Choose the content to read

• Why DMEK?
• What diseases does DMEK treat?
• What is the DMEK surgery procedure?
• What is the difference between DMEK and DSAEK?
• What is the advantage of DMEK?
• DMEK Corneal Surgery at MedPark Hospital

DMEK Corneal Transplant

DMEK (Descemet membrane endothelial keratoplasty) is a partial-thickness corneal transplant procedure involving removing only the innermost damaged or diseased endothelial corneal layers and replacing them with healthy donor endothelial corneas without the need for a full-thickness corneal transplant. DMEK corneal transplant is appropriate for those with eye abnormalities or diseases in only the posterior cornea (layers 4-5) but a healthy anterior cornea (layers 1-3). The ophthalmologist inserts a thin layer of corresponding healthy donor corneal tissue through a small incision; the anterior and posterior cornea layers will be firmly adhered to and layered together with the utilization of the air bubble pressure. The new posterior cornea layers will gradually suction out water from the cloudy cornea, allowing the cornea a clear visualization. DMEK uses a flapless technique without stitching, reducing infection-related complications and accelerating a speedy recovery.

Why DMEK?

Previously, ophthalmologists treated Fuchs' endothelial corneal dystrophy, bullous keratoplasty, corneal edema from iridocorneal endothelial syndrome, or endothelial cell (layer 5) abnormalities with full-thickness cornea transplant (penetrating keratoplasty: PKP). This procedure affected the strength and curvature of the cornea and increased the risk of graft rejection, changes in nearsightedness, farsightedness, astigmatism, a slow healing process, and a high rate of infection-related surgical suturing.

DMEK is advanced cornea transplantation that involves the selective removal of only the innermost posterior cornea layers and transplantation of a healthy donor cornea with only 10 microns thick—4 times thinner than a sheet of paper—which helps preserve the anterior cornea in good condition, leaves a tiny surgical incision size of only 2-3 mm. with only 1 incision without surgical sutures, maintains the strength and natural curvature of the cornea, lowers the risk of infection complications, promotes quick recovery, and improves visual acuity comparable to normal vision.

What diseases does DMEK treat?

DMEK treats the inner corneal epithelium, including Descemet's membrane and endothelium, that has degenerated due to the diseases or abnormalities listed below.

• Fuchs’ endothelial corneal dystrophy
• Posterior polymorphous membrane dystrophy
• Bullous keratoplasty
• Iridocorneal endothelial syndrome (ICE)
• Congenital hereditary endothelial dystrophy
• Previous corneal graft rejection

What are the symptoms of corneal dystrophies?

• Blurred vision, difficulty seeing clearly.
• Eye discomfort, eye pain
• Eye light sensitivity
• Decreased night vision or reduced contrast sensitivity
• Eye irritation, feeling like something in the eye (Blepharitis)
• Glare, difficulty driving at night
• Fluctuation in vision, typically worse in the morning and improving toward the end of the day

What is the diagnosis before DMEK?

The ophthalmologist will perform the following assessment before determining if the patient is a qualified candidate for DMEK, Descemet membrane endothelial keratoplasty, including obtaining a medical history, performing a thorough eye examination with a slit lamp biomicroscope, and performing additional evaluations, including specular microscopy, pachymetry, and anterior segment optical coherence tomography.

What is the DMEK surgery procedure?

Preoperative DMEK surgery procedures

• Once the ophthalmologist determines that a patient is a qualified candidate for DMEK corneal transplant surgery, the hospital will then place the patient on a waiting list to receive corneal donations from the local eye bank. In urgent cases, the hospital will determine imported donor corneal tissue from aboard.
• Once a donor cornea from the eye bank is confirmed, sterilized, and healthy, the hospital will inform the patient and schedule the surgery date.
• The ophthalmologist will schedule pre-corneal transplantation to undergo a laser peripheral iridotomy to reduce the risk of postoperative intraocular pressure elevation.
• The hospital will schedule a physical examination before the surgery date, as follows:
  
  • Blood Tests
  • Chest X-ray
  • Electrocardiogram (EKG/ECG)

Intraoperative DMEK surgery procedures

• The ophthalmologist performs DMEK corneal replacement surgery by making a 2-3 mm tiny single incision on the side of the cornea and carefully peeling off the two posterior deteriorated cornea layers (layers 4-5), leaving the healthy anterior cornea layers (layers 1-3) intact and undisturbed.
• The ophthalmologist will then conduct DMEK corneal transplant surgery by gently inserting the healthy donor cornea layers 4 (Descemet's membrane) and 5 (Endothelial cell) through the same incision to replace the deteriorated cornea, using air bubble pressure to push the two innermost transplanted posterior cornea layers against the anterior cornea layers.
• All corneal layers will naturally adhere, layer together, and suture themselves without the need for stitches. The new posterior cornea layers will slowly suck out water off the cloudy eye, which results in gradually resolved corneal swelling and improved vision. DMEK surgery procedure typically takes 1 hour, depending on the complexity of the patient and any concurrent operations like cataract surgery.

