In vivo confocal microscopic evaluation of corneal wound healing after femtosecond laser-assisted keratoplasty

Abstract

Background and objective: To evaluate corneal wound healing after femtosecond laser-assisted keratoplasty (FLAK) using in vivo confocal microscopy (IVCM).

Patients and methods: Prospective, interventional, consecutive case series of 17 eyes after mushroom-shaped FLAK. IVCM was performed preoperatively and at 1, 3, 6, and 12 months postoperatively to assess wound healing.

Results: Mean keratocyte activation grade increased from preoperative levels to 1 month postoperatively in both the central (0.41 ± 0.62 to 1.73 ± 1.03) and peripheral (0.47 ± 0.52 to 1.57 ± 1.09) cornea, then gradually decreased through 12 months. Dendritic cells increased from preoperatively to 1 month postoperatively in both the central (0.71 ± 0.83 to 1.33 ± 0.98) and peripheral (0.79 ± 0.70 to 1.42 ± 0.90) cornea, then gradually decreased until 6 months postoperatively. Stromal reinnervation was 1 month postoperatively in 8 patients (50%). By 12 months, sub-epithelial nerves were observed centrally in 5 patients (45.5%).

Conclusion: IVCM after FLAK shows an initial increase in keratocyte activation and dendritic cells that decrease over time. Corneal reinnervation is seen as early as 1 month postoperatively.

Figure 1

Keratocyte activation. In vivo confocal microscopy standard images used for grading keratocyte activation. Grade 0: 0–25% of keratocytes with visible cell processes; grade 1: 25–50% activation; grade 2: 50–75% activation, grade 3: 75–100% activation.

Figure 2

Dendritic (Langerhans) cells. In vivo confocal microscopy standard images used for grading dendritic cells. Grade 0 (not shown): no dendritic cells in the basal epithelium; grade 1: 1–5 cells; grade 2: 6–20 cells; grade 3: >20 cells.

Figure 3

In vivo confocal microscopy standards used for determining the presence of (A) subepithelial corneal nerves, (B) needle-like opacities, and (C) microdots.

Figure 4

Corneal Reinnervation. Kaplan-Meier survival curves of central (top) and peripheral (bottom) corneal reinnervation showing stromal nerve regeneration preceding presence of subepithelial nerves. Of note, stromal nerves were observed as early as 1 month after surgery.

Figure 5

Corneal Nerve Morphology. In vivo confocal microscopy shows irregular morphology of the nerves regenerating after femtosecond laser-assisted keratoplasty. Subepithelial nerves A. preoperatively and B. 1 year postoperatively show marked reduction of nerve density, thinner diameter, and increased tortuosity. Stromal nerves C. preoperatively and D. 1 year postoperatively also show thinner diameter and increased tortuosity.