The procedure involves injecting tattoo ink into the white part of the eye (called the sclera) to color the eyeball.
During the procedure, a tattoo artist injects ink just under the surface of the conjunctiva, the clear membrane that covers the white part of the eye, according to the American Academy of Ophthalmology (AAO).
In Gallinger's case, the artist (who also happened to be her boyfriend) injected too much ink in one sitting, used a needle that was too big, made an injection that was too deep and did not dilute the ink with saline as is required, according to Time.
A tattoo on the eyeball can pose serious risks, and the procedure hasn't been studied by eye doctors or scientists, according to the AAO.
In that case, the ink was injected too deep into his eye, and he also developed a bacterial infection from contaminated ink.