Corneal lamellar flap retraction after LASIK following penetrating keratoplasty.

To the Editor: We read with great interest the article entitled BCorneal Lamellar Flap Retraction After LASIK Following Penetrating Keratoplasty^ by Chan et al. We have also experienced a similar outcome in a 48-year-old male patient after microkeratome cut for the reduction of high astigmatism in an eye with a corneal graft 1 year after penetrating keratoplasty for healed keratitis. All sutures were removed 2 months before the microkeratome cut. The uncorrected visual acuity (UCVA) was 3/60, and the best-corrected visual acuity (BCVA) was 6/36 (correction: +1.5 D sphere/j10.5 D cyl 160). The keratometry was 39.50 165/52.0 65, and the central corneal thickness (graft) was 526 Km. Slit-lamp biomicroscopy revealed the presence of a clear graft. A Hansatome (Bausch and Lomb, Salt Lake City, Utah) with a 180-Km head was used with a suction ring of 8.5 mm to create a lamellar corneal flap. The flap was lifted, floated, and then repositioned without performance of laser ablation. A bandage contact lens was placed over the cornea. Postoperatively, the patient was prescribed topical ofloxacin 0.3% and topical dexamethasone phosphate 0.1% and lubricants (polyvinyl alcohol and povidone) QID each. On the first postoperative day, on slit-lamp biomicroscopy, the flap was retracted, and the margin was raised inferotemporally, forming a step, although it was well apposed in other areas. On the second postoperative day, partial melting of the flap was noted along the raised margin (Fig. 1). The frequency of lubricants was increased to once hourly. On day 5, partial epithelialization was noted from the edge of the melted area. At 1 week postoperatively, the area of the flap retraction was totally epithelialized, and the bandage contact lens was removed. There was epithelial ingrowth in the interface of 1.2 mm along the same margin (Fig. 2). The keratometric astigmatism at 1 week was 7.75 D (K = 43.25 160/51.0 70). The uncorrected visual acuity was 6/60, and the best corrected visual acuity was 6/18 with +2.0 D sphere/j5.0 D cyl 160. He was prescribed topical fluorometholone 0.1% twice a day and lubricants 4 times a day. At 1-month and 3-month followup, there was no increase in the epithelial ingrowth, and the flap was well apposed. The uncorrected and the best corrected visual acuity remained the same as on day 7. The creation of a lamellar corneal flap by microkeratome as the first stage in a 2-step LASIK procedure is effective in reducing the keratometric astigmatism following penetrating keratoplasty. There was marked reduction in the keratometric astigmatism in our patient after the microkeratome cut; however, the flap was retracted in the steeper axis. Chan et al have attributed the flap retraction to the edema of the flap during its creation. We hypothesize that in a corneal graft, a suture that is too tight in 1 meridian can pull up the graft tissue in that axis. The tissue remains pulled up even after complete wound healing. The lamellar cut made by the microkeratome releases this pull, and the flap straightens up and retracts, creating a step at the margin. As this part of the flap remains redundant, it melts. During epithelial healing in such cases, there is risk of progressive epithelial ingrowth in the interface. Although in this case there was no increase in epithelial ingrowth at subsequent follow-up visits after complete healing, a regular and meticulous follow-up is essential to look for the progression of the epithelial ingrowth.