The role of epithelial defects in intralamellar inflammation after laser in situ keratomileusis

A single factor responsible for diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) has not yet been identified. Various theories have been proposed to explain what may trigger this condition. We evaluated the role of epithelial defects in interface inflammation and assessed the outcome of eyes with DLK with and without epithelial defects.

We reviewed the records of all patients with DLK after LASIK performed at the Toronto Gimbel Eye Centre between September 1999 and May 2000. Patients with other epithelial problems, such as punctate epithelial erosions, were excluded. Patients with an epithelial defect and interface keratitis (group 1) were treated with a bandage contact lens and topical steroid therapy; those with interface keratitis alone (group 2) were treated with topical steroid therapy. Variables examined included the onset and duration of DLK, uncorrected visual acuity, best corrected visual acuity, refractive outcome and retreatment rate.

A total of 1,436 LASIK procedures were performed during the study period. Thirteen patients (20 eyes) had DLK after LASIK, in all cases of the sporadic type (i.e., nonepidemic). Of the 20 eyes, 8 had an epithelial disturbance. All the patients were followed for at least 3 months. Three eyes (37.5%) in group 1 had uncorrected visual acuity before retreatment of less than 20/25, compared with 2 eyes (16.7%) in group 2. The mean postoperative spherical equivalent was significantly higher in group 1 than in group 2 (-0.60 vs. -0.02 dioptres) (p = 0.01). The retreatment rate was 37.5% (3/8) in group 1 and 16.7% (3/12) in group 2, a nonsignificant difference. After retreatment the uncorrected visual acuity was 20/20 or better in all cases. There were no cases of recurrence of DLK after retreatment.

Eyes with interface keratitis and an epithelial defect have a larger deviation from emmetropia before retreatment than eyes with interface keratitis alone. Patients with epithelial defects intraoperatively or who are at risk for such defects postoperatively must be monitored carefully, as they may be at increased risk for DLK.