Health Library
The Health Library is a collection of health and wellness resources created for learning and accessibility. Select a topic below for related health information or search for a topic in the search bar for more information on other medical conditions.
Refractive Errors
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Prescriptions for glasses have two main components: shape and power. The shape of a lens determines the type of correction. Concave, or minus, spherical lenses are thicker at the sides than in the middle to correct nearsightedness (myopia). Convex, or plus, lenses are thicker in the middle than at the...
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Prescriptions for glasses have two main components: shape and power. The shape of a lens determines the type of correction. Concave, or minus, spherical lenses are thicker at the sides than in the middle to correct nearsightedness (myopia). Convex, or plus, lenses are thicker in the middle than at the...
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What is farsightedness? People who are farsighted see things at a distance more easily than they see things up close. If you are very farsighted, close objects may be so blurry that you can't do tasks such as reading or sewing. A farsighted eye sees things differently than an eye that is not farsighted. Farsightedness...
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Photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK) for farsightedness use a laser to reshape the cornea so that light is refocused on the retina. The laser reshapes the cornea accurately without damaging nearby tissues. No surgical cut is needed. Either procedure may be used to correct...
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Laser in-situ keratomileusis (LASIK) is the preferred procedure for correcting farsightedness (hyperopia). It changes the shape of the eye. In LASIK, a thin flap is made on the cornea using a blade or laser. The flap is lifted, and a laser is applied to the central corneal tissue. The laser makes contact with the cornea...