'Expanding bubble' modification of 'big-bubble' technique for performing maximum-depth anterior lamellar keratoplasty

To describe a new technique for performing maximum-depth anterior lamellar keratoplasty.

This was a case series study using a novel method. We introduce and describe a new sign (sunny-side up sign) that reveals the presence and extent of the air bubble at the Descemet membrane (DM)-stroma interface. We also report a novel technique to expand the bubble by injecting viscoelastic material into the bubble cavity and to excise the stromal tissues within the trephination area almost completely. The follow-up period ranged from 12 to 16 months. In all patients we recorded the best spectacle-corrected visual acuity, keratometry, and endothelial cell count preoperatively and postoperatively and the air bubble diameter using the sunny-side up sign.

In eight of nine patients, a big bubble formed. The size of the air bubble ranged from 2 to 7 mm. All the bubbles were expanded to 8 mm and the bare DM throughout the trephination area was obtained in all cases. The postoperative mean keratometric readings were reduced compared with the preoperative mean keratometric readings. The BSCVA was increased postoperatively compared with the preoperative acuity. The difference between the preoperative and postoperative endothelial cell counts was not statistically significant.

The early outcomes in our series using the expanding bubble technique suggest that it is safe and easy in performing maximum-depth anterior lamellar keratoplasty.