PURPOSE: To evaluate endothelial cell trauma by anterior chamber (AC) air bubbles in Descemet stripping automated endothelial keratoplasty (DSAEK). DESIGN: Laboratory investigation. METHODS: Twelve human donor corneas (6 pairs) were sectioned using an automated microkeratome system (Moria ALTK System, Antony, France). One cornea of each pair was mounted on a Moria artificial AC, and an air bubble was injected to fill 40% of the AC. The apparatus was rotated 180 degrees for a total of 50 times to simulate air bubble trauma. The fellow corneas were used as controls. Each endothelial graft was stained with 0.25% Trypan blue for 90 seconds followed by 0.2% alizarin red for 2 minutes, and digital photomicrographs were obtained. Abnormally staining areas indicative of graft injury were removed digitally from the total graft area. The proportion of uninjured corneal endothelium was calculated, and differences were analyzed. RESULTS: In this ex vivo model of air bubble trauma, the proportion of viable graft endothelium after air bubble injury was 79.8 +/- 0.04% (n = 6). The proportion of viable endothelium in the control group was 89.9 +/- 0.02% (n = 6). The statistically significant mean difference of 10.1% (P = .03) is indicative of greater endothelial injury after air bubble trauma. CONCLUSIONS: Using this model, a moderate but significant amount of endothelial cell damage was associated with air bubble trauma compared with the control group. Air bubble trauma may account partially for the loss of endothelial cell density after DSAEK surgery and may impact graft survival.