Stromal keratophakia: Corneal inlay implantation

Stromal keratophakia was first performed by Jose Ignacio Barraquer in the 1960s. The refractive lamellar keratoplasty technique was intensely pursued in the 1980s as a method to alter corneal refractive power. However, because sculpting of the donor stromal lenticule and lamellar keratectomy of the recipient's cornea were performed with a mechanical microkeratome, the quality of the cut was inconsistent. Consequently, the refractive outcomes of the lenticule implantation were poor. In addition, epithelial ingrowth, interface scarring, and induced astigmatism were common due to the manual resection. With the advancements of femtosecond laser, we are now able to optically sculpt a refractive lenticule and create an intrastromal pocket for implantation, with greater accuracy and precision compared to manual incisions. The lenticule can be decellularized, cryopreserved, and implanted on a later date to correct hyperopia and presbyopia, as well as to treat corneal ectasia and perforations. In this article, we will review the history of stromal keratophakia and the shortcomings of the previous attempts that led to its abandonment. We will then discuss the reinvigoration of stromal keratophakia with the emergence of advanced femtosecond laser technologies, including the basic science and clinical applications of femtosecond laser-assisted stromal keratophakia, methods to decellularize, cryopreserve and transport the refractive lenticule, lenticule banking, and regulatory framework that oversees the distribution and clinical translation of stromal lenticule implantation.