Preservation and Reuse of KLEx Lenticules: From Biobanking to Therapeutic and Refractive Innovations

Stromal keratophakia was first introduced by Jose Ignacio Barraquer in the 1960s as a refractive procedure involving the implantation of a stromal lenticule into a lamellar keratectomy bed of a recipient cornea. By increasing central corneal thickness, the added lenticule induced steepening of the anterior corneal curvature, thereby increasing the refractive power. However, due to the technical limitations of the mechanical microkeratome and the use of cryolathed tissue, early clinical outcomes were often inconsistent and included risks of stromal necrosis, epithelial ingrowth, induced astigmatism, slow visual recovery, and corneal haze. Despite these limitations, Barraquer's law of thickness laid the groundwork for modern refractive surgery, including Laser-In Situ Keratomileusis (LASIK). The advancement of femtosecond laser technology has enabled the creation of precise and accurate refractive lenticules, stromal flaps, and pockets. This, in turn, has renewed interest in stromal keratophakia and facilitated the emergence of keratorefractive lenticule extraction (KLEx) procedures, through which stromal lenticules are obtained. These lenticules can be preserved and repurposed for various therapeutic and refractive applications. In this review, we provide a comprehensive overview of KLEx-derived lenticule processing and biobanking, their reuse for hyperopia and presbyopia correction, and their therapeutic potential in stromal thickness restoration, cell-based tissue engineering, drug delivery, corneal structural and macular hole repair, and glaucoma drainage tube coverage.