History of the development of selective keratoplasty and its possibilities

Relevance In 1914, A. Elschnig successfully performed penetrating keratoplasty (PKP) with an allograft, which is now recognized as a standard treatment for corneal opacity along with its modifications. Modern technologies allow the creation of thin transplants of donor material [1, 2], which is the basis of the selective keratoplasty method. This approach allows the surgeon to replace only the affected layers of the cornea, while preserving healthy tissue, which increases the effectiveness of surgical intervention and minimizes complications. Currently, there are two main types of selective keratoplasty: anterior lamellar and endothelial. The review examines the key stages in the formation of modern approaches to performing these modifications. In 1959, W. Hallermann described manual anterior lamellar keratoplasty with a corneal disc without endothelium. Analysis showed that contact of the endothelial layer of the transplant with the cornea disrupts adaptation and causes local fibrosis. Later, E. Malbran proposed replacing the removed layers of the cornea with a transplant of the desired thickness and structure. In 1974, M. Anwar proposed deep anterior lamellar keratoplasty (DALC), including trepanation of the stroma to 2/3 of the depth and detachment to the Descemet membrane (DM) [3]. The smooth surface of the DM promotes adhesion of the layered transplant and prevents scarring. In Russia, M.M. Krasnov developed a modification of DALC - complete stromoplasty. One of the stages of DALC development includes a method of detachment of the DM by intrastromal administration of a balanced saline solution or viscoelastic drug, but this often requires manual dissection, which increases the risk of damage. In 1984, E.A. Archila proposed to inject air into the stroma to define the depth of the DM and reduce the risk of perforation. The big bubble technique described by Anwar and Teichmann in 2002 uses air injection via a cannula to create a bubble, which has become the most popular modification of the GPPC. In 2013, H.S. Dua proposed three types of DM detachment using the big bubble technique, including bleb formation in the central or peripheral zones. Endothelial keratoplasty replaces the damaged corneal endothelium with a graft from the posterior layers of donor tissue. The first operation of this type was performed in 1956 by C.W. Tillet, using a corneoscleral approach and fixing the posterior layered graft with mattress sutures. Since then, new techniques have been developed, for example, in 2004, G.R. Melles proposed descemetorhexis, which allows achieving a flat surface of the recipient stroma and improving contact with the graft. Modern techniques include DSAEK and DMEK. DSAEK performed with a microkeratome is a stand-alone technique and allows for a graft thickness of up to 170 μm. DMEK, developed by Melles in 2006, involves replacing the endothelium and DM with healthy donor layers. These surgeries do not require sutures, but an air bubble or gas mixture is introduced to fix the grafts [4]. Conclusion Modern methods of visualizing the anterior segment of the eye and the development of microsurgery have made it possible to introduce the principle of selective replacement of diseased corneal layers with donor tissue. Compared with penetrating keratoplasty, procedures such as endothelial keratoplasty and deep anterior lamellar keratoplasty offer a shorter recovery period and a lower complication rate. Keywords: selective keratoplasty; deep anterior lamellar keratoplasty; Descemet's membrane; endothelial keratoplasty