Descemet’s stripping endothelial keratoplasty (DSEK) is a surgical procedure where the surgeon uses donor Descemet membrane (DM) and endothelium tissue to replace the diseased host DM and endothelium. The surgeon transplants a tiny amount of posterior stromal thickness through a corneoscleral incision. Descemet stripping automated endothelial keratoplasty (DSAEK) is a form of DSEK, the only difference being the addition of a microkeratome.
DSEK is a kind of endothelial keratoplasty (EK) where the surgeon selectively removes a patient’s DM and transplants donor corneal stroma and endothelium. Healing and visual rehabilitation are quicker in DSEK, and the risk of graft rejection is lower. Besides, suture-related complications are fewer than in PK and DALK. The corneal curvature topographic changes also remain at a minimum.
DSEK may be used to treat the following conditions:
- Glaucoma drainage services
- Fuchs’ endothelial dystrophy
- Iridocorneal endothelial (ICE) syndrome
- Posterior polymorphous corneal dystrophy
- Congenital hereditary endothelial dystrophy
- Endothelial failure following a previous PK graft
- Aphakic and pseudophakic bullous keratopathy
- Decreased vision from corneal swelling due to a poorly functioning endothelium, such as after cataract or another eye surgery
However, patients with visual limiting stromal scarring or opacity are not suitable candidates for DSEK/DSAEK. Patients with anterior dystrophies, hypotonic eyes, and corneal ectasia (keratoglobus, keratoconus, pellucid marginal degeneration, etc) should also not undergo the procedure. These diseases do not affect the corneal endothelium.
Before the Procedure
Before the surgery, the tissue is prepared following the laid down procedure. The donor should be aged two to 75 years with donor tissue preserved for a maximum of seven days. There are specifications as to the thickness or thinness, diameter, and density of donor tissue. The surgeon may prepare the tissue just before the procedure or have an eye bank prepare it. The appropriate depth of the microkeratome blade is decided upon based on pachymetry measurements. The tissue is stored in an artificial anterior chamber, and a microkeratome used to slice the anterior cornea while maintaining the DM, a thin layer of the stromal posterior, and endothelium.
The patient will have their medical history taken and eye tests conducted. In the eye tests, the doctor takes measurements, including corneal thickness, pupil dilation, and refractive error. Patient education and counselling are equally important because the patient needs to understand the risks and benefits and have realistic expectations.
The patient is administered with local or general anesthesia. During the procedure, the surgeon:
- Uses a particular type of blade to make one to three paracentesis incisions
- Uses a cohesive viscoelastic to fill the anterior chamber
- Creates a temporal, superior, or along the axis of astigmatism anterior chamber incision
- Using a Price hook or reverse Sinskey, scores and strips the DM and endothelium
- Uses special insertion instruments to insert the donor tissue
- Closes the incision using a nylon suture
- Injects air or balanced salt solution to unfold the tissue completely
- Injects an air bubble beneath the tissue to form apposition between the host and donor corneal stroma
- Reduces the risk of a pupillary block by placing a peripheral iridectomy
- Administers corticosteroid injections and subconjunctival antibiotics
Risks & Complications
DSEK/DSAEK presents fewer risks and complications if the surgeon has increased surgical experience. Risks and complications may manifest in the graft preparation stage. The tissue may get perforated, or a lenticule with an irregular surface may arise. DSAEK may cause endothelial damage, perforated tissue, and a decentered cut during tissue preparation.
Intraoperative complications may include endothelial trauma, cataract development, graft tissue expulsion, and inability to maintain a full air fill.
Postoperative risks and complications may include:
- Secondary graft failure
- Cystoid macular edema
- Air bubble-related pupillary block
- Epithelial ingrowth or interface haze
- Suprachoroidal haemorrhage (though rare)
- Secondary glaucoma often induced by steroids
- Though rare, infectious complications like interface keratitis and endophthalmitis
- Primary graft failure which can be caused by iatrogenic trauma necessitating a repeat procedure or PK with new donor tissue
- Graft rejection though it is less frequent with DSEK than with PK. It may be treated with frequent topical steroid instillation or a repeat procedure
- Graft dislocation which often occurs in the early days following surgery. If wholly detached, the surgeon may inject in the air to reposition the graft
Aftercare & Recovery
Immediately after surgery, the patient lies in a supine position for at least 24 hours so that the air bubble is continuously in opposition with the host and donor stroma. The surgeon releases the air bubble to a 60-70% anterior chamber fill one hour after the procedure. The surgeon also places a protective shield over the operated eye. Topical antibiotics and steroids are administered three times on the day of the procedure or the following day. The antibiotics are used for ten days while cycloplegics will be used for one to two days or for as long as the bubble is present.
The first follow up visit occurs the day after surgery, then in the first week. The patient will be seen after one month, then three months. However, some surgeons opt to closely follow up the patient in the first week to check on the air bubble and if a graft detachment has occurred.
Patients who undergo DSEK/DSAEK recover faster than PK patients. Recovery usually occurs in a matter of weeks. Patients can achieve the best spectacle-corrected visual acuity of 20/20 in about one year. Besides, DSEK/DSAEK induces low levels of topographic changes; hence, less irregular astigmatism than PK.