Myopia, commonly known as near sightedness, is a refractive defect of the eye. People with myopia can see objects close to them clearly but objects far away are blurred. In a normal eye, the light focuses onto the retina perfectly but in a myopic eye, the light is focused in front of the retina in the vitreous. This is caused by the eye being too long or the cornea having too high of a refractive power. In most cases, this can be corrected with glasses, contact lenses or LASIK surgery.
Myopia can occur in several different forms: simple, congenital and degenerative. Simple myopia is a normal chance variation in the refractive error of the eye. Congenital myopia tends to be stationary and nonprogressive. Degenerative myopia is characterized by a prescription greater than -6 D, a long eye and progressive choroidal degeneration in the back of the eye.
Myopic Degeneration is the 7th leading cause of blindness. It is associated with retinal changes which progress rapidly. In myopic degeneration the vitreous liquifies and can cause a posterior vitreous detachment as well as rings or crecents around the optic disc where the surrounding tissue has atrophied. Lattice degeneration (oval or linear patches of retinal thinning) in the peripheral retina and thinning of the retina pigment epithelium is common as are lacquer cracks (breaks in Bruch's membrane and the choriocapillaris leading to atrophy of the choriod). In addition, the optic disc often tends to appear tilted or malinserted. The streching of the sclera (because of lengthening of the eye) can also lead to weaknesses in the sclera and subsequent bulging out. Because the eye continues to grow longer and forms so many weaknesses in the structures of the eye itself, degenerative myopia patients are at a high risk for retinal detachments and macular changes such as neovascularization (abnormal new blood vessel growth) as seen in macular degeneration.
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