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Vision
 
 

The eye focuses by bending incoming light rays to meet at a single point. Ideally this single point lands directly on the fovea, the central point of the retina. If the light rays reach this perfect placement, you experience clear, sharp images.

However, if the focal point is behind the retina or in front of the retina, the image on the retina will not be fully formed and will be interpreted by your brain as blurred. This is very much like focusing a projector onto a blank movie screen. If the projection is too close or too far from the screen, the images are blurred. Set at the correct distance, you may enjoy the show!

When you have an eye examination at Desert Vision Center, Dr. Tokuhara will determine whether you are nearsighted, farsighted, astigmatic, and/or presbyopic by measuring where your eye focuses light. Depending on your refraction, he will discuss different treatment options with you.


Nearsightedness (myopia):

Nearsighted individuals typically have problems seeing well at a distance and are forced to wear glasses or contact lenses. The nearsighted eye is usually longer than a normal eye, and its cornea may also be steeper. Therefore, when light passes through the cornea and lens, it is focused in front of the retina. This will make distant images appear blurred.


Farsightedness (hyperopia):

Farsighted individuals typically develop problems reading up close before the age of 40. The farsighted eye is usually slightly shorter than a normal eye and may have a flatter cornea. Thus, the light of distant objects focuses behind the retina unless the natural lens can compensate fully. Near objects require even greater focusing power to be seen clearly and therefore, blur more easily.


Astigmatism:

Asymmetric steepening of the cornea or natural lens causes light to be focused unevenly, which is the main optical problem in astigmatism. To individuals with uncorrected astigmatism, images may look blurry or shadowed. Astigmatism can accompany any form of refractive error and is very common. Astigmatism can be corrected with glasses, contact lenses, corneal relaxing incisions,  and special implant lenses.


Presbyopia:

Presbyopia is a condition that typically becomes noticeable for most people around age 45. In children and young adults, the lens inside the eye can easily focus on distant and near objects. With age, the lens loses its ability to focus adequately.

Although presbyopia is not completely understood, it is thought that the lens and its supporting structures lose the ability to make the lens longer during close vision effort. To compensate, affected individuals usually find that holding reading material further away makes the image clearer. Ultimately, aids such as reading glasses are typically needed by the mid-forties. Besides glasses, presbyopia can be dealt with in a number of ways. Options include: monovision and multifocal contact lenses, and new presbyopia correcting implant lenses.