Using a "small bubble technique" to aid in success in anwar's "big bubble technique" of deep lamellar keratoplasty with complete baring of descemet's membrane

Microbubble incision as a new rescue technique for big-bubble deep anterior lamellar keratoplasty with failed bubble formation

PURPOSE

To describe a new surgical technique allowing dissection down to Descemet membrane in big-bubble deep anterior lamellar keratoplasty (DALK) with failed big-bubble formation (the "microbubble incision technique").

METHODS

This is an interventional case series of 10 consecutive patients with keratoconus undergoing intended big-bubble DALK with failure to establish a normal big bubble. In all patients, repeated air injections into the stroma were performed, leaving a whitish colored stroma. Lamellar dissection as far down as possible was then performed within this white tissue. As soon as the anterior chamber was visible, a large remaining intrastromal air bubble was incised with a sharp 15-degree knife introduced perpendicular to the tissue to open up this predescemetic bubble. If deeper air bubbles were still visible, this approach was repeated. Using a blunt spatula, this new layer was then prepared and viscodissection performed.

RESULTS

Using this novel approach, in 9 of the 10 patients, it was possible to dissect down to Descemet membrane. Macroperforation made conversion to penetrating keratoplasty necessary in 1 patient. Microperforations not necessitating conversion occurred in 2 patients. All 9 patients with "rescued" DALK had an uneventful postoperative course and had a mean visual acuity of 20/63 ± 20/125 (range, 20/500-20/50) and a mean endothelial cell count of 1672 ± 163 cells per square millimeter (range, 1493-1867 cells/mm) at 3 months.

CONCLUSIONS

Microbubble incision is a new rescue technique for big-bubble DALK patients without bubble formation allowing for a safer dissection down to Descemet membrane.

Intraoperative perforation of Descemet's membrane during "big bubble" deep anterior lamellar keratoplasty

To analyze the reasons for intraoperative perforation of Descemet's membrane during deep anterior lamellar keratoplasty (DALK) during the learning curve. DALK was attempted in 35 eyes of 33 patients with pathologies involving the corneal stroma and sparing of Descemet's membrane (DM), including patients with keratoconus, corneal stromal dystrophies and healed keratitis. The surgical plan included complete removal of the corneal stroma using the "big bubble" technique for exposing Descemet's membrane followed by grafting of a full-thickness corneal stromal lenticule. DALK was converted into full-thickness penetrating keratoplasty in eight eyes (23%), which included patients with keratoconus (n = 6), macular corneal dystrophy (n = 1) and healed keratitis (n = 1). Main reasons for conversion were perforation of the DM due to excessive air injection (four eyes) and improper surgical maneuvers (three eyes). One case had deposits on Descemet's membrane upon exposure of the DM. A successful penetrating keratoplasty could be performed in all eight eyes. During the learning curve, excessive air injection and inappropriate surgical maneuvers may complicate a DALK resulting in conversion to penetrating keratoplasty.

Anterior lamellar keratoplasty: 'Back to the Future'- a review

Newer forms of lamellar keratoplasty techniques have emerged in the last decade or so revolving around the concept of targeted replacement of diseased corneal layers. These include anterior lamellar keratoplasty (ALK) techniques that aim to selectively replace diseased corneal stroma and, endothelial keratoplasty techniques aiming to replaced damaged endothelium in endothelial disorders. ALK surgery has a distinct advantage over penetrating keratoplasty (PK) in that it minimizes unnecessary replacement of the unaffected healthy endothelial layer thereby almost eliminating the risk of endothelial rejection, a major cause of graft failure in PK. Overall it provides increased life expectancy to the graft and with advancements in the surgical technique and instrumentation for ALK, the visual outcomes are now comparable if not better to standard PK. There are several forms of ALK procedures that have evolved to cater to a wide range of stromal disorders. This article reviews the various emerging techniques of anterior lamellar surgery, its indications and visual outcomes, to emphasize the shift from PK to ALK for stromal disorders with a healthy endothelium.