refractive surgical problem
Mild corneal haze is relatively common after LASIK and has several possible causes, including debris and diffuse lamellar keratitis (DLK). In contrast, the frank corneal scarring seen here is rare. Central corneal scarring after LASIK happens only when Bowman's layer has been violated in the central cornea during the microkeratome pass. In this case, it is likely that the microkeratome made extremely thin flaps in each eye. These flaps were probably mostly epithelium with tags of attached Bowman's layer. When the flaps were reflected back, the surgeon inadvertently lasered the remaining areas of Bowman's layer, causing patchy scarring. This explains the epithelial defects postoperatively as the epithelium sloughed. The surgeon should have noted the thin flaps and shiny tags of Bowman's layer on the bed and aborted the ablation.
It is curious that this happened in both eyes in this case. I have seen this complication before when the surgeon was using the older model Chiron Automated Corneal Shaper originally used for automated lamellar keratoplasty (ALK). It came with a number of plates of varying thickness. It is likely that the surgeon's assistant or the surgeon placed the 60 μm plate instead of the 160 μm plate in the microkeratome. This creates a flap that is approximately the thickness of the epithelium, leaving multiple tags of Bowman's layer on the bed.
Treatment of this complication is extremely difficult. Phototherapeutic keratotomy can remove some haze and possibly reduce some irregular astigmatism. In general, however, PTK is unsuccessful in patients with corneal scarring associated with tissue loss. Microkeratome lamellar keratoplasty removes the opacity but does not correct irregular astigmatism because the resected lamella is of uniform thickness, leaving the irregularity in the bed. I would not recommend microkeratome lamellar keratoplasty. The 2 remaining alternatives would be PKP or a deep manually dissected lamellar keratoplasty. One of these procedures will be necessary for visual rehabilitation.© 2001 by Lippincott Williams & Wilkins, Inc.