Fresh Human Myopic Lenticule Intrastromal Implantation for Keratoconus Using SMILE Surgery in a Long-term Follow-up Study: Ultrastructural Analysis by Transmission Electron Microscopy

Abstract

PURPOSE: To investigate new intrastromal histological structures that develop after myopic human lenticular implantation in keratoconus with femtosecond laser–assisted small incision lenticule extraction (SMILE) surgery using transmission electron microscopy. METHODS: Sixty eyes with advanced keratoconus indicated for corneal transplantation were included in this study. Fresh myopic lenticular implants were placed in all eyes through SMILE surgery. Lenticular implants were extracted from patients with myopic refractive errors of the cornea, untreated keratoconus, and treated keratoconus following 1, 2, and 3 years of surgery. These five lenticular samples were examined under the electron microscope and compared. RESULTS: Disorganized and thinned collagen fibers were observed in the stroma with degenerative stromal cells (telocyte-like cells and keratocytes) in the keratoconic cornea. Apoptotic bodies and cell debris were easily observed near the disorganized fibers. In contrast, the myopic refractive error of the control and treatment groups demonstrated well-organized parallel lamellar structures. Healthy keratocytes and telocyte-like cells were observed in samples obtained 1, 2, and 3 years after lenticular implantation. Thus, telocyte-like cells may be activated by appropriate stimuli, such as stem cells, and be involved in stromal regeneration. CONCLUSIONS: Fresh myopic intrastromal lenticular implantation is a safe, economical, and reliable technique that leads to increased corneal thickness, improved visual acuity, and the regeneration of healthy keratocytes and telocyte-like cells that are involved in stromal regeneration. [ J Refract Surg . 2022;38(8):520–528.]

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK: a case series

“…However, SLAK under an existing corneal flap theoretically shared common risks with FS-LASIK surgery, which includes flap-related complications, epithelium ingrowth, and lenticule dislocation [16,25] . In recent years, an alternative surgical method to implant the lenticule within a corneal stromal pocket created by femtosecond laser for the treatment of keratoconus has been explored [11][12]14,16,[26][27][28][29] . Compared with our cases, they may show potential advantages of reducing the risk of lenticule dislocation as it is more firmly implanted [26] .…”

Update on corneal crosslinking for keratoconus and corneal ectasia

“…Once the cornea is stabilized with crosslinking, further reshaping procedures can be performed sequentially or simultaneously to improve a patient's vision and corneal topography. These procedures include additive procedures such as Corneal Tissue Addition Keratoplasty (CTAK) [24 ▪ ], Femtosecond Intrastromal Lenticular Implantation (FILI) [25], Corneal Allogenic Intrastromal Ring Segments (CAIRS) [26], and intracorneal ring segments (e.g. Intacs, Ferrara rings) [27].…”

A Bioengineering‐Regenerative Medicine Approach for Ocular Surface Reconstruction Using a Functionalized Native Cornea‐Derived Bio‐Scaffold

“…[64,65] However, this additional processing might not be necessary because mid-to-long term follow-up have not reported any adverse immunological events with unmodified lenticules in recipients. [66][67][68][69] Certainly, immune cells have been detected in fresh lenticules compared to few or none in preserved specimens. [70] We confirmed this notion by identifying a population of CD45 + leukocytes within lenticules, further specifying them as CD14 + macrophages (Figure 5a, first-third columns).…”