In Vivo Confocal Microscopy of Stromal Lenticule Addition Keratoplasty for Advanced Keratoconus

Abstract

PURPOSE: To investigate the in vivo corneal microscopic changes after femtosecond laser–assisted stromal lenticule addition keratoplasty in keratoconus by means of in vivo confocal microscopy. METHODS: Patients affected by advanced keratoconus were included in the study. Negative meniscus-shaped stromal lenticules, produced with a femtosecond laser (VisuMax; Carl Zeiss Meditec) from eye bank corneas were transplanted into a stromal pocket dissected in the recipient cornea at a depth of 120 µm. In vivo confocal microscopy was performed during the 12-month follow-up to investigate changes of the corneal and lenticule structure. RESULTS: Ten patients were enrolled in the study. No changes of the dendritic cell population were documented during the follow-up period. Mild edema and stromal keratocyte activation gradually decreased during the first month. Subbasal nerve density returned to preoperative values after 6 months. Donor-recipient interfaces appeared hyperreflective but gradually improved over time with significantly reduced reflectivity after 3 months. No evidence of stromal inflammatory cell migration or matrix opacification was observed. Endothelial and keratocyte density remained stable over time. A variable degree of stromal radially distributed folds, not visible on biomicroscopy, was observed in the lenticule and in the posterior recipient stroma. CONCLUSIONS: Stromal lenticule addition keratoplasty produces transitory nerve plexus density reduction and minor inflammatory reaction that rapidly decreases during the first month. Donor-recipient interface reflectivity is comparable to a femtosecond laser refractive procedure with no sign of stromal opacification or stromal rejection in 1 year of follow-up. [ J Refract Surg . 2020;36(8):544–550.]

Long-Term Clinical Outcomes of Small-Incision Femtosecond Laser-Assisted Intracorneal Concave Lenticule Implantation in Patients with Keratoconus

“…No evidence of leukocyte infiltration at lenticule-stromal interface was observed during the follow-up. This observation is similar to those of studies by other scholars [ 45 ].…”

Epithelial and stromal remodelling following femtosecond laser–assisted stromal lenticule addition keratoplasty (SLAK) for keratoconus

“…The stromal volume expansion effect at the cone apex, was related to the lenticule implantation itself and the secondary tissue healing response, in addition to the epithelial hyperplasia, to increase the CCT and CTP (+ 67 ± 21 and + 76 ± 26 microns, respectively). Some transient stromal oedema was observed in the first week after surgery, mainly affecting the posterior surface curvature, consistently with the lenticule profile, but, as demonstrated by our previous study that used confocal microscopy for stromal analysis 30 , it rapidly subsided after the first week (Fig. 4B).…”

“…Secondly, the measured values may be influenced by the changes in the recipient stromal layers adjacent to the lenticule interfaces. In fact, extracellular matrix remodelling, triggered by activated keratocytes, is likely to play a significant role in this sense, as documented by in vivo microscopic examination studies 29,30 and animal studies after lenticule implantation for keratoconus 5,6 . Lastly, epithelial remodelling occurring after surgery contributing to the overall corneal thickness increase.…”

Comparison of the Effects of Temperature and Dehydration Mode on Glycerin-Based Approaches to SMILE-Derived Lenticule Preservation

“…Small-incision lenticule extraction (SMILE) is an increasingly common form of corneal refractive surgery wherein an intrastromal lenticule and a side cut are created with a femtosecond laser, yielding an intact refractive lenticule that can serve as a biomaterial with good optical transmittance, desirable mechanical properties, and excellent biocompatibility. 1 The implantation of such stromal lenticules has been successfully implemented in clinical settings to correct for hyperopia, 2 , 3 presbyopia, 4 , 5 and keratoconus, 6 , 7 and for corneal patch grafting as a means of managing corneal perforations and other ocular diseases. 8 – 10 However, fresh lenticules are generally used in these studies, greatly constraining their utility.…”