Myopic macular degeneration is not commonly known in the U.S. even though it is the 7th highest ranking cause of legal blindness. In other parts of the world, such as Japan and China, it is the second highest cause of legal blindness. In addition, people of Jewish and middle eastern extraction are greater risk of developing the condition.
What is It?
Myopic macular degeneration (MMD) arises primarily from genetic abnormalities. 30% of all cases were present at birth; 60% of all cases develop before the child is 13. It often continues to worsen, becoming quite severe myopia by the late teens or early 20s and by 60, 50% of MMD patients are legally blind.
The condition is caused by an gradual and significant elongation of the eyeball with a resulting high degree of myopia by late teens to early twenties. The eyeball continues to elongate and the walls of the eye stretch causing the sclera and retina to thin. The patient is at increasing risk of retinal holes, tears, detachment, lattice degeneration, dry and wet forms of macular degeneration. Scarring or neovascularization occurs at the macula. Staphylomas can form behind the macula distorting it. The cornea becomes thicker and more rigid.