It is obvious that this disease is caused either by excessive secretion in the eye, or by obstruction in its outlets, or both.
Hippocrates applied the term glaucoma to all opacities behind the pupil. Taught by dissection, Brisseau1 was the first to announce in 1709 that, while cataract was an opacity of the lens, glaucoma was a similar affection of the vitreous humor; therefore, no operation could afford relief. Mackenzie early in the last century recognized the disease as one of pressure, stating that:2
A morbid secretion, of the origin of which we can give no accurate account, fills the cavity of the retina, but, like other morbid productions, is not furnished with the apparatus of removal, necessary for keeping its quantity in equilibrio. Hence the unnatural firmness of the glaucomatous eye, a symptom that often increases to such a degree that the organ is felt to be