Descemet membrane endothelial keratoplasty (DMEK) is a method of

corneal transplantation Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft). When the entire cornea is replaced it is known as penetrating keratoplasty a ...

that involves the removal of a thin sheet of tissue from the posterior (innermost) side of a person's cornea to replace it with the two posterior (innermost) layers of corneal tissue from a donor's eyeball. The two exchanged corneal layers are the

Descemet's membrane Descemet's membrane ( or the Descemet membrane) is the basement membrane that lies between the corneal proper substance, also called stroma, and the endothelial layer of the cornea. It is composed of different kinds of collagen (Type IV and VIII ...

and the

corneal endothelium The corneal endothelium is a single layer of endothelial cells on the inner surface of the cornea. It faces the chamber formed between the cornea and the iris. The corneal endothelium are specialized, flattened, mitochondria-rich cells that ...

. The person's corneal tissue is gently excised, peeled off, and replaced with the donor tissue via small 'clear corneal incisions' (small corneal incisions just anterior to the

corneal limbus The corneal limbus (''Latin'': corneal border) is a highly vascularized and pigmented zone between the cornea, conjunctiva, and the sclera (the white of the eye) that protects and heals the cornea. The cornea is composed of three primary cell ty ...

. The donor tissue is

tamponade Tamponade () is the closure or blockage (as of a wound or body cavity) by or as if by a tampon, especially to stop bleeding. Tamponade is a useful method of stopping a hemorrhage. This can be achieved by applying an absorbent dressing directl ...

d against the person's exposed posterior corneal stroma by injecting a small air bubble into the

anterior chamber The anterior chamber ( AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Hyphema, anterior uveitis and glaucoma are three main pathologies in this area. In hyphema, ...

. To ensure the air tamponade is effective, people must maintain such a posture that they look up at the ceiling during recovery until the air bubble has fully resorbed.

Medical uses

Indications for DMEK include: *

Corneal dystrophy Corneal dystrophy is a group of rare hereditary disorders characterised by bilateral abnormal deposition of substances in the transparent front part of the eye called the cornea. Signs and symptoms Corneal dystrophy may not significantly affect ...

involving the corneal endothelial layer, e.g.: **

Fuchs' endothelial dystrophy Fuchs dystrophy, also referred to as Fuchs endothelial corneal dystrophy (FECD) and Fuchs endothelial dystrophy (FED), is a slowly progressing corneal dystrophy that usually affects both eyes and is slightly more common in women than in men. Althou ...

Posterior polymorphous corneal dystrophy Posterior polymorphous corneal dystrophy (PPCD; sometimes also ''Schlichting dystrophy'') is a type of corneal dystrophy, characterised by changes in Descemet's membrane and endothelial layer. Symptoms mainly consist of decreased vision due to c ...

* Pseudophakic bullous keratopathy * Iridocorneal endothelial syndrome

Nomenclature

A minor variation to DMEK is the Descemet Membrane Automated Endothelial Keratoplasty (DMAEK), which involves automated donor tissue preparation using a microkeratome or

femtosecond laser Mode locking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds (10−12 s) or femtoseconds (10−15 s). A laser operated in this way is sometimes r ...

References

{{Eye procedures Eye procedures Corneal transplantation Medical procedures Eye surgery Ophthalmology

Medical uses

Nomenclature

See also

References