice can carry risks, a more complex intervention because it is a harder cataract or with poor visibility for the surgeon. In general, we recommend going to the ophthalmologist in the initial stages of cataracts, so that he is the one who controls the evolution and advises us when to perform the surgery. On some occasions, we recommend lens surgery to especially correct refractive errors, it is what is called surgery "phagorefractive”: Is indicated in patients with high presbyopia, myopia or farsightedness, the lens surgery with a multifocal intraocular lens implant not only improves vision, but at the same time allows you to dispense with glasses or contact lenses.