Meniscus-Shaped Stromal Lenticule Addition Keratoplasty for Corneal Regularization and Thickening in Advanced Keratoconus

Purpose: The aim of this study was to investigate the outcome of the meniscus-shaped stromal lenticule addition keratoplasty (MS-SLAK) in corneal regularization and thickness. Methods: Patients waiting for deep anterior lamellar keratoplasty for advanced keratoconus with an intolerance to contact lenses (CLs) underwent the MS-SLAK procedure by FSL 80 kHz ablation (VICTUS, Technolas Perfect Vision, DE). Customized positive meniscus-shaped stromal lenticules were obtained and implanted. Examination was performed at baseline and at 3-, 6-, and 12-month follow-up and included corrected distance visual acuity both with spectacles and CLs (spectacle CDVA and CL-CDVA), manifest refraction spherical equivalent, slit-lamp examination, anterior segment optical coherence tomography, corneal topography, and in vivo confocal microscopy. Results: Fifteen patients completed the study. Statistical increases in corneal thickness values were found from the first follow-up (P < 0.001). Improvement in the Surface Asymmetry Index (P = 0.04), Symmetry Index (P = 0.02), spherical aberration (P < 0.001), coma (P= 0.18), high-order aberration (P = 0.37), and anterior asphericity index (Q) (P = 0.31) were found at 12 months. At the 12-month follow-up, no improvement were found in spectacle CDVA (P = 0.23); however, all patients reported CL wearing tolerance recovery, and significant improvement in CL-CDVA (P = 0.002) was found. The confocal microscopy at 12 months showed a significant increase in keratocyte density within the lenticule and absence of fibrotic reactions in both anterior and posterior interfaces. Conclusions: MS-SLAK seems to be effective in regularizing the corneal surface as showed by the significant improvement in topographic symmetry indices, coma, and high-order aberration. The corneal regularization is also confirmed by the results in anterior Q and the recovery of the CL wearing tolerance.