Corneal Biomechanical Evaluation After Meniscus-Shaped Stromal Lenticule Addition Keratoplasty (MS-SLAK) for Keratoconus

PURPOSE: To evaluate corneal biomechanical changes af- ter meniscus-shaped stromal lenticule addition keratoplasty (MS-SLAK) performed for the treatment of keratoconus.METHODS: This interventional study included patients affect- ed by advanced keratoconus (stage III and IV) who underwent examination with a dynamic Scheimpflug analyzer and non -contact tonometer (Corvis ST; Oculus Optikgerate GmbH) at baseline and 12 months after MS-SLAK. The biomechanical parameters evaluated in this study were integrated inverse radius (1/R), deformation amplitude ratio (DA ratio), stiffness parameter at first applanation (SP-A1), biomechanical intra- ocular pressure (bIOP), central corneal thickness (CCT), and stress-strain index (SSI).RESULTS: Sixteen patients were enrolled in the study. The analysis was ultimately conducted on 15 patients. Compara- tive analyses showed an increase in corneal stiffness as dem- onstrated by a rise in SSI (P < .0001) and SP-A1 (P < .0001) and a decrease in DA ratio (P < .0001) and 1/R (P = .01). A sig- nificant increase in CCT was found (P < .0001). No statistically significant modification was found for bIOP (P = .43).CONCLUSIONS: The corneal biomechanical analyses evalu- ated by the Corvis ST showed that MS-SLAK for advanced keratoconus is able to increase corneal overall stiffness. This result is explained by the significant increase in thickness in- duced by MS-SLAK.