Rosenwasser DALK Cannula for the "Big Bubble" technique George Rosenwasser, MD of Hershey, Pennsylvania designed this new cannula for the "Big Bubble" technique in Deep Anterior Lamellar Keratoplasty (DALK). The beveled distal tip of the cannula is easily introduced into the channel created with a dissector. Once in place, the "cobra-shaped" head seals the channel and aids in the infusion of air through its posterior 0.2mm port, thereby pneumatically dissecting the stroma from the underlying Descemet's membrane. This 27 gauge cannula is flattened and vaulted to conform to the cornea and is 8mm long from the angle to the tip.