Normal vision for a achromatopsic colour-blind person. Courtesy NIH National Eye InstituteThe same view when achromatopsic and myopic.
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Myopia is a refractive defect of the eye in which light focuses in front of the retina. Those with myopia are often described as nearsighted or short-sighted in that they typically can see nearby objects clearly but distant objects appear blurred because the lens cannot flatten enough. The opposite of myopia is hyperopia or "farsightedness". more...

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Myopia is the most common eyesight problem in the world. About one quarter of the adult population in the United States has myopia. In places like Japan, Singapore and Taiwan, as many as 44% of the adult population is myopic.

Myopia is measured in diopters; specifically, the strength of the corrective lens that must be used to enable the eye to focus distant images correctly on the retina. Myopia of 6.00 diopters or greater is considered high, or severe, myopia. People with high myopia are at greater risk of more acute eye problems such as retinal detachment or glaucoma. They are also more likely to experience floaters.

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 dioptric value (i.e. are concave) which compensates for the excessive positive diopters of the myopic eye.


A recent Australian study found that less than 1 in 10 (8.4%) children between the ages of 4 and 12 were myopic . According to an American study published in Archives of Ophthalmology, nearly 1 in 10 children between the ages of 5 and 17 have myopia , and a recent Brazilian study found that nearly 1 in 8 (13.3%) of the students in one city were myopic .

A recent study involving first-year undergraduate students in the United Kingdom found that 50% of British whites and 53.4% of British Asians were myopic.

The prevalence of myopia in adults in the United States has been estimated to be approximately 25%, however, a study of Jordanian adults aged 17 to 40 found that over half (53.7%) were myopic .

Myopia is more common in Asians and Jews than in Whites, and more common in Whites than in Blacks (Jensen, 1998).



  • Genetic Factors - The most widely held theory of the cause of myopia is that it is mainly hereditary. Measures of the heritability of myopia have yielded figures as high as 89%, and recent research has identified genes that may be responsible: defective versions of the PAX6 gene seem to be associated with myopia in twin studies . Under this theory, the eye is slightly elongated front to back as a result of faults during development, causing images to be focused in front of the retina rather than directly on it. It is usually discovered during the pre-teen years between eight and twelve years of age. It most often worsens gradually as the eye grows during adolescence and then levels off as a person reaches adulthood. Genetic factors can work in various biochemical ways to cause myopia, a weak or degraded connective tissue is a very essential one. Genetic factors include an inherited, increased susceptibility for environmental influences like excessive near work, and the fact that some people do not develop myopia in spite of very adverse conditions is a clear indication that heredity is involved somehow in any case.
  • Environmental Factors - Another theory is that myopia is caused by a weakening of the ciliary muscle which controls the eye's lens. The weak muscle is unable to adjust the lens enough to see far distances, causing far-off things to be blurred. This theory states that the muscle's weakness is usually caused by doing lots of "nearwork", like reading books or using a computer screen. Since the eye rarely has to focus on far distances, the muscle is rarely used and, as a result, becomes weak. Since corrective lenses do the ciliary muscle's work for it, proponents of this theory suggest that they make it even weaker, increasing the problem. Instead, they recommend a variety of eye exercises to strengthen the muscle. A problem with this theory is that mainstream ophthalmology and medicine hold that the ciliary muscle is used when focussing at close distances, and is relaxed when accommodating for distant vision. Other theories suggest that the eyes become strained by the constant extra work involved in "nearwork" and get stuck in the near position, and eye exercises can help loosen the muscles up thereby freeing it for far vision. These primarily mechanical models appear to be in contrast to research results, which show that the myopic elongation of the eye can be caused by the image quality, with biochemical processes as the actuator. Common to both views is, however, that extensive near work and corresponding accommodation can be essential for the onset and the progression of myopia. A variation of this theory was touted by William Bates in the early 1900s. Bates claimed that with nearwork and other "stresses", the extraocular muscles would squeeze the eyeball causing it to elongate.
  • Near work. Near work has been implicated as a contributing factor to myopia in many studies. New research from NSU College of Optometry shows that students exposed to extensive "near work" are at a higher risk of developing myopia, whereas taking summer or winter vacations (which amount to extended breaks from near work) will either reduce or stop myopic progression .
  • Combination of Genetic and Environmental Factors - Regardless of the accuracy of the ciliary muscle theory, a high heritability of myopia (as for any other condition) does not mean that environmental factors and lifestyle have no effect on the development of the condition. High heritability simply means that most of the variation in a particular population at a particular time is due to genetic differences. If the environment changes - as, for example, it has by the introduction of televisions and computers - the incidence of myopia can change as a result, even though heritability remains high. From a little bit different point of view it could be concluded that – determined by heritage – some people are at a higher risk to develop myopia when exposed to modern environmental conditions with a lot of extensive near work like reading. In other words, it is often not the myopia itself, which is inherited, but the reaction to specific environmental conditions - and this reaction can be the onset and the progression of myopia. In China, myopia is more common in those with higher education background ; some studies suggesting that nearwork may exacerbate a genetic predisposition to develop myopia .
  • Diet and nutrition - One 2002 article suggested that myopia may be caused by over-consumption of bread in childhood, or in general by diets too rich in carbohydrates, which can lead to chronic hyperinsulinemia. Various other components of the diet, however, were made responsible for contributing to myopia as well, as summarized in a documentation.


