Myopia, or nearsightedness, is the most common cause of impaired vision. While objects viewed at close distances are clear, myopia causes objects to appear blurry at a distance.
Myopia correction requires lenses with NEGATIVE dioptric value.
Myopia causes distance vision to be out of focus. It can be caused by an eye shape that is too long or by an excessive curvature of the cornea, which causes light rays to focus in front of the retina rather than directly on it. Myopia can be inherited or exacerbated by eye strain and fatigue, and if undiagnosed often causes squinting and headaches. Prolonged use of computers and other digital devices can worsen these symptoms. The severity of nearsightedness is expressed in diopters. For example, –2.50 is considered low myopia, and –6.00 and higher indicates high myopia.
Glasses and contact lenses help to change the point where the light rays are focused on the retina, and are the most convenient and cost-effective methods of correcting myopia. Many people prefer the convenience of contact lenses and the fact that they afford perfect peripheral vision, which is not possible with glasses. In some cases, myopia can be corrected permanently with laser surgery.
In the picture above, you can see an illustration of how myopia affects your vision. Light rays entering the eye are focused before the retina, causing images to appear blurry. You can see how someone with myopia sees the world compared with someone with normal vision.