EYE CARE : Eye Disorders and Vision Problems Including Cataracts, Lasik Eye Surgery, Blindness, Glaucoma and Eye Allergy.

EYECARE : VISION : MYOPIA
Myopia also called near- or short-sightedness, is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed. Those with myopia see nearby objects clearly but distant objects appear blurred. With myopia, the eyeball is too long, or the cornea is too steep, so images are focused in the vitreous inside the eye rather than on the retina at the back of the eye. The opposite defect of myopia is hyperopia or "farsightedness" or "long-sightedness" - this is where the cornea is too flat or the eye is too short.

Mainstream ophthalmologists and optometrists most commonly correct myopia through the use of corrective lenses, such as glasses or contact lenses. It may also be corrected by refractive surgery, such as LASIK. The corrective lenses have a negative optical power (i.e. are concave) which compensates for the excessive positive diopters of the myopic eye. In some cases, pinhole glasses are used by patients with low-level myopia. These work by reducing the blur circle formed on the retina.The prevalence of myopia in has been reported as high as 70-90% in some Asian countries. 30-40% in Europe and the United States, and 10-20% in Africa.

Ethnicity
Myopia is less common in black, Nubians, and Sudanese people. In Americans between the ages of 12 and 54, myopia has been found to affect whites less than blacks. Asians had the highest prevalence (78.5%), followed by Hispanics (13.2%). Whites had the lowest prevalence of myopia (4.4%), which was not significantly different from African Americans (6.6%). For hyperopia, whites had the highest prevalence (19.3%), followed by Hispanics (12.7%). Asians had the lowest prevalence of hyperopia (6.3%) and were not significantly different from African Americans (6.4%). For astigmatism, Asians and Hispanics had the highest prevalences (33.6% and 36.9%, respectively) and did not differ from each other. African Americans had the lowest prevalence of astigmatism (20.0%), followed by whites (26.4%).

Education, Intelligence, and IQ
A number of studies have shown that the prevalence of myopia increases with level of education and many studies have shown a relationship between myopia and IQ. However, care must be taken in interpreting these results as correlation does not imply causation.According to Arthur Jensen, myopes average 7-8 IQ points higher than non-myopes. The relationship also holds within families, and siblings with a higher degree of refraction error average higher IQs than siblings with less refraction error. Jensen believes that this indicates myopia and IQ are pleiotropically related as they are caused or influenced by the same genes. The mechanism that has caused a relationship between myopia and IQ is not yet known with certainty.(1)