Johann Sebastian Bach (1685–1750) composed over 1000 works, sired 20 children and was famously blind. New research in the journal Acta Ophthalmologica suggests the eventual cause of his blindness was severe glaucoma following cataract surgery.
Early accounts attributed his failing sight in his mid sixties to overstressing his vision in poor illumination. He was convinced to have cataract couching by a British surgeon (where the cataract is simply pushed into the back chamber of the eye). Although his vision improved initially he was confined to bed by excruciating pain in the eyes and body. He died less than 4 months after this procedure.
A common complication of this kind of early surgery is that the eye begins to reject the cataract which has been forced into the back of the eye as foreign material and inflammation takes hold. This in turn can cause a form of glaucoma which can cause severe pain and eventual blindness.
Nowadays cataracts are completely removed during surgery and replaced with a man made implant to correct the vision.