PURPOSE: To investigate the risk factors and mechanisms of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK). METHODS: In 5708 eyes of 2927 patients who underwent LASIK, the patient's background, clinical findings, and surgical data were retrospectively evaluated and compared with patients who had DLK and those who did not (non-DLK group). RESULTS: DLK occurred in 46 of 5708 eyes (0.81%). DLK occurred more frequently in eyes operated with the MK-2000 microkeratome (1.1%) than with the LSK-One microkeratome (0.6%; P=.039). Corneal endothelial cell density (2686.8 ± 235.3/mm2) was significantly lower in eyes that developed DLK than in eyes without DLK (2783.8 ± 275.5/mm2; P=.017). The width of palpebral fissure in a normal state and the maximum opening position were significantly larger in the DLK group (10.3 ± 1.9 mm and 18.1 ± 7.2 mm, respectively) than the non-DLK group (8.3 ± 1.6 mm with P<.001; 11.5 ± 2.0 mm with P=.012). CONCLUSIONS: The type of microkeratome, lower corneal endothelial cell density, and larger palpebral fissure were potential risk factors for DLK after LASIK. These factors may be associated with delayed wound healing of the corneal flap margin, resulting in poor sealing of the flap, which may induce the influx of inflammatory cells.
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