To compared two sites of air injection to prepare donor lenticules for Descemet membrane endothelial keratoplasty (DMEK).

Fifty-three human corneoscleral buttons from donors aged 4 to 65 years were used. Corneoscleral buttons were placed endothelial side up and a 27-gauge needle was inserted just outside Schwalbe’s line and advanced immediately beneath the endothelium. Air was injected centrally inside the 8-mm zone (group 1) or peripherally approximately 1 mm in front of the limbus (group 2). Air injection was continued to extend the DM detachment as far as possible into the corneal periphery. Comparisons of central versus peripheral air injection were performed for reproducibility, the rate of usable tissue, and the type and diameter of the acquired bubble.

The mean donor age was 38.1±13.2 years. A big bubble was achieved following central or peripheral air injection in all cases. A usable donor lenticule (≥8.0 mm) was achieved in 91.7% of cases in group 1 and 86.2% of cases in group 2 (P=0.67). Both injection sites were comparable with regard to the diameter of the achieved bubbles (9.67±2.12 mm versus 10.06±2.44 mm, respectively, P=0.53), the chance of complete DM detachment (41.7% versus 57.7%, respectively, P=0.26) and the risk of bubble bursting (4.2% versus 6.9%, respectively, P=0.86). The odds of a type-2 bubble increased by 11.74 for peripheral air injections compared to central injections (P=0.01).

Both injection sites exhibited comparable rates of usable donor lenticules. However, peripheral air injection was more likely to yield stroma-free grafts.