Aim To determine if residual corneal stroma remains on the recipient posterior lamella in big-bubble deep anterior lamellar keratoplasty (DALK).

Methods Pneumodissection using the big-bubble technique was carried out on eye-bank corneas mounted on an artificial anterior chamber. Samples that had a successful big-bubble formation were sent for histological evaluation to determine if any residual stroma remained on the Descemet membrane (DM).

Results Big-bubble formation was achieved in 32 donor corneas. Two distinct types of big-bubble were seen: the bubble had either a white margin (30 corneas) or a clear margin (two corneas). The posterior lamellae of all the white margin corneas showed residual stroma on DM with a mean central thickness of 7.0 μm (range 2.6–17.4 μm). The clear margin corneas showed no residual stroma on DM.

Conclusion It should no longer be assumed that big-bubble DALK, where the bubble has a white margin, routinely bares DM. True baring of DM may only occur with the less commonly seen clear margin bubble.