The vast majority of vision problems are a result of imperfect formation of the eye’s refractive system—or in other words, when the shape of the eye prevents light from focusing directly on the retina. The length of the eyeball or an aging of the lens can cause refractive errors. In order to see clearly, there are a number of eye structures that must develop properly so that we don’t develop a need for vision correction. Most people have one or more of these conditions in varying degrees.
We are able to “see” when light rays are refracted as they pass through the cornea and the lens. The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. There are many ways that even the slightest imperfection in the development of an eye can result in a condition known as ametropia, which simply means that the eye’s refractive system isn’t focusing light at the proper point. The most common types of refractive errors are near-sightedness, far-sightedness, astigmatism and presbyopia.
Myopia (near-sightedness) is the most common vision problem. The condition causes people where objects up close appear clearly, while objects far away appear either not as clearly or blurry. The cause of this condition is that either the eyeball is too long or the lens/cornea optical system of the eye is too strong.
Hyperopia (Far-sightedness) is the second most common type of refractive error. Far-sightedness is when distant objects are seen more clearly than objects that are near, but interestingly enough, people experience this condition differently. Some people may not notice any problems with their vision, when they are young, while others will experience significant blurriness for objects at any distance, near or far. In contrast to Myopia, the cause of this condition is that either the eyeball is too short or the lens/cornea optical system of the eye is too weak.
Other common vision problems include Astigmatism and Presbyopia. Astigmatism is a condition where the person has an irregularly shaped cornea (more like a football), which causes images to be blurry and stretched out. Presbyopia, in contrast, is simply a result of the normal aging process where there is a gradual loss of flexibility of the crystalline lens and its ability to produce clear images.
An eye care professional can diagnose refractive errors or other vision problem during a comprehensive dilated eye examination. Refractive errors can be corrected with eyeglasses, contact lenses, or laser surgery.