Purpose: To investigate the feasibility of intrastromal lenticule insertion to restore corneal shape in a model of ectatic human cornea.
Methods: For this experimental ex vivo study on 34 human corneas unsuitable for transplantation, 17 corneas were thinned by decentralized posterior excimer laser ablation to 200 μm thickness and 6.5 mm diameter and then inflated up to 100 mm Hg to expose the ectasias (recipient corneas). Pachimetry and topography were obtained. Stromal lenticules of the same diameter and thickness as the ectasias were shaped with a femtosecond laser from the remaining 17 donor corneas. An intrastromal pocket was created with femtosecond laser within the ectatic recipient corneas and the donor lenticule was inserted inside it. Changes in corneal architecture and profile were evaluated by means of corneal topography and anterior segment optical coherence tomography.
Results: All stromal lenticules were successfully implanted. Tomography confirmed regularity of the lenticule profile within the stromal pocket. Corneal thickness was significantly increased after the procedure (P < 0.0001). Maximal posterior elevation from the best-fitted toric ellipsoid was significantly reduced (P < 0.0001). Significant flattening of posterior K1 and K2 was also obtained (P = 0.041 and P = 0.004, respectively). Anterior and posterior astigmatism, anterior and posterior asphericity, and spherical aberration did not differ significantly after the procedure.
Conclusions: Femtosecond laser-assisted stromal lenticule addition is feasible for restoring corneal thickness to an ectatic area and for regularizing posterior corneal elevation. The technique opens new perspectives for the treatment of corneal ectasias.
Keywords: Additive keratoplasty; Ectasia; Ex vivo model; Femtosecond laser-assisted surgery.