Nearsightedness is known as myopia. This is one of several conditions known as refractive errors, others being astigmatism and farsightedness. In each case, light from images is not focused correctly on the retina and vision is blurry. In most cases, proper glasses or contact lenses correct the problem.
High myopia is a condition in which the amount of nearsightedness is outside the usual range found among most individuals. It usually occurs when the eyeball is larger than normal. Nearby objects may be in focus but distant targets are blurred. It confers increased risk for associated diseases of the retina including retinal detachments.
High myopia by definition is nearsightedness of 6 diopters or more. This amount results in legal blindness unless corrected with the proper lenses. Most individuals with myopia have no additional eye problems and live normal, productive lives. However, others develop degenerative changes in the vitreous (the jelly-like material that fills much of the eye) and in the retina. The retina may develop tears which then progress to a retinal detachment. The macula of the retina (the area with the highest visual resolution) can develop tiny cysts or develop a hole as well. Sometimes hemorrhages occur in the macula which leads to an acute loss of clear vision.
Many factors influence the refractive state of the eye including genetic, developmental, and possibly environmental issues. Isolated, multigenerational families have been reported in which the pattern of high myopia follows a transmission pattern consistent with autosomal dominant inheritance. Multiple gene mutations have been found in such families but in most cases it is not possible to predict the risk of having a specific child with high myopia.
It is well known that children of nearsighted parents are more likely to have myopia.
High myopia is a feature of numerous syndromes as well.
The diagnosis of myopia is made by an eye professional. Whenever the amount of nearsightedness exceeds the normal range (more than about 5 diopters) it is important that a complete ophthalmological examination be done periodically with special attention paid to the retina. Early surgical correction of retinal detachments is important for vision preservation.
There are no proven treatments that halt the progressive enlargement of the eyeball and the only treatment of myopia known to correct vision is with the use of proper corrective lenses.