Refractive Errors

What are refractive errors? Nearsightedness (also called myopia) is a Refractive errors occur when the shape of the eye condition where objects up close appear clearly, prevents light from focusing directly on the retina. while objects far away appear blurry. With The length of the eyeball (longer or shorter), nearsightedness, light comes to focus in front of changes in the shape of the cornea, or aging of the retina instead of on the retina. the lens can all cause refractive errors. Farsightedness (also called hyperopia) is a common type of refractive error where distant RETINA VITREOUS GEL objects may be seen more clearly than objects IRIS that are near. However, people experience farsightedness differently. Some people may not notice any problems with their vision, especially CORNEA when they are young. For people with significant Image focused on the retina farsightedness, vision can be blurry for objects at PUPIL any distance, near or far. MACULA

LENS Astigmatism is a condition in which the eye does OPTIC NERVE not focus light evenly onto the retina, the light- Normal sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out. The cornea and lens bend (refract) incoming light rays so they focus precisely on the retina at the back of the eye. Presbyopia is an age-related condition in which the ability to focus up close becomes more What is refraction? difficult. As the eye ages, the lens can no longer Refraction is the bending of light as it passes change shape enough to allow the eye to focus through one object to another. Vision occurs close objects clearly. when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then Who is at risk for refractive errors? focused on the retina. The retina converts the light rays into messages that are sent through the Presbyopia affects most adults optic nerve to the brain. The brain interprets these over age 35. Other refractive messages into the images we see. errors can affect both children and adults. Individuals who have parents with certain What are the different types of refractive errors may be more refractive errors? likely to get one or more refractive errors. The most common types of refractive errors are nearsightedness, farsightedness, astigmatism and presbyopia. What are the signs and symptoms of Contact Lenses work by refractive errors? becoming the first refractive Blurred vision is the most common symptom of surface for light rays refractive errors. Other symptoms may include the entering the eye, causing following: a more precise refraction or focus. In many cases, • Double vision contact lenses provide clearer vision, a wider field • Haziness of vision, and greater comfort. They are a safe and • Glare or halos around bright lights effective option if fitted and used properly. It is • Squinting very important to wash your hands and clean your • Headaches lenses as instructed in order to reduce the risk of • Eye strain infection.

How are refractive errors diagnosed? If you have certain eye conditions, you may not An eye care professional can be able to wear contact lenses. Discuss this matter diagnose refractive errors with your eye care professional. during a comprehensive dilated eye examination. Refractive Surgery aims People with a refractive error to change the shape of often visit their eye care the cornea permanently. professional with complaints of visual discomfort This change in eye shape or blurred vision. However, some people don’t restores the focusing power know they aren’t seeing as clearly as they could. of the eye by allowing the light rays to focus precisely on the retina for How are refractive errors corrected? improved vision. There are many types of refractive Refractive errors can be corrected with eyeglasses, surgeries. Your eye care professional can help you contact lenses, or refractive surgery. decide if surgery is an option for you.

Eyeglasses are the simplest For more information about refractive errors and eye and safest way to correct health, visit http://www.nei.nih.gov/healthyeyes. refractive errors. Your eye care professional can prescribe appropriate lenses to correct your refractive error and give you optimal vision.