To introduce a modification to the big-bubble deep anterior lamellar keratoplasty (DALK) which can decrease the risk of Descemet membrane (DM) perforation during air injection.

After trephination to approximately 80% of corneal thickness, a 27-guage needle (bevel facing downward) was inserted into the stroma peripherally from the trephination site towards the limbus. Air was injected gently into the deep stroma until a big bubble was formed. This technique was performed in 16 consecutive keratoconic eyes undergoing DALK. Additionally, peripheral air injection was carried out in 27 eye-bank corneas using a posterior approach.

In all (100%) eye-bank and 13 (81.3%) live corneas, a successful big-bubble was easily achieved following peripheral air injection. In 2 out of 3 live corneas in which peripheral air injection failed, a big-bubble was successfully formed after air was injected inside the trephination site (standard technique). In one remaining live cornea layer-by-layer stromal dissection was performed after both peripheral and central injections were unsuccessful. No case of DM perforation was encountered in the clinical setting.

Air injection peripheral to the trephination site is a reproducible modification to the standard big-bubble DALK which can decrease the risk of DM perforation and increase the rate of successful big-bubble formation.