Highly myopic eyes are also liable to loss vision from cataract and glaucoma. Stresses in the retina and the adjacent parts of the vitreous gel are also partly responsible for a predisposition to peripheral retinal tears, which may go on to admit vitreous fluid into the sub-retinal space, producing retinal detachment. This process of macular scarring is telined myopic macular degeneration. In the central retina, damage to the functioning of the macula results in vision loss. The sclera, the choroid, the retina and the interface between the retina and the vitreous gel are all affected by defolination. Much of the sight loss in high axial myopia is thought to be due to the damaging effects of the stretching and thinning of the inner parts of the eye. One of the major forces at work in this stretching process appears to be the normal intra-ocular pressure. Genetically weak elements of the scleral wall are prone to thinning and stretching. The adult progression appears to be due to the stretching of the walls of the eye. Unfortunately, this form of myopia frequently progresses in adult life, with small intermittent steps of elongation being observable at any age. In all of these cases, the distant object appears to the eye to be situated at its far point and is therefore in focus on the retina. The defocusing of the retinal image may be corrected by spectacle lenses, contact lenses or by refractive surgery. This is known as the far point of the eye. If objects are brought close to the eye, a point is reached when they come into focus. Distant objects are focused in front of its retina and are thus out of focus. The eye is said to have high axial myopia (nearsightedness). The genetic defects responsible may be transmitted between the generations in a variety of ways, and may produce very different degrees of myopia in different family members.Īn affected individual will show accelerated growth of the size of the eye during the normal growth-periods of childhood and adolescence, so that, by the late teens, or the early twenties, the eye is much longer than normal. This is why the incidence of this condition varies so much between the various ethnic groups. To summarize the course of this condition: It presents for the majority of people, as an inherited genetic condition. It is reported to be the seventh ranking cause of legal blindness in the United Sates of America and the fourth ranking cause in Hong Kong, degenerative myopia is an important world-health issue that has had an unfortunate history of ineffectual treatments that have led most eye specialists to believe that it is something of a "lost cause".Īs a result, this condition, which is responsible for the loss of vision in so many people during the middle years of life and in old age, seems destined to run its natural course, save for attention to correction of the refractive error and the treatment of some of its complications. Degenerative myopia deserves our recognition as one of the truly neglected areas of ophthalmology.
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