People who have minus number glasses more than 6 diopter in power are said to have high or pathologic myopia. The glass number of such patients may even be as high as 15 to 20 diopters. The eyeball in such cases is enlarged leading to thinned out coats of the eyeball so the central area may be very weak (chorioretinal degeneration) leading to poor vision. The retina in these eyes is weak in the periphery also and usually has some degeneration, atrophic holes, or even retinal tears. These retinal holes or tears may sometimes lead to a serious condition of retinal detachment, leading to sudden loss of vision, and may require major surgery urgently to settle the retina.