Corneal lamellar refractive surgery for myopia reduces the risk of corneal haze but
adds to the risk of flap complications. We retrospectively determined the incidence
of flap complications in the initial series of eyes undergoing lamellar refractive
surgery by one surgeon. We assessed the incidence of flap complications overall, the
trend in these complications during the surgeon's learning curve, and the impact of
the complications on best spectacle-corrected visual acuity.
Charts of the first 1,019 eyes that underwent myopic keratomileusis in situ or laser
in situ keratomileusis were reviewed for flap complications and visual outcome.
Of the 1,019 eyes, 490 eyes underwent myopic keratomileusis in situ, and 529 eyes
underwent laser in situ keratomileusis. Eighty-eight (8.6%) of 1,019 eyes had flap-related
complications. Six eyes had two complications. Intraoperative complications included
irregular keratectomy in nine eyes (0.9%), incomplete keratectomy in three eyes (0.3%),
and a free cap in 10 eyes (1.0%). The incidence of intraoperative complications was
six (6.0%) in the first 100 consecutive eyes, 14 (2.3%) in the next 600 consecutive
eyes (P = .04, chi-square test), and one (0.3%) in the last 300 eyes (P = .03, chi-square
test). Postoperative complications included displaced flaps that required repositioning
in 20 eyes (2.0%), folds in the flap that required repositioning in 11 eyes (1.1%),
diffuse lamellar keratitis in 18 eyes (1.8%), infectious keratitis in one eye (0.1%),
and epithelial ingrowth that required removal in 22 eyes (2.2%). The incidence of
flap displacement and folds in 200 eyes in which we irrigated under the flap and allowed
it to settle without further manipulation averaged 8.5%, whereas the incidence in
other groups of 100 consecutive eyes averaged 0.8% (P < .00001, chi-square test).
The incidence of diffuse lamellar keratitis was 0.2% in eyes that had undergone myopic
keratomileusis in situ and 3.2% in eyes treated by laser in situ keratomileusis (P
= .0003, chi-square test). No eye lost 2 or more lines of best spectacle-corrected
visual acuity because of flap complications.
Flap complications after lamellar refractive surgery are relatively common but rarely
lead to a permanent decrease in visual acuity. Physician experience with the microkeratome
and with the handling of the corneal flap decreases the incidence of flap complications.