Which of following, if true, most helps to explain the low rate glaucoma-related blindness among patients who had the surgery? A. Glaucoma-related blindness is no more common among patients who have had only the surgery than it is among patients who had the surgery after using the eyedrops B. Doctors rarely recommend the surgery for glaucoma patients who have already started the traditional course of treatment C. There is no known physiological cause of glaucoma other than increase in pressure inside the eye D. A significant percentage of the people for whom the eyedrop treatment has been prescribed fail to follow the prescribed daily regimen, because the eyedrops have unpleasant side effects. E. The eyedrops traditionally prescribed to treat glaucoma are normally prescribed to treat other disease of the eye.