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 afffecting only the posterior cornea (layers 4-5) but a healthy anterior cornea (layers 1-3). The thin layer of healthy donor corneal tissue is inserted through a small incision; the graft is supported by an air bubble and adhered to the anterior cornea layer without the need for sutures. As the corneal tissue cells gradually fuse, the new endothelial cells slowly pump water out of the cloudy cornea, allowing the cornea to become clear, reducing swelling, and restoring clear vision.
Why DMEK?
Previously, ophthalmologists treated Fuchs' endothelial corneal dystrophy, bullous keratoplasty, 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, increased the risk of graft rejection, changed corneal astigmatism, slowed the healing process, and caused complications from sutures.
DMEK is an advanced cornea transplantation that involves the selective removal of only the innermost posterior cornea layers and transplantation of a healthy donor cornea, which is only 10 microns thick—4 times thinner than a sheet of paper—which helps preserve the anterior cornea in good condition and leaves a very small surgical incision size of only 3 mm. This procedure eliminates the need for suturing the corneal graft to the recipient, preserves the cornea's strength and natural curvature, lowers the risk of infections, expedites the healing process, and improves visual acuity comparable to normal vision.
What diseases can be treated by DMEK?
DMEK can be used to treat diseases or abnormalities that cause corneal swelling by affecting the innermost layer of the cornea, including Descemet's membrane and the endothelium, as follows:
- Fuchs’ endothelial corneal dystrophy
- Posterior polymorphous membrane dystrophy
- Bullous keratoplasty
- Iridocorneal endothelial syndrome (ICE)
- Congenital hereditary endothelial dystrophy
- Failed previous corneal transplant
What are the symptoms of corneal endothelial dysfunction?
- Blurred vision, difficulty seeing clearly.
- Fluctuation in vision, typically worse in the morning and improving toward the end of the day
- Dim-brightness vision or reduced contrast sensitivity
- Light sensitivity
- Glare, or have difficulty with nighttime driving
- Eye discomfort, eye pain
- Recurrent foreign body sensation
What is the diagnosis before DMEK?
The ophthalmologist will perform the following assessments before determining if the patient is a qualified candidate for DMEK, Descemet membrane endothelial keratoplasty, including obtaining a medical history, performing a comprehensive eye examination using a slit lamp biomicroscope, and conducting 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 abroard.
- Once a donor cornea from the eye bank is confirmed, sterilized, and healthy, the hospital will notify the patient and schedule the surgery date.
- Prior to the scheduled surgery date, the ophthalmologist may arrange for 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 creating a 3 mm incision on the side of the cornea and carefully peeling off the two posterior compromised or diseased cornea layers (layers 4-5), leaving the healthy anterior cornea layers (layers 1-3) intact and undisturbed.
- The ophthalmologist will then gently insert the healthy donor cornea layers 4 (Descemet's membrane) and 5 (Endothelial cells) 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, eliminating the need for sutures.
- The new posterior cornea layers will slowly suck out water from the cloudy eye, which results in gradually decreased corneal swelling and improved vision. Typically, a DMEK corneal transplant takes approximately 1 hour, depending on the complexity of the patient and any concurrent operations such as 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 lie flat on their backs and rest for the first hour in the recovery room 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, the patient 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.
- In some cases, the ophthalmologist may 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 and control inflammation.
- Avoid excessive screen time or screen-based activities on electronic devices; instead, take periodic pauses.
- 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 cause sweat to 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 conditions and coherence factors such as disease, degree, and duration of the cornea's initial swelling, 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 both partial-thickness cornea transplant procedures. The main difference between DMEK and DSAEK is that the DMEK cornea transplant procedure uses only cornea layers 4 and 5 without the use of stromal tissue (part of layer 3). Therefore, DMEK grafts are much thinner, lower the risk of graft rejection, and restore vision faster than DSAEK.
What is the advantage of DMEK?
- Tiny incision: DMEK has only a tiny surgical incision of 3 mm on the side of the cornea, which accelerates wound healing and recovery.
- No corneal-graft sutures: After DMEK surgery, the corneal graft is attached by intraocular pressure and bubble pressure from air or gas without the need for sutures, lessening suture-related complications, including infection and surgically induced corneal astigmatism.
- Fast visual recovery and stability: The graft used in DMEK surgery is very thin, and the surgery leaves the anterior corneal surface intact, resulting in faster healing, less pain, a minimal change in induced corneal astigmatism, and an optimal visual outcome.
- Less risk of corneal graft rejection: DMEK transplants only the two innermost posterior corneal layers, reducing the proximity of the grafted tissue to blood vessels on the corneal surface and lowering the risk of graft rejection.
- Less risk of sight-threatening complications: DMEK can be performed through relatively small incisions and does not require the eye to be completely opened, reducing serious complications, such as suprachoroidal hemorrhage and infection.
- Stronger wound integrity: DMEK leaves the anterior cornea structurally intact, allowing for strong wound integrity and making it less susceptible to injury.
- Accelerate clear vision: Compared to other corneal transplant surgeries, which take months or years to yield clear vision, the DMEK surgical technique shortens the recovery time, achieving clear vision within 1-3 months.
What is the disadvantage of DMEK?
- Graft dislocation or detachment: In patients undergone DMEK, graft dislocation from its position may occur. In this case, the ophthalmologist will reposition the graft under topical anesthesia, using an air or gas bubble injection into the anterior eye chamber.
- Graft rejection: Although DMEK has the lowest risk of immune rejection compared to DSAEK or a full-thickness corneal transplant, the corneal graft may still be rejected by the body's immune system. 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 capable of diagnosing and managing both common ophthalmologic conditions and complex corneal diseases 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, speeding up recovery, maximizing treatment efficiency, and allowing patients to have as healthy, long-lasting eