Purpose: To determine the source of the interface debris that causes the interface inflammation known as 'sands of the Sahara' after laser in situ keratomileusis (LASIK). Setting: Department of Ophthalmology, LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans, USA. Methods: A microkeratome (Automated Corneal Shaper) was used to make a LASIK flap in 8 eyes of 4 rabbits. In 4 eyes, the blade was used directly from the sterile pack; in the contralateral 4 eyes, the blade was cleaned prior to use. In vivo confocal microscopy of the corneas was performed 1 day after surgery. An unused, cleaned blade and an unused, uncleaned blade, as well as blades used in the rabbit eyes, were examined by scanning electron microscopy. Results: Confocal microscopy revealed numerous fragments of debris surrounded by inflammatory cells in the LASIK flap interfaces created by blades taken directly from the sterile package. Interfaces created by the cleaned blades showed only rare, scattered bits of debris. Scanning electron microscopy of the unused blades showed debris on the uncleaned blade removed directly from the sterile package. Conclusion: Post-LASIK interface inflammation may be caused by debris on the microkeratome blade, although other sources are possible. The interface debris and inflammation can be reduced or eliminated by cleaning the microkeratome blade before use.