The cornea is a transparent layer forming the front of the human eye. It may seem like a simple component of our body, but is actually a highly complex tissue. The cornea contains no blood vessels, and receives its nourishment from tears and the aqueous humor, which is a fluid in the front part of the eye behind the cornea. The cornea consists of five layers of tissues, each with very specific functions. In a healthy eye, a perfect balance is maintained between the fluid (from tears) moving into the cornea and the fluid pumping out of the cornea. The cornea provides protection against dirt, germs, and other particles which can harm the eye. The cornea also plays a key role in vision by helping focus the light that comes into the eye. The cornea is responsible for 65­-75 percent of the eye’s total focusing power. When light strikes the cornea, it bends the light onto the lens. The lens refocuses the light onto the retina, which starts the translation of light into vision. The retina converts the light into electrical impulses that travel through the optic nerve to the brain, which interprets them as images.

The cornea can be afflicted with numerous ailments and diseases. Minor problems are self-correcting, but many require laser surgery, and the more complex problems require corneal transplant surgery. The transplant surgery removes the damaged portion of the cornea and replaces it with healthy donor tissue. We don’t hear as much about them as we do of kidney or liver transplants, but corneas are the most commonly transplanted tissue worldwide, with tens of thousands performed every year. Like organ transplants, the demand far exceeds the supply. One estimate places the demand at 15 million per year.

Artificial corneas exist but they generally do not produce as good a result as transplanted corneas. The challenge with transplants is the potential for rejection of the transplanted tissue. A recent breakthrough may provide the ultimate solution. Researchers at Newcastle University in the United Kingdom have developed a process to 3D print corneas using stem cells as the bio-ink. They have demonstrated they can print a cornea in ten minutes. See the video here. Additional research is required to ensure the necessary quality and patient safety. The researchers believe they can achieve the goals in 5-7 years. This could be a huge breakthrough, especially in lesser developed countries of the world. Read more about 3D printing for healthcare in Health Attitude: Unraveling and Solving the Complexities of Healthcare.