Myopia, or nearsightedness, is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed.
Those with myopia typically can see nearby objects clearly but distant objects appear blurred.
The opposite defect of myopia is hyperopia or "far-sightedness" or "long-sightedness". This is where the cornea is too flat or the eye is too short.
Mainstream ophthalmologists and optometrists most commonly correct myopia through the use of corrective lenses, such as glasses or contact lenses. It may also be corrected by refractive surgery, such as LASIK.
The corrective lenses have a negative dioptric value (i.e. are concave) which compensates for the excessive positive diopters of the myopic eye.
Eyeglasses, contact lenses, and refractive surgery are the primary options to treat the visual symptoms of those with myopia. Orthokeratology is the practice of using special rigid contact lenses to flatten the cornea to reduce myopia.
Practitioners and advocates of alternative therapies often recommend eye exercises and relaxation techniques such as the Bates method, however, the efficacy of these practices are disputed by mainstream eye care practitioners.
There is no universally accepted method of preventing myopia. Some clinicians and researchers recommend plus power lenses in the form of single vision reading lenses or bifocals although recent Malaysian study suggested that undercorrection of myopia caused more rapid progression of myopia, the reliability of the data have been called into question.