Currently, PRK is being used to treat between 1.0 and 12.0 diopters of myopia (with up to 4.0 diopters of astigmatism) and 1.0 to 6.0 diopters of hyperopia (with up to 4.0 diopters of astigmatism). The PRK procedure itself usually takes only 1 to 2 minutes to perform.