Sight from Dog and Dogfish

The cornea of the eye is one part of the body that can be transplanted from one human being to another without touching off the immune reaction or rejection mechanism which dooms most skin and organ grafts. Because of this cornea capability, "eye banks" have helped surgeons restore vision to tens of thousands. But at best the banks have difficulty matching supply with demand, and in many parts of the world, where religious scruples intervene, eye banks cannot even get started. Why not use animal corneas?

Professor Paul Payrau of Paris has been doing just that, he told a World Congress on the Cornea in Washington. First, of course, he tried grafting corneas from animal to animal. He got mixed results, but enough encouragement to try the technique on human patients. Pig corneas were no good because after transplantation they became opaque. But corneas from a large variety of dogs have remained transparent in 50% of Dr. Payrau's cases. Size is unimportant since only a segment of the human cornea is replaced. Dogs' eyes even have an advantage over humans': the dog never suffers from inflammation and scarring of the cornea due to infection with the herpes simplex (fever blister) virus. Human corneas are vulnerable to this virus.

Dr. Payrau has also had some success with calf corneas, though they usually do not retain so much transparency as those of dogs. But his most exotic source of supply is a species of small shark, the lesser spotted dogfish (Scyliorhinus caniculus). Its cornea has the advantage of not swelling in water, which made it attractive to Dr. Payrau for patients whose eyes leak fluid, though it is thin and fragile and retains only moderate transparency.

More work is needed before fish-eye transplants become routine, said Dr. Payrau, but he believes that dog corneas should now be used in emergencies when human corneas are not available.

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