Corneal tattooing is tattooing of the cornea of the human eye. It is done for esthetic reasons but also for medical reason – to improvement the sight of a patient in case of injury to iris or to alleviate glare, halos, ghost images or light sensitivity of the eye.
Galen, a physician from the 2nd century Greece during the Roman Empire, was the first to mention corneal tattooing. This was done in an attempt to mask the leukomatous opacities of the eye and give the eye more natural look. The physicians of that time would first cauterize the corneal surface with a heated stilet (a slender medical probe) and then apply the dye to the eye made of powdered nutgalls and iron (so called iron gall ink). The same procedure is later mentioned by Aetius (a Byzantine physician and medical writer) in 450 AD. The next time we heard about corneal tattooing was in 19th century. In 1869, oculoplastic surgeon Louis Von Wecker (also known as De Wecker) invented the new method. He anesthetized the eye with cocaine and covered it with a thick layer of ink (he used e black ink, India ink, or China ink for this). He would then insert the ink into the cornea by piercing the cornea with a grooved needle. Corneal tattooing was very influenced by this but it was improved further. Taylor used a bundle of needles instead of just one needle to speed the process up. Nieden invented in 1901 a tattooing pen the worked as a fountain pen. Armaignac also a physician, used a funnel that created a perfectly round pupil.
Many different methods exist today with that use different techniques and instruments. Some still use a hundred year old method of covering the cornea with ink and inserting the needle to bring the ink inside. Some use three-edged spatula needle covered with ink while other inject the eye first with a needle and then rub in the ink with a Daviel curet. As for ink, India ink is still used along with powdered metallic colors, organic dyes, and even the pigment from animal eyes.
There is also scleral tattooing - tattooing over the white of the eye. It is done by injecting the ink under the surface of the white of the eye by needles as in classical tattooing or by a syringe filled with an ink solution.
As all things, corneal tattooing has its advantages and disadvantages. Advantages are returning of the near-natural look of the eyes in case of corneal opacities and short recovery time. Disadvantages are that performing the procedure is not easy and there are risks. People can go blind if they see before that if ink covers the whole eye because procedure is very difficult to perform precisely. Finished result may not be perfect and tattooing must be done again. Tattoo can feel like there is something in the eye and can produce redness. Tattoo can also fade in time. Instead of tattooing corneal grafting, keratoplasty techniques, and tinted contact lenses can be used.