Flap and interface complications in LASIK.

Flap complications using first-generation microkeratomes, such as the Automated Corneal Shaper, were reported in 2.5% (27 of 1,062 eyes). With modern microkeratomes, such as the Hansatome, keratotomy-related complications dropped to 0.16% (46 of 28,201 eyes). Postoperative flap complications, such as flap slippage, occurred in 1.42% (21 of 1,418 eyes), most of them during the first hour after surgery. Interface complications are a new diagnostic entity as the interface between flap and stroma presents an empty space where fluid or cells can accumulate. Diffuse lamellar keratitis usually occurs within the first postoperative days but may also develop later on, triggered, eg, by recurrent corneal erosion. Epithelial ingrowth is a rare complication caused rather by postoperative invasion than by intraoperative implantation, which suggests that the quality of the flap edge and its apposition are very important. Interface fluid is a rare but important phenomenon related to steroid-induced glaucoma but presenting with falsely low tonometry readings.