Lasik Surgery: What Happens Before and During Surgery
Pre-Surgery RequirementsPatients wearing soft contact lenses typically are instructed to stop wearing them approximately 7 to 10 days before surgery. Some surgeons recommend that patients wearing hard contact lenses should stop wearing them for a minimum of six weeks plus another six weeks for every three years the hard contacts had been worn.Before the surgery, the surfaces of the patient’s corneas are examined with a computer-controlled scanning device to determine their exact shape. Using low-power lasers, it creates a topographic map of the cornea. This process also detects astigmatism and other irregularities in the shape of the cornea.Using this information, the surgeon calculates the amount and locations of corneal tissue to be removed during the operation. The patient typically is prescribed an antibiotic to start taking beforehand, to minimize the risk of infection after the procedure.Higher order Aberrations are visual problems not captured in a traditional eye exam. In a young healthy eye, the level of higher order aberrations are typically low and insignificant.Concern has long plagued the tendency of refractive surgeries to induce higher order aberration not correctible by traditional contacts or glasses. The advancement of lasik technique and technologies has helped eliminate the risk of clinically significant visual impairment after the surgery.There has been controversy about the amount of higher order aberrations that would lead to significant vision impairment. In extreme cases, where proper policy was not followed and before key advances, some people could suffer rather debilitating symptoms including serious loss of contrast sensitivity in poor lighting situations.Over time, most of the attention has been focused on spherical aberration. Lasik and PRK tend to induce spherical aberration, because of the tendency of the laser to undercorrect as it moves outward from the center of the treatment zone. 