Chad Kister releases some of his glaucoma records:
Kister was diagnosed with severe glaucoma in 1990, with pressure readings in the mid-30s. Because he is allergic to nearly every glaucoma medicine, making them very harmful and ineffective in treating the number one cause of blindness, doctors in 1990 said that he would likely go blind in 5-10 years.
Through intensive study and the finding of a medicine that he is not allergic to, he has retained his eyesight. Note that these were written after he found a successful medicine (not Timoptic, which he is allergic to).