Refractive errors of the eye are relatively common and are seen in around 20 percent of children examined. An inability to focus clearly on objects, a refractive error may occur for more than one reason. The strain on the eyes from a refractive error is k
nown to cause headaches. This has been the cause of some small controversy as many doctors now think that refractive error is often overdiagnosed as the cause of headaches.
Astigmatism may occur either in childhood or adulthood. It is caused by an abnormal curvature of the cornea which causes the focal point of one eye to be mismatched with the other. Objects both up close and at a distance may appear blurry. Headaches from the strain on the eyes from this condition are quite common. Usually this refractive error and its headaches can be corrected with glasses or contact lenses that correct the imbalance.
Hyperopia is most commonly called farsightedness. This refractive error of the eye is usually caused by the axis of the eyeball being too short. The headaches associated with this refractive error are also the result of too much strain being placed on the eyes from an attempt to correct for the imbalance. Eyeglasses and contact lenses are a relatively easy way to correct for the condition and to eliminate the headaches that are associated with this refractive error.
In relation to your eyes, refraction refers to how light waves bend as they pass through your cornea and lens. Your eye’s ability to refract light determines its ability to focus light, which establishes how well you see.
Your eye has a refractive error if it cannot focus an image sharply. Determining the lens prescription needed to correct the error is called a refraction or refraction assessment.
Your eye’s ability to refract light depends on the overall length of the eye and the curvature of the eye’s surface (cornea). If the eye is too long, images mistakenly focused in front of the retina are out of focus when they reach the retina, and you are nearsighted. If the eye is too short, images are not in focus by the time they get to the retina, and you are farsighted. If the cornea is not properly curved, you have astigmatism.
According to the American Academy of Ophthalmology, refractive errors of the eye are the most common eye condition; however, they are not diseases. To have clear vision, the light that enters the eye has to be bent (refracted) through the cornea (the clear portion at the front of the eye) and the lens and come into focus on the retina (the layer of cells at the rear of the eye) for clear vision to occur. However, when the shape of the eye is not normal, refractive errors happen and vision becomes blurry. There are four main types of refractive eye problems: nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia.
Nearsightedness occurs when the eyeball itself is too long or the cornea is too pointed. This causes the light that enters the eye to come into focus in front of the retina instead of on the retina. People who are nearsighted can see objects that are close to the eye very clearly but items in the distance are blurry. This condition can get worse during the teenage years because this is a period of rapid growth. People who are very nearsighted may be at higher risk for developing a detached retina.
In a person with farsightedness, the eyeball is smaller than normal. Light focuses behind the retina in hyperopic eyes; objects that are close to the eye like the words in a book are blurry and difficult to see. This condition can be seen in children; parents may notice the child squinting or rubbing the eyes. Hyperopia is often an inherited condition; however, the condition may improve in children as they get older.
