Abstract
Abstract: :
Purpose: Laser in situ keratomileusis (LASIK) is the most common refractive surgical procedure performed worldwide. This study analyzed the light and ultrastructural features of human corneas after LASIK postmortem. Methods:Five corneas of three patients (2 men, 1 woman; average age, 38 years; range 36–46) were processed for light and electron microscopy (scanning [SEM] and transmission [TEM]) postmortem. The average time after LASIK to tissue fixation was 12 months. The average death to preservation time was 6.6 hrs (range, 4–11). The preoperative sphere and cylinder ranged from –2.25 to –7.5 D and 0.25 to 0.75 D, respectively. A Hansatome microkeratome (Bausch & Lomb) was used for flap creation. Results: Light microscopy (LM) showed epithelial edema with no epithelial hyperplasia. The flap–bed interface (FBI) was not visible under LM. SEM showed epithelial cell separation, normal microvilli, but no FBI. TEM displayed numerous activated keratocytes that were elongated and multidirectional in the stroma of the entire flap and FBI. Collagen fiber bundles had an irregular wavy pattern in the flap and FBI compared to the bed. Scattered areas of electron dense material were detected adjacent to activated keratocytes. The keratocyte densities (number of keratocytes/100,000 µm2)were as follows: Conclusion: This study showed that corneal remodeling post–LASIK continues in the flap and in the FBI after 1 year. There is increased cellular activity in the region anterior to the interface as compared to the posterior regions of the corneal interface.
Keywords: cornea: stroma and keratocytes • refractive surgery: LASIK • wound healing