The World Health Organization says that about 153 million people on the planet suffer from so-called refractive errors. These are eye problems caused by imperfections in the cornea, often resulting in nearsightedness (myopia) or farsightedness (hyperopia). One way correct these refractive errors is to manipulate or reshape the cornea using a treatment known as Laser Assisted in Situ Keratomileusis or LASIK.

Blurry vision is just one symptom of refractive errors: people experiencing double vision, haziness, or even pain when looking directly at a light source may be suffering from refractive errors without even knowing it. A proper diagnosis of these symptoms is needed because they can be treated simply by wearing special glasses or contact lenses. On the other hand, LASIK can be the only way to treat these symptoms permanently.

LASIK is also used to help treat astigmatism, the inability of the eye to focus on an object because of a problem in the cornea. Specifically, the cornea of an astigmatic person is shaped irregularly and a laser is needed to “smoothen” its edges. In theory, LASIK can also be used to treat presbyopia: the gradual deterioration of vision due to old age. However, presbyopia may also affect other parts of the eye, which is beyond the reach of a LASIK treatment.