Nearsightedness, or myopia, is the most common refractive error of the eye, and it has become more prevalent in recent years. Let's explore what that means
In fact, a recent study by the National Eye Institute (NEI) shows the prevalence of myopia grew from 25 percent of the U.S. population (ages 12 to 54) in 1971-1972 to a staggering 41.6 percent in 1999-2004.
Though the exact cause for this increase in nearsightedness is unknown, doctors feel it has something to do with eye fatigue from computer use and other extended near vision tasks, coupled with a genetic predisposition for myopia.
Myopia Symptoms And Signs
If you are nearsighted, you'll have difficulty reading signs and seeing distant objects clearly, but will be able to see clearly for close-up tasks like reading and computer use.
Other signs include squinting, eye strain and headaches. Feeling fatigued when driving or playing sports also can be a symptom of uncorrected nearsightedness.
If you experience these signs or symptoms while wearing your glasses or contact lenses, schedule a comprehensive eye examination with your optometrist or ophthalmologist to see if you need a stronger prescription.
What Causes Myopia?
Myopia occurs when the eye is too long relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface which is wjhat causes pbjects that are far away to appear blurry. Nearsightedness also can be caused by the cornea and/or lens being too curved for the length of the eye.
Myopia usually begins in childhood and you may have a higher risk if your parents are nearsighted. In many cases, nearsightedness stabilizes in early adulthood but can continue to progress with age.
Nearsightedness is corrected with glasses, contact lenses or refractive surgery. Depending on the value of your myopia, you may need to wear your glasses or contact lenses all the time or, if your prescroption is weaker, only when you need very clear distance vision, like when driving, seeing a chalkboard or watching a movie.
Good choices for eyeglass lenses for nearsightedness include high-index lenses (for thinner, lighter glasses) and anti-reflective coating. Also, consider photochromic lenses to protect your eyes from UV and high-energy blue light and to reduce your need for a separate pair of prescription sunglasses outdoors.
If you're nearsighted, the first number ("sphere") on your eyeglasses prescription or contact lens prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted you are.
With more and more people getting nearsighted these days, there is a lot of interest in finding ways to control the progression of myopia in childhood.
A number of different techniques have been tried — including fitting children with bifocals, progressive lenses and gas permeable contact lenses — with mixed results.
In most cases, nearsightedness is simply a minor inconvenience and poses little or no risk to the health of the eye. But sometimes myopia can be so progressive and severe it is considered a degenerative condition.
Degenerative myopia (also called malignant or pathological myopia) is a relatively rare condition that is believed to be hereditary and usually begins in early childhood. About 2 percent of Americans are afflicted, and degenerative myopia is a leading cause of legal blindness.
In malignant myopia, the elongation of the eyeball can occur rapidly, leading to a quick and severe progression of myopia and loss of vision. People with the condition have a significantly increased risk of retinal detachment and other degenerative changes in the back of the eye, including bleeding in the eye from abnormal blood vessel growth (neovascularization).
Degenerative myopia also may increase the risk of cataracts.
Surgical treatment for complications of degenerative myopia includes a combination drug and laser procedure called photodynamic therapy that also is used for the treatment of macular degeneration.