Our thesis, inspired by the experience and teaching of Paul A. Chandler, is that after the optic discs have developed cupping and atrophy from elevated intraocular pressure they tend to become abnormally vulnerable and, in some cases, may continue to deteriorate even if the intraocular pressure is brought to the teens. At this stage they behave the same as in eyes with so-called low-tension glaucoma, which have developed progressive cupping and atrophy with pressures always in the teens. In either case, we find that the progression of cupping and field loss can be stopped by reducing the intraocular pressure to lower levels, preferably to 10 mm Hg or less. We have found that such low pressures are most reliably attained by surgery, using a special technique we call the shell tamponade filtration procedure, which involves the use of a glaucoma shell in conjunction with standard (full-thickness sclerostomy) filtration operations and certain specific operative and perioperative maneuvers. We present nine case reports illustrating our thesis. Glaucomatous cupping and loss of visual field were progressing relentlessly at normal pressures in each case. This progressive deterioration was shown to be arrested by reduction of the pressure to less than 12 mm Hg in 13 eyes.