include './comments/include.php'; ?>
All the causes for defective eye-sight are yet to be found out.
However, some factors are known to be responsible. They have been enlisted below. One or more of these factors might be responsible for a particular eye- defect.
1) Heriditory Causes:
The role of heredity in visual defects is still controversial. Many times, visual defects is still controversial. Many a times, visual defects are found to be present even at birth. such defects include high myopia(pathological variety), high astigmatism, keratoconus, etc. Normally , a child at birth has 2.50 diopters of hypermetropia. Hypermetropia of a greater magnitude should also be considered abnormal.
2) It is true thst if both the parents have good eye-sight, their children rarely suffer from visual defects. If both the parents have similar visual defects e.g. high myopia, a similar defect in their children is found much oftener. That is why such couples are advised against marrying each other.
1) Eye strain
According to the prevalent belief, visual defects lead to eye-strain. However, there are experts who believe that eye-strain is not the result but the cause of visual defects.Incorrect or excessive use of the eyes gives rise to eye-strain. Besides, since the eyes and the mind are intimately connected, mental tension may laso give rise to eye-strain.
2) Excessive close work
This factor has a major share in creating or increasing eye-defects like myopia. It is an indisputable fact that eyes are forced to do excessive and continuous close work. The cases of short-sightedness increase with the increase in education.
The present system of education plays a major role in creating eye troubles. An average child is forced to become a book -worm. Besides studying the texts, a student has to indulge in extra-curicular raeding, home-work etc. Thus, day in and day out, he has to engage his eyes in close work.
It has been observed that children suffer from defective vision. English, after all, is a foreign language. compared to our own languages, it is quite difficult to learn. Consequently, education through english medium means a lot of hard work and concentartion on the part of students. Mental strain arising out of such education leads to eye-strain and finally to eye-defects.
The eyes are not fully developed at birth. Normally, they continue to develop till the child is of six years. Education starts much earlier, usually when a child is of six years. Education starts much earlier, usually when a child is 3 years old. In other words, under-developed and delicate eyes are subjected to unwanted and unaccustomed burden of close work. It would not be an exaggeration to say that we educate our children at the cost of their sight.
It is observed that the body and a visual defect develop simulteously. So the progress of a visual defect in a person usually gets arrested by the time he reaches an age of about twenty years, when the physical growth is almost complete. In the past it was found that children experienced difficulty in seeing at the age of about 13-14 years.
The defect could not increase to a greater extend, as it did not have a great span to grow. But nowadays, unfortunately, we find that a visual defect starts in most children at the age of 5-6 years. Since, the physical development of children is very quick, this visual defect also increases rapidly in a very short time; and when the body is fully developed, we observe that the defect has also developed to a greater extent. It also happens nowadays that the defect continues to increase even after the completion of physical growth. This in an alarming situation.
Dr. francis Young and Dr. Donald Harvis from America have conclusively proved that near-sightedness is directly related to close work. This fact has also been proved under controlled conditions. Before the advent of education, the incidence of short-sightedness was neglegible in Alaska. Under the regime of America, education was made compulsory. In a short span of 10 years, almost 75% of the alskan children had developed short-sightedness. It will be interesting to note that in tribals who still solely rely upon hunting or farming for their livelihood, short sightedness is rare.
Watching television or video should also be termed close work for all practical purposes. This factor is more important for urban youngsters. Indded, this is one reason why parents should be on their alert for their children eye care.
c) Unnecessary use of glasses
It has been mentioned earlier taht eyes continously undergo changes in their shape. during the day, the keeness of sight varies. Under favourable conditions, the sight is sharper and vice versa. when a person uses glasses for a particular eye-defect, he makes thatdefect permanent. according to a survey, the degree of myopia decreases during the vacation owing to lack of close work. At the end
of the vacation, the vision is seen to be much improved. A student who continuously uses glasses during the vacation (because he is advised to do so!)
denies the eyes the chance of self-improvement. If the visual defect is not correctly estimated or if glasses are not made precisely to the prescription, eye-strain might be caused, which would worsen the existing eye-defect or create a new one.
3) Pathological causes
Ceratin eye diseases or defects lso lead to defects of vision. Displacement of the eye -lens may give rise to myopia (short sightedness) , backward displacement causes hypermetropia (long sightedness) and oblique displacement causes astigmatism(irregular sight). The removal of cataractous eye-lens also causes high hypermetropia. A tumour at the rear part of the eyeball may also cause hypermetropia. Conginential glaucoma leads to progressive lengthening of the eyeball and hence myopia. An increase in the refractive index (density) of the eye-lens causers myopia. Defects of the cornea,
gives rise to astigmatism. such defects include corneal injuries or incisions (surgical) and keratoconus( cone -shaped cornea). Most of the above mentioned conditions fall for surgery. defects of cornea can sometimes be controlled by contact lenses.
4) Metabolic causes
Cataract and Glaucoma are the chief causes of visual defects in old age. Both these diseases are , to a graeter or lesser extent, the results of improper metabolism . Excessive use of milk, milk products, tea, coffee, alcohol combined with deficencies of vitamins gives rise to these diseases.
If one considers the above facts, it becomes clear that to avoid visual troubles,
one should (1) prevent eye-strain, (2) curtail close work (3)try to get rid of existing errors of refraction (i.e eye numbers) (4) develop such dietary habits that woubld benefit the eyes (5) try to mantain peak general health
Please submit your Suggestions / Tips here. We value your input
© 2004-2009, Health-Beauty-Guide.com. All rights reserved.