When light rays are bent or refracted as they pass through the cornea and lens, vision occurs. Under normal circumstances the light rays focus directly on the retina and are converted into messages sent to the brain via the optic nerve. These messages are then interpreted into what we see.
Myopia or nearsightedness occurs when the light enters the eye incorrectly or the ray is not properly focused on the retina. In such cases, distant objects look blurred though nearby objects can be seen clearly.
As we age, the eyes lose their natural ability to focus properly. This loss of focus makes nearby objects look blurred and results in a condition known as presbyopia. It is possible to suffer from presybopia along with another refractive eye condition such as myopia, astigmatism or hyperopia (farsightedness). If you find it difficult to read small print or see things that are close to you or if you suffer from recurring headaches or complain of eyestrain you may be suffering from presbyopia.
Causes: Myopia occurs when the physical length of the eye is larger than the optical length. When this happens, it becomes difficult for the light rays to focus directly on the retina and thus causes distant objects to look blurred. While myopia affects both men and women equally, it does tend to be more common if there is a family history of the condition. Myopia may worsen during the growth years of childhood and adolescence and may require frequent changes of eyeglasses or contact lenses. Contrary to popular opinion, watching too much TV or reading too much does not cause myopia. However, spending too much time on the computer or reading too much may aggravate the condition if you already have it. In some cases nearsightedness may be a result of premature birth, other eye diseases, uncontrolled diabetes, or cataracts. Myopia is not a harmful condition and in most cases except for nearsightedness the eyes are healthy. In very rare cases severe myopia may lead to retinal degeneration and blindness.
Presbyopia occurs when the soft lens of the eye starts to harden with age. As the lens hardens and loses flexibility, the ability of the eye to focus properly diminishes and leads to blurred vision (especially of nearby objects). Aging also affects the muscle fibers around the lens thus making it difficult for the eye to focus on objects that are nearby. Presbyopia is a condition that starts to develop between the ages of 40 and 50 and affects pretty much everyone though for some people the loss of vision is more pronounced than in others.
Treatment: A general ophthalmic exam will help diagnose myopia. You doctor may also conduct additional tests such as an eye pressure measurement test, a refraction test, and a retinal examination to determine the correct prescription for eyeglasses or contact lenses. Wearing proper eyeglasses or contact lenses helps treat myopia by shifting the focus of the light rays directly on to the retina. This helps reduce blurring and produces a sharper image of distant objects. LASIK or corrective laser eye surgery is another popular option for individual who do not want to wear glasses or lenses. The earlier myopia is diagnosed and treated the better it is for the person concerned. School going children especially may suffer as a result of nearsightedness. If you notice your child sitting close to the television or holding a book close to his eyes when reading, he may be suffering from myopia. It is best to consult with a doctor or eye specialist at the earliest in such cases. Remember there is no way to prevent nearsightedness only to treat it as soon as possible.
Presbyopia can be corrected with bi-focal or progressive addition lenses for eyeglasses or contact lenses. Multi-focal lens implants may also be inserted at the time of cataract surgery and can help correct vision in such cases.