[Annular keratopigmentation (PresbyRing®) for treating presbyopia: postmortem animal feasibility study]

Annular keratopigmentation (PresbyRing(®)) is a new technique which creates an intrastromal ring centered on the visual axis, using a femtosecond laser, into which a black or a colored pigment is then injected. The internal diameter of the ring is dimensioned so as to create a pinhole and improve the near and intermediate vision of the non-dominant eye while only slightly altering the distance vision of that eye.

We used five pig eyes for our postmortem feasibility study; all five were treated with the Intra Corneal Ring program (ICR(®)) of the Visumax(®) laser. The dye used (Biochromaderm(®)) has EU approval.

Spectral domain OCT examinations demonstrate complete opacity of the dye. Histological analysis with hematoxylin and eosin stain highlights a continuous pigmented layer located along the incision, which does not diffuse in the adjacent stroma. The possibility of rinsing the dye must be confirmed by future in-vivo animal studies.

To our knowledge, this study represents the first experimental attempt to combine two ideas which did not appear to have anything in common: the creation of an intracorneal pinhole to treat presbyopia, and corneal tattooing. The first postmortem feasibility study in animals for annular keratopigmentation (PresbyRing(®)) gave encouraging results. It must be confirmed by in vivo animal studies, and ultimately in humans.