Postoperative DMEK surgery procedures

• The ophthalmologist will cover the eyes with eye gauze and an eye shield.
• The ophthalmologists and nurses will closely monitor the symptoms for the first hour after surgery.
• The patients will be instructed to lay flat on their backs for the first hour of recovery to allow air bubbles to float to the front of the eye and press the graft against the back of the cornea, facilitating its adhesion to the posterior cornea.
• The patient is allowed to go to the restroom, sit, stand, walk, drink, and eat as usual.
• The ophthalmologist evaluates symptoms after treatment; if no complications are found, they can return home.

What is postoperative care for DMEK?

• The ophthalmologist will schedule a follow-up appointment the day after the surgery.
• The patient must lie on their back for 3–4 days to 1 week, depending on the amount of residual air inside the eye.
• The ophthalmologist will schedule a re-injection of the air bubbles 2-3 days after surgery.
• For 1 week, cover the eye shield during the day and at night to prevent the eye from being rubbed.
• Always instill eye drops on time, as directed by the ophthalmologist to prevent infection.
• Avoid watching screens or spending too much time on screen; instead, take breaks periodically.
• For 1 week, refrain from washing your face, rubbing your eyes, or squeezing your eyes.
• For 1 week, refrain from sweat-inducing activities or exercises that may enter your eyes.
• Light exercise, such as walking, is permitted during the first postoperative week.
• Refrain from jogging or strenuous exercise for 3 to 4 weeks.
• Attending all ophthalmologist appointments at the hospital to monitor symptoms and evaluate treatment outcomes.

What is the recovery time for DMEK?

DMEK corneal transplant surgery requires 2-3 weeks for recovery. Typically, vision will gradually improve within 1-3 months, depending on the individual’s physical condition, unlike the traditional full-thickness cornea transplant procedure, which takes months or years for full visual rehabilitation.

What is the difference between DMEK and DSAEK?

DMEK and DSAEK are partial-thickness cornea transplant procedures using the corneal layer 4-5. Cornea layer 4 is Descemet's membrane, and layer 5 is endothelial. The difference between DMEK and DSAEK is that the DSAEK cornea transplant procedure includes the use of stromal tissue (part of layer 3), whereas DMEK only uses the 4 and 5 cornea layers.

What is the advantage of DMEK?

• Tiny incision: DMEK has only a tiny surgical incision of only 2-3 mm. on the side of the cornea, which aids in wound healing and recovery.
• No stitches required: DMEK is a stitch-free surgical technique. After the surgery, air bubble pressure presses the transplanted layer against the native cornea, lessening suture-related complications, including infection and surgically induced corneal astigmatism.
• Fast recovery: DMEK employs a minimally invasive surgery (MIS) technique, resulting in less pain and a quick recovery.
• Low risk of graft rejection: DMEK transplants only the two innermost posterior corneal layers without the need to proceed with penetrating keratoplasty (PKP), lowering the risk of graft rejection.
• Low complications: DMEK uses a flapless surgical technique without requiring full eye-opening, reducing serious complications, such as suprachoroidal hemorrhage and infection.
• Preserve corneal curvature: DMEK leaves the anterior cornea structurally intact, which allows for resilient corneal integrity and preserves the cornea’s natural curvature to the greatest extent.
• Treats disease promptly: DMEK removes deteriorated or diseased cornea while preserving the remaining healthy corneal layers. The new cornea will gradually suck water out of the cloudy cornea, allowing the entire cornea to become clear and restore vision.
• Accelerate clear vision: Compared to other corneal transplant surgeries, which take months or years to produce clear vision, DMEK surgical technique shortens the recovery time, achieving clear vision within 1-3 months.

What is the disadvantage of DMEK?

• Graft dislocation or detachment: Graft dislocation from its position may occur after DMEK. In this case, the ophthalmologist will reposition the graft under tropical anesthesia, with 15-minute operations, using an air or gas bubble injection into the anterior eye chamber.
• Graft rejection: Although DMEK endothelial keratoplasty has the lowest risk of immune rejection compared to DSAEK or a full-thickness corneal transplant, the immune system still could reject the corneal graft. Therefore, the follow-up appointment is crucial for early detection of graft failure.
• Infection: Post-operative ocular infection is a potential complication following any eye surgery, which can lead to unfavorable outcomes. However, the likelihood of infection in patients undergoing DMEK is very low due to a tiny incision and flapless technique, making the infection rate less than 1 in 1000 cases.

What is the success rate of DMEK?

According to the study's findings, individuals who undergo DMEK corneal transplant surgery have a nearly 90% success rate at 5 years. The patients can achieve corrected 20/20 visual acuity within 1 year of the surgery. The best achievable visual outcomes are faster than other corneal transplant procedures.

DMEK Corneal Surgery at MedPark Hospital

Eye Center at MedPark Hospital, Bangkok, Thailand is led by a team of specialized ophthalmologists with national acclaim and international experience who are ready to diagnose and treat both common ophthalmologic conditions and complex corneal dystrophies with corneal transplant surgery, including partial-thickness cornea transplant: DMEK, DSAEK, and DALK and full-thickness cornea transplant: PKP to restore vision and improve quality of life using state-of-the-art medical technology and equipment and the highest standard of care, aiding in treatment safety, speed up recovery, and maximizing treatment efficiency, while also providing post-treatment follow-up to prevent complications, accelerate vision recovery, and allow patients to have a long-lasting healthy eyes as possible.