Nearsightedness Vs. Farsightedness

The saying 20 - 20 vision does not actually imply perfect vision; it implies normal vision. People whose eyes actually focus light exactly on the retina can achieve better than the 20 - 20 results in an eye test. Nearsightedness and farsightedness are the two most common eye problems.

Although genetic predisposition is responsible for it to some extent, lack of proper eye care also largely contributes to such eye problems.

Incorrect posture while reading, inappropriate projection of light on the book, reading in dimly-lit room, watching TV for long hours, playing video games, and unhealthy eating practices are equally responsible for these two conditions. Following are a few differences between the two vision problems.

Although you might have heard these two terms quite often, there may be some people who may get confused with the two. Nearsightedness/Myopia/Short-sightedness is a condition in which the person is able to see objects that are closely located, but finds it difficult to see those at a distance.

Farsightedness/Hyperopia/Long-sightedness is the exact opposite of this condition. A long-sighted person can see distant objects, but finds it difficult to see those at a hand's distance. Both these conditions originate from the irregularities in the shape of the cornea (clear front window of the eye).

For a person to see clearly, the light rays should fall on the retina in such a way that the image is formed exactly on the retina, and not in front of it or behind it. In case of people with myopia, the cornea is elongated or is longer than in an average eye.

As a result, the light rays do not fall properly on the eye, and the image is formed in front of the retina, rather than on it. The excess curvature of the cornea might be the result of inheritance or due to the lack of proper eye care.

This condition is very common in young people with almost 30% of Americans affected by it. Inherited myopia is normally detected when the child starts going to grade school.

Difficulty in copying things from blackboard, headaches, etc., usually triggers the need to see an eye specialist. Often, the condition progresses as the child grows up. Severe myopia may lead to retinal detachment, which could result in vision loss. However, there are number of ways in which this condition can be corrected.

Hyperopia, on the other hand is caused due to very short cornea. The eyeball of these people is smaller than that of average people. As a result, the image falls behind the retina and not upon it. Long-sightedness is more prevalent in people over 40 years of age.

These people have crisp vision to view faraway objects, but have trouble seeing things that are too near. However, severe hyperopia may hamper distant vision as well. Hyperopia in children though rare, is not unheard of and is often a product of genetic predisposition.

The test for myopia or hyperopia is either done as a part of routine eye examination or for diagnostic purposes. An instrument called phoropter is used to measure the refractive error. The curvature of the cornea is studied and based on that proper vision correction mechanism is suggested.

Both of these problems can be easily resolved by the use of respective glasses, contact lenses, or surgeries. Reading glasses adjust the light rays in such a way that the image exactly falls on the retina. Contact lenses do the same job while sitting on the eyeball itself.

Surgery can be considered as an option, either for cosmetic reasons or to cure severe refractive error. The possibility of developing these problems, especially nearsightedness, could be lowered with proper eye care.

Disclaimer: This story is for informative purposes only, and should not be used as a replacement for expert medical advice.