Most people have some sort of refractive error in the eye. In fact, the average Australian is slightly long-sighted However, more serious refractive errors can cause headaches as the small muscles around the eye become tired through overuse.
Six studies provided data from 29 281 persons. In the US, Western European, and Australian year 2000 populations 40 years or older, the estimated crude prevalence for hyperopia of 3 D or greater was 9.9%, 11.6%, and 5.8%, respectively (11.8 million, 21.6 million, and 0.47 million persons). For myopia of -1 D or less, the estimated crude prevalence was 25.4%, 26.6%, and 16.4% (30.4 million, 49.6 million, and 1.3 million persons), respectively, of whom 4.5%, 4.6%, and 2.8% (5.3 million, 8.5 million, and 0.23 million persons), respectively, had myopia of -5 D or less. Projected prevalence rates in 2020 were similar.
Refractive errors affect approximately one third of persons 40 years or older in the United States and Western Europe, and one fifth of Australians in this age group.
The normal eye works like a camera, refracting light through the cornea and lens and focusing an image on the retina. This image should not be noticeably blurry.
The most common refractive errors are:
* Shortsighted Vision (Myopia) - Objects far away look blurry, but anything up close is sharp.
* Long-sighted Vision (Hypermetropia) - Close objects are blurred, but far away is clear.
* Astigmatism - Changes on the curvature of the cornea distort the way light hits the retina and cause blurring;
* Presbyopia - As the eye ages it becomes less flexible and cannot focus as quickly or as sharply, so objects up close become more blurred. It's a normal part of ageing, and usually starts in the 40s.
How are Refractive Errors Treated?
Eyeglasses or contact lenses are the most common methods of correcting refractive errors. They work by refocusing light rays on the retina, compensating for the shape of your eye. Refractive surgery is also an option to correct or improve your vision. These surgical procedures are used to permanently adjust your eye's focus by reshaping the cornea, or front surface of your eye.
There is no scientific evidence that eye exercises, vitamins or pills can prevent or cure refractive errors.
What is LASIK surgery?
LASIK, or Laser In-Situ Keratomileusis, surgery may be used to correct nearsightedness, farsightedness and astigmatism. When a person has any of these eye conditions, his or her eye is too long (nearsightedness), or too short(farsightedness) or the cornea is the wrong curvature resulting in an incorrect focusing power. This results in light rays entering the eye coming into focus without precisely hitting the retina, resulting in blurry vision when looking in the distance.
Some people are still severely visually impaired even after correction, but their visual function can be greatly improved with the use of visual and non-visual aids. Read below about Sightsavers’ low-vision work.
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