Refractive Errors
There are many things that can make someone’s vision blurry, but the most common cause of blurry vision is refractive errors. These are most often correctable with glasses, contacts, or refractive surgery like LASIK.
For the eye to be able to see clearly, the light rays that enter the eye must be bent so that they focus properly on the retina, the back of the eye. The light rays activate the retina to send signals to the brain through the optic nerve. The cornea and lens are the two structures in the eye that focus light rays. A refractive error simply means that the shape of the eye, cornea or lens doesn’t focus the light properly, so that the image you see is blurred.
Myopia (nearsightedness) means that the rays of light are focused in front of the retina. This makes near objects to appear clear, and far objects blurred. Myopia is inherited, and often found in young children. During the teenage years, when the body grows rapidly, myopia will usually get worse. Most types of myopia are simply corrected with glasses, contacts, or refractive surgery, but there are types of myopia that are associated with retinal detachments or bleeding in the back of the eye, so it is important to have your eyes checked by an ophthalmologist.
Hyperopia (farsightedness) means that the light rays are focused “behind the eye.” Another way of picturing this is if the eye were longer, then the light would be focused on the retina. Farsightedness is also usually inherited, and is usually found in most children. As the eye grows along with the body, the degree of farsightedness often decreases. Hyperopia in older individuals, however, means that objects both far away and close up are blurry.
Astigmatism (distorted vision) is a term used to describe a cornea that curves more in one direction than in the other, like a football. Astigmatism blurs objects for both far and near, and it can also occur in combination with myopia or hyperopia.
Presbyopia (Aging eyes) is when the aging lens becomes more rigid, and cannot change shape as easily as it once did. This prevents the eye from focusing at close range. Presbyopia is a natural aging process, and occurs in everybody. It can occur along with myopia, hyperopia, or astigmatism.
Myopia, hyperopia, and astigmatism are often inherited. There is no way to predict accurately what the refractive error will be in the future, and there is no proven way to prevent any refractive error from occurring or getting worse.
Correcting a refractive error is most commonly accomplished through the use of glasses or contacts. Recently, refractive surgery has become a popular alternative, but these surgical methods are usually permanent changes and are associated with certain risks and complications. Your ophthalmologist will be able to help you determine your refractive error, and also which method of correction is best suited to you.
