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The outer part of the transplanted human cornea can be left in place, cloudy as it is. Dr. Stone removes most of the thickness in the center, and sets in place a narrow, artificial cornea made of polymethyl methacrylate surrounded by a Teflon skirt (see diagram). The very center of the device is threaded so that it can be moved in or out to adjust its optical characteristics. And if the patient should need further major surgery, the plug can be unscrewed all the way, giving the surgeon direct access to the inside of the eyeball. As for the inside, where the vitreous humor may become clouded or lost through injury, one surgeon is using a synthetic like molasses in January.
Many eye surgeons have learned to correct detachment of the retina by putting a plastic girdle around the eyeball and squeezing it back into shape. And Dr. Stone has implanted plastic tubes in the eyes of glaucoma patients at Massachusetts Eye and Ear Infirmary to remove the accumulation of fluid that causes high pressure inside the eyeball-and eventually blindness.
To replace relatively insensitive tissues and those that are easy to get at, plastic surgeons have a wide choice of materials. They carve Silastic sponge to the shape of a human ear and cover it with skin grafts. For men who have undergone castration because of cancer, there are artificial testicles of the same or a similar material. Artificial breasts are now made of a soft silicone-rubber sack that holds a silicone gel, and they have a backing of Dacron for attachment to the chest wall.
One of the few parts of the anatomy for which the inventive human brain foresees no possibility of a plastic replacement is the brain itself.
*Unknown in nature, these are similar to the innumerable "organic" (carbon-containing) compounds, but have the central chain of carbon atoms replaced by a silicon-oxygen chain. Common sand consists mainly of quartz, which is silicon dioxide.