Optical coherence tomography of Descemet membrane separation by the big bubble technique

PURPOSE: To image Descemet membrane separation by the big bubble technique in human corneas by using anterior segment optical coherence tomography (OCT). METHODS: Five human corneoscleral rims were placed on an artificial anterior chamber and partially trephinated. A 23-gauge needle was inserted into the stroma under slit-lamp control and air was injected. The procedure was continuously imaged by anterior segment OCT. RESULTS: In all corneoscleral rims, a big bubble was created. The spread of air seemed to follow the interlamellar spaces without crossing lamellae. It involved mainly the inner layers of the stroma while sparing the outer 212 +/- 41 microm of the cornea (range, 168-271 microm). Intrastromal pressure build-up forced air above the Descemet membrane, creating tiny air bubbles of approximately 355 +/- 111 microm (range, 210-560 microm). When the pressure inside those bubbles reached a certain level, the bubbles spontaneously coalesced to form a big bubble. CONCLUSIONS: OCT is useful in imaging intracorneal air spread. The main obstacle to creating a big bubble is the impermeability to air of the imperforated posterior stromal lamellae.