| Now days we used to spend at least 3 to 6 hours on your computers and 2 to 4 hours watching TV. If facing the computer at least 4 hours a day is part of your daily activities, you need to learn how to take care of your eyes before it is too late. Curing eye problems is possible using modern eye surgery, but nothing beats prevention in saving you from spending and, of course, from losing your vision. Here are some of the vision problems a person can face known as Myopia
Myopia
myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in front of it. This causes the image that one sees when looking at a distant object to be out of focus but in focus when looking at a close object.
Signs and symptoms
Myopia presents with blurry distance vision, but generally gives good near vision. In high myopia, even near vision is affected, and patients cannot read without their glasses for distance.
Diagnosis
A diagnosis of myopia is typically confirmed during an eye examination by an ophthalmologist, optometrist or orthoptist. Frequently an autorefractor or retinoscope is used to give an initial objective assessment of the refractive status of each eye, then a phoropter is used to subjectively refine the
patient's eyeglass prescription.
Prevention
The National Institutes of Health says there is no known way of preventing myopia, and the use of glasses or contact lenses does not affect its progression.
There is no universally accepted method of preventing myopia. Commonly attempted preventive methods include wearing reading glasses, eye drops and participating in more outdoor activities as described below. Some clinicians and researchers recommend plus power (convex) lenses in the form of reading glasses
when engaged in close work or reading instead of using single focal concave lens glasses commonly prescribed. The reasoning behind a convex lens's possible effectiveness in preventing myopia is simple to understand: Convex lenses' refractive property of converging light are used in reading glasses to help
reduce the accommodation needed when reading and doing close work. Although accommodation is irrelevant in Medina's quantitative model of myopia, it reaches the same conclusion. The model teaches a very simple method to prevent myopia.
Near Work causes the lens of the eye to focus (accommodate) excessively, leading to a spasm of the cililary muscles surrounding the lens of the eye. Prolonged ciliary muscle spasms eventually lead to the elongation of the eye resulting in myopia. Some claim[who?] that wearing a plus lens during near work greatly
reduces the eyes need for accommodation and therefore prevents ciliary spasm, and the elongation of the eye. The near work can also be eliminated almost completely by working at the computer from a distance of around 1.5 meters and reading electronic versions of the books (on a computer in a distance).
Chromatic aberration of strong eyeglasses
Prismatic color distortion shown with a camera set for nearsighted focus, and using 9.5 diopter eyeglasses to correct the camera's myopia. (left) Close-up of color shifting through corner of eyeglasses. The light and dark borders visible between color swatches do not exist. (right)
For people with a high degree of myopia, very strong eyeglass prescriptions are needed to correct the focus error. However, strong eyeglass prescriptions have a negative side effect in that off-axis viewing of objects away from the center of the lens results in prismatic movement and separation of colors, known as
chromatic aberration. This prismatic distortion is visible to the wearer as color fringes around strongly contrasting colors. The fringes move around as the wearer's gaze through the lenses changes, and the prismatic shifting reverses on either side, above, and below the exact center of the lenses. Color fringing can
make accurate drawing and painting difficult for users of strong eyeglass prescriptions. |
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