Purpose: To investigate the association between the use of carboxymethylcellulose sodium 1% (Celluvisc®) (Allergan, Inc.) during laser in situ keratomileusis (LASIK) and the development of diffuse lamellar keratitis (DLK). Setting: Outpatient surgery center, Detroit, Michigan, USA. Methods: In this retrospective case series, the postoperative clinical course and surgical outcomes in 30 eyes of 15 consecutive patients who had LASIK with the use of Celluvisc were reviewed. All patients had primary LASIK, and the incidence and severity of DLK were analyzed. Results: Diffuse lamellar keratitis developed in 24 of the 30 eyes (80.0%) in which Celluvisc was used before the keratectomy (P = < .0001, Fischer exact test). Sixteen eyes (66.7%) had stage 1, and 8 (33.3%) had stage 2. Diffuse lamellar keratitis was diagnosed in most cases (91.6%) on postoperative day 1. All inflammation resolved after treatment with intense topical corticosteroids. Conclusions: Celluvisc used immediately before the keratectomy in LASIK was highly associated with the development of DLK.