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Myopia and diet - nearsightedness - Nutritional Influences on Illness
From Townsend Letter for Doctors and Patients, 4/1/03 by Melvyn R. Werbach


Several studies have investigated the relationship between body stature as an index of nutritional status and myopia. While the findings are conflicting, by far the largest study reviewed the data of over 100,000 consecutive male military recruits aged 17 to 19 years. It found that persons with severe myopia were slightly shorter and weighed less than those with mild myopia, while the non-myopes were taller and heavier than the myopes. Similarly, the mean body-mass index among the myopes was slightly smaller than among the non-myopes. (1)

In contrast to studies of people who had already become myopic, one small study compared 24 7-year-old children who subsequently developed myopia by the age of 10 to 68 children who were not myopic at the age of 10. The children who were to develop myopia had a generally lower intake of many food components, including total calories, protein and fat as well as several micronutrients. However, there were no significant differences in height and weight between the two groups at age 7 years, (2) suggesting that, unless they required less nutrients than normal children, the deficiencies were too subtle to affect growth.

Animal Protein

Compared with normally sighted children, myopic children were found to refuse animal protein (from fish, milk, cheese and eggs) more often - although they did eat meat. Moreover, myopia in children who refused to eat animal protein from those sources was found to be both more common and more severe. While 5% of normal children refused two protein sources, 7% of stationary myopes and 11% of active myopes did so. The most striking difference between the two groups was in milk consumption, with over three times as many advancing myopes refusing milk as compared to stationary myopes (16% vs. 5%). (3)

In a controlled clinical trial, 91 myopic school children were placed on a diet in which 10% of caloric intake was animal protein without any change in total calories. Calcium caseinate was used as a supplement for the 72 children who refused animal protein as ordinary food due to taste or lack of appetite.

After one to two years, compared to untreated controls, treated children showed a substantially lower average annual increase in myopia. In the younger children, the deterioration was greater in the controls by an average of 0.5 diopter each year while, in the older children, the progress of myopia was all but arrested in the treated group. The more severe the myopia at the start of treatment, the bigger the difference between treated and untreated groups. In general, the treated group deteriorated at about one-third the rate of the untreated group.

After six months, for the 16 children who consumed the amount of calcium caseinate advised, the mean change in refraction was an improvement of 0.02 diopters; in the 42 who took "some" calcium caseinate, the mean change was a deterioration of 0.16 diopters; and in the 14 who refused any calcium caseinate, there was a deterioration of 0.22 diopters. (4)

Dietary Fiber

There is preliminary data suggesting a relationship between the intake of dietary fiber and myopia. In a retrospective study of 120 binocular non-strabismic optometric patients aged 7 to 38 years, dietary fiber intake was significantly related to refractive strata, with myopes consuming an average of only 39% as much fiber in grams as hyperopes (farsighted people) (5.3 g vs. 13.55g).

The author suggests that this finding may be because hyperopes with higher fiber intake were eating more unrefined foods with better trace mineral availability, that the higher fiber intakes may result in more thorough mixing with saliva resulting in improved nutrient absorption, or because dietary fiber is often correlated with dietary folate, and the intake of dietary folate is highly correlated with myopia prevention/reversal. (5)

Refined Carbohydrates

Consistent with the hypothesis that a high intake of dietary fiber may be protective, there is evidence that a high intake of refined carbohydrates may promote myopia. When rats received a high sucrose diet upon weaning, the normal hypermetropia was significantly reduced (that is, a relative myopia developed) compared to controls. Then, when the sucrose and control group were reversed, myopia developed in the rats that were now receiving the high-sucrose diet. This myopia failed to reverse, however, when they were switched to a sucrose-free diet. (6)

There is also preliminary data in humans suggesting that the consumption of refined carbohydrates may be associated with the development of myopia. When the diets of optometric patients between the ages of 7 and 38 years were studied, myopes were found to have a significantly higher ratio of consumption of refined carbohydrates to total carbohydrates than hyperopes. Moreover, hyperopes had a lower ratio of consumption of refined to total carbohydrates than emmetropes (people who are neither nearsighted nor farsighted). (5)

In summary, inadequate childhood nutrition - especially in regard to animal protein and dietary fiber - appears to be a risk factor for the development of myopia.


(1.) Rosner M et al. Myopia and stature: findings in a population of 106,926 males. Eur J Ophthalmal 5(1):1-6, 1995

(2.) Edwards MH. Do variations in normal nutrition play a role in the development of myopia? Optom Vis Sci 73(10):638-43, 1996

(3.) Gardiner PA. Observations an the food habits of myopic children. Br Med J ii:699-700, 1956

(4.) Gardiner PA. Dietary treatment of myopia in children. Lancet i:1152-5, 1958

(5.) Lane BC. Myopia prevention and reversal: new data confirms the interaction of accommodative stress and deficit-inducing nutrition. J Int Acad Prev Med November, 1982:17-30

(6.) Bardiger M, Stock AL. The effects of sucrose-containing diets low in protein on ocular refraction in the rat. Proc Nutr Soc 31(1):4A-5A, 1972

Modified from Werbach MR with Moss J. Textbook of Nutritional Medicine. Tarzana, California, Third Line Press, Inc., 1999.

In his latest book, Dr. Werbach has assembled a unique library of case reports concerning nutritional and herbal treatments for 155 different illnesses. It is available in print or on diskette from Third Line Press Inc., 4751 Viviana Drive, Tarzana. California 91356, USA. (Phone: 818-996-0076; Fax: 818-774-1575; internet:; e-mail:

COPYRIGHT 2003 The Townsend Letter Group
COPYRIGHT 2003 Gale Group

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