Uveitis is an inflammation of the middle layer of the eye, which includes the iris and blood vessels that nourish the other parts of the eye. Common causes of uveitis include viruses, fungi, eye injury, and infections in other areas of the body. If not treated, chronic uveitis can cause permanent vision loss and even blindness.
Dr. Trucian Ostheimer and his fellow colleagues at Wilmer Eye Institute have observed some unique patterns over the past two years: seven separate cases of uveitis accompanied by changes in tattooed skin. In all seven cases, parts of the skin that were covered in the black tattoos became raised and hard at the same time that uveitis symptoms began. Interestingly, when uveitis was treated, the symptoms of raised and hardened skin cleared up as well. Colored tattoos did not have the same effect. Only parts of the skin that were covered by black ink tattoos became raised and hardened.
The conclusion of this study is not that black-ink tattoos cause uveitis. It simply means that more research needs to be done to establish a connection between black tattoos and uveitis. When a doctor diagnosis uveitis, it also may be wise to inquire whether the patient has tattooed skin and whether there have been any changes around the tattoo (Source: Get Eye Smart).