Recent press and meeting reports have described corneal tattooing as a potential solution for poor vision caused by injuries to or disease of the iris, up to and including total aniridia.
It is probably important to realise at the start that corneal tattooing is used for people with traumatic aniridia caused by injury to a previously healthy eye. It is not currently suitable for people with genetic aniridia.
Corneal tattooing for cosmetic purposes has been practised for nearly 2000 years, using the traditional method of needles and ink. Not surprisingly, it can be a painful procedure with some risk of longer term eye damage. More recently, the technology used in laser eye surgery (e.g. LASIK) has been used to improve corneal tattooing in clinical situations.
Laser eye surgery comes in various forms but typically requires the use of a laser to cut a flap under the epithelial surface and remodel the shape of the cornea to cure short-sightedness or astigmatism by changing the corneal shape.
In laser-enabled tattoo procedures, small pockets are created by laser below the cornea surface, and these can be filled with ink to cover over gaps in the iris and prevent glare and other problems associated with iris injury or defects. It can also be used for covering corneal scars. Patients report almost immediate improvement in glare, and if ink is used to match the colour of the remaining or original iris, the tattooed segment of cornea may be virtually invisible from a metre or two away.
The problem for people with genetic aniridia is that the cornea is already fragile and susceptible to damage. Most people with PAX6-related aniridia (including patients with WAGR syndrome) will experience some form of corneal problems in adult life. Aniridic or aniridia-related keratopathy (ARK) is the cornea surface wearing out, leading to scarring and some level of loss of vision. The PAX6 -aniridic cornea easy to damage and not good at repairing that damage.
Just as laser surgery and full corneal transplants are therefore not recommended for people with genetic aniridia, corneal tattooing is currently a no-no as well. The risks of permanent scarring are probably just too great.
Nevertheless, we continue to research the causes of corneal degeneration in aniridia, and work towards better ways of managing or curing that degeneration. It’s not impossible that in the future some form of cosmetic corneal surgery or inking will be possible for people with aniridia.