Myopia or nearsightedness is a condition where a person has trouble seeing things that are far away. The eye finds it difficult to focus the light directly on the retina since the physical length of the eye is greater than the optical length. Such a person suffering myopia finds distant objects blurred and might need to squint to see them clearer. Symptoms of myopia are eyestrain and sometimes headache. This is quickly noticed in school going children who have difficultly reading the blackboard. In fact myopia worsens during the growth years and then stabilizes after the teens. Regular eye tests with refraction test help in diagnosing the degree of refraction lens needed. Spectacles or contact lens are prescribed to correct the focus of the light image on the retina thereby producing a clear image. LASIK is also performed to correct myopia. Orthokeratology involves usage of special rigid contact lenses to flatten the cornea to reduce myopia.
Presbyopia is a vision problem where there is difficulty in seeing close objects. With age, the capacity of the lens to change its length or shape to focus on nearer objects becomes difficult. This loss of elasticity usually happens with persons in their 40s. You can identify presbyopia when a person finds it difficult to focus on near objects and suffers headache and eye strain. Visual acuity, refraction test and retinal examination aid in diagnosing the extent of correction needed. Reading glasses can be worn to rectify this vision problem. Those who also suffer nearsightedness can go in for bifocal lens to also correct both vision problems.
Human vision is an example of binocular vision where the images from both eyes are blended or fused to form a single image giving a wide range of view. This also allows for depth perception. The process whereby the separate images from the eyes are successfully fused into one in the brain is called stereopsis or stereoscopic vision. Problems in binocular vision might happen due to astigmatism, nearsightedness, myopia, farsightedness, cerebral palsy and cataract.
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Diseases, Symptoms, Tests and Treatment arranged in alphabetical order:
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Collection of Pages - Last revised Date: September 23, 2019