Parents are usually upset when their children are prescribed glasses. It is vital to understand that prescription lenses are required for correction of refractive error. An average person's eye is able to focus rays of light on the sensory layer of the eye called retina which transfers data to brain for further visual processing. In a person having refractive error, the rays of light do not get focused at the desired point. When the focus is in front of retina it is called "Myopia" and when it is at the back of the retina it is called "Hypermetropia". Corrective lenses are required to shift the focus in front or back and the patients are prescribed spherical lenses that are convex (plus power) or concave (minus power). When the rays of light get focused in different planes the patient needs to have cylindrical lenses of either power.
The refractive error is neither a disease nor a deficiency of minerals or vitamins. It is important to use corrective lenses for proper development of visual function. In certain situations when the two eyes have different refractive power errors the better eye can suppress the other eye which becomes "lazy" for ever. Correction before the age of 6 years and other supportive measures can prevent lazy eye (Amblyopia).
There are many genes involved in inheritance of refractive errors. The probability of transmitting to the next generation is more in parents having refractive error.
Parents say that the eyes are "weak", which is not an appropriate expression as eyes function normally with correction. Eating balanced diet and vitamin A supplementation helps in visual function but will not change the power per se. The power can change till 18 years of age and an annual check up is important. Use of contact lenses does not stabilise the power in children. Reading in poor light, reading from a distance shorter than 25-30 cms leads to increase in Myopia.
Consult specialist if vision does not improve with corrective lenses to rule out other conditions.