Corneal tattooing is an ancient procedure that was first employed by Galen in 129 AD to disguise leucomata of the eye. The list of indications for tattooing of the cornea has decreased over the centuries due to the progress in both keratoplasty and contact lens fitting. However, current indications may include eccentric corneal scars, contact lens intolerance, complaints of visual disability secondary to light scattering (ie, due to an eccentric pupil or large peripheral iridectomy), and for ocular cosmesis in non-surgical eyes.
Historically, there have been two predominate methods for tattooing the cornea: (1) Chemical – a chemical reaction involving precipitated pigment is brought about in the cornea, typically of metallic salts (an example of this is platinum chloride reduced by hydrazine hydrate to platinum black) and (2) coloring – this technique involves the direct introduction of colored pigments into the cornea. A variety of dies have been used in the past including India ink, Chinese ink, Gold dust, lamp black, candle soot, metallic powders, organic dyes, and uveal pigment. Several modifications to the techniques and types of dyes have been made over the decades and we will review a few current techniques, including our own, below.
Pfeiffer et al. report a technique in which the shaft of a 3-edged, spatulated needle (from a conventional 10-0 nylon suture) is covered in ink and sequentially multiple, tangential punctures into the corneal stroma are made. This group advocates the use of commercially available drawing ink for this technique. While successful in some hands, potential problems with this technique include:
- Risk of full thickness puncture through the cornea
- Multiple incisions could activate inflammatory cascade and phagocytosis of the dye, decreasing the duration of results
- Multiple incisions through Bowman’s layer could promote recurrent corneal erosions
- Difficulty in uniform pigmentation
Another group has reported on the use of the Intacs lamellar dissector to create intra-stromal lamellar channels into which commercially available tattoo pigments are injected. However, as discussed above, the limitations of this technique include the difficulty of uniform pigmentation as well as a limitation in surface area available for dying secondary to the size of the Intacs lamellar dissector.
Franks et al. have described a unique solution to visual complaints following the creation of a peripheral iridectomy (PI). In this technique, a keratome is used to create a 2.0 mm intra-stromal corneal pocket anterior to the PI. Following this, filter paper soaked in sterile platinum chloride solution is introduced into the pocket and a reducing agent of hydrazine hydrate is slowly added beneath the filter paper. Excess solution is soaked up by a limbal placed dry weck sponge to minimize conjunctival staining. Symptomatic relief from glare was achieved in this patient with no ocular inflammation or corneal erosion symptoms at 2 months.
Other groups have attempted different variations of lamellar dissection of the cornea followed by intra-stromal dying with various inks. Overwhelmingly, all of these techniques are plagued by a similar limitation: difficulty in accurately delineating the margin of the tattoo bed resulting in an irregular tattoo border and irregular distribution of stain. We have attempted to address this limitation by using the Intralase femtosecond laser to create a lamellar free cap. Next, we carefully apply commercially available tattoo dye to the stromal side of the lamellar cap. Finally, the corneal free cap is replaced on the host cornea stromal bed and a bandage contact lens is placed.
In terms of dye selection, currently most corneal surgeons have used commercially available tattoo pigments including ferric oxide, iron oxide, ferric hydroxide, carbon black, titanium dioxide, and pigment blue 15. However, it must be emphasized that the long-term safety and toxicity of these dyes has not been proven. Additionally, there have been reports that these dyes may contain some harmful substances including arsenic salts, barium, and chlorine. Therefore we recommend the use of these dyes only in blind eyes where less invasive interventions are not an option.
Have a question or comment on this article? Use the "Comment" link above to leave your thoughts, and the author will respond.