Femtosecond laser-assisted stromal keratophakia for keratoconus: A systemic review and meta-analysis

Abstract

Purpose Femtosecond lasers have revived the possibility of stromal keratophakia or tissue additive keratoplasty, a technique originally introduced by Prof. Jose Ignacio Barraquer in the 1960s. The surgical technique offers a unique solution to treat keratoconus. In the current study, we reviewed and performed a meta-analysis of the clinical outcomes of the femtosecond laser-assisted stromal keratophakia in the treatment of keratoconus. Methods This is a systematic review and metaanalysis of the estimated outcome difference between pre-and post-lenticule implantations. Results A total of related 10 studies were found in the literature. No studies reported adverse events, such as persistent haze or graft rejection, at last patients' visits. We further narrowed down the article selection in accordance to our inclusion criteria to report the composite outcomes (9 studies) and meta-analysis (4 studies). In the composite analysis, we demonstrated that lenticule implantation in keratoconus and post-LASIK ectasia patients appeared to expand the stromal volume of the thin corneas, flattened the cones, and significantly improved uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and spherical equivalent (SE). The meta-analysis showed that the random estimated UCVA, BCVA, SE and mean keratometry (K m ) differences following the lenticule implantation was -0.214 (95% CI: -0.367 to 0.060; p = 0.006), -0.169 (-0.246 to 0.091; p \ 0.001), -2.294 D (-3.750 to -0.839 D;

Response of the corneal surface changes after stromal lenticule addition keratoplasty combined with cross-linking for keratoconus

“…In general, literature has mentioned three different shapes of lenticules: donut-shaped lenticule (e.g., myopic SMILE lenticule punched at its center), [13] concave-shaped lenticule (e.g., hyperopic SMILE lenticule), [21] and convex-shaped lenticule (e.g., myopic SMILE lenticule). [1,20] Based on a previous study, the concave-shaped lenticule addition seemed to produce a more signi cant impact on Km and SE in advanced keratoconus patients. [21] Donut-shaped lenticule may have a greater effect on attening keratometry.…”

“…Various lenticule implantation with CXL has been desirable to increase the corneal volume and regularize corneal curvature in patients with advanced keratoconus. [1,13,20] The procedure has been shown to result in increased corneal volume and stabilize the cornea and modify the corneal shape. Our study suggests that after SLAK combined with CXL, the posterior corneal surface had a backward shift trend, indicating that this novel technique may have a stabilizing effect on the posterior corneal surface in keratoconus patients.…”

Bioengineered Human Stromal Lenticule for Recombinant Human Nerve Growth Factor Release: A Potential Biocompatible Ocular Drug Delivery System

“…With exquisite precision, during the surgical procedure known as small incision lenticule extraction (SMILE) or Refractive lens extraction (ReLex), an intra corneal stromal lenticule of desired power and shape is sculpted and removed through a small incision ( Reinstein et al, 2014 ). Given that such tissue is generally discarded, recently it has been put to the innovative applications in the treatment of corneal stromal diseases such as keratoconus, hyperopia, and corneal perforation where it physically adds to the thickness and substance of the tissue and alters the shape (curvature) of the cornea ( Pradhan et al, 2013 ; Mastropasqua et al, 2018 ; Riau et al, 2021 ). Although these procedures have shown effective and safe results, immune rejection and inflammation can still occur following allogenic lenticule implantation ( Hashimoto et al, 2016 ).…”

Corneal Stromal Densitometry Evolution in a Clinical Model of Cellular Therapy for Advanced Keratoconus

“…2 Therefore, to avoid these drawbacks, corneal collagen cross-linking, intracorneal ring segments, and more recently lamellar corneal stromal transplantation are alternatively used. 2,5–12…”