Saturday, April 4, 2009

Myopia

Myopia is a vision condition in which close objects are seen clearly, but distant ones appear blurred. Myopia occurs when the eyeball is too long or the cornea has too much curvature; thus light is focused in front of, rather than on the retina. As a result, the light entering the eye can not be focused correctly and distant objects look blurred.

Myopia, or nearsightedness, is a very common vision condition affecting about 30 percent of the U.S. population. Some research supports the theory that nearsightedness is hereditary. There is also growing evidence that it is influenced by the visual stress of too much close work.

Usually, Myopia first occurs in school-age children. Because the eye continues to grow during childhood, it typically progresses until about age 20. Oculists and optometrists most commonly correct myopia through the use of corrective lenses, such as glasses or contact lenses. But it can also be corrected by refractive surgery, such as LASIK.

Friday, April 3, 2009

Cataract

A cataract is a clouding that develops in the crystalline lens of the eye. It varies in degree from slight to complete opacity which blocks the passage of light. This gradual yellowing and clouding of the lens may reduce the perception of blue colors. Cataracts usually develops slowly to cause vision loss and are potentially blinding if untreated. Although this condition usually affects both the eyes, one eye is always affected earlier than the other.

The cataract can sometimes cause phacomorphic glaucoma. Very advanced cataracts with weak zonules are liable to dislocation anteriorly or posteriorly. Cataracts develop from a variety of reasons, including advanced age, long-term exposure to ultraviolet light, exposure to radiation, secondary effects of diseases such as diabetes, hypertension, etc.

Cataract operations are usually performed using a local anaesthetic and the patient is allowed to go home the same day. Recent improvements in intraocular technology now allow cataract patients to choose a multifocal lens to create a visual environment in which they are less dependent on glasses. Under some medical systems multifocal lenses cost extra. Traditional intraocular lenses are monofocal.