Deep Anterior lamellar Keratoplasty: In search of Holy Grail!

Deep Anterior lamellar Keratoplasty (DALK) has become the corneal transplantation technique of choice for corneal diseases that spare the corneal endothelium. The major indications include keratoconus, stromal corneal dystrophies, corneal scars that spare the Descemet membrane (DM) and recalcitrant infectious keratitis. Unlike the old technique of penetrating/full thickness corneal transplantation, DALK is bereft of dreaded life time risks of endothelial rejection, Endothelial failure, secondary glaucoma etc and besides achieving excellent visual outcomes, DALK has all the advantages of a lamellar procedure: avoiding most complications associated with “open-sky” surgery of full thickness corneal transplantation. Gasset was the first to publish successful results of his DALK Technique in patients of keratoconus. Most of the patients (80%) in his series achieved a visual acuity of 20/30. The goal ofDALK is to achieve a depth of dissection as close as possible to DM and various modalities have been used to create a plane of separation between DM and the deep stromal layers. These include manual dissection, air-assisted dissection, hydrodelamination, viscoelastic-assisted dissection, and femtosecond laser. Ophthalmic literature is full of various DALK techniques and their modifications, each claiming to be optimal, safe and more effective. All these techniques can be broadly classified in two major categories; predescematic DALK and descematic DALK. While melles technique is the most popular predescematic technique of DALK, Descematic DALK is usually performed using Big Bubbble Technique in which air is injected in cornea to bare and separate healthy DM from rest of the diseased cornea. While both techniques deliver excellent visual outcomes, they are somewhat difficult to practice in cases of advanced keratoconus and very thin corneas. Also, each of these two techniques carry some inherent disadvantages that can preclude achievement of optimal results in a consistent manner. In big bubble technique, many times big bubble would not form and injection of air makes cornea emphysematous and opaque. Moreover, if DM perforates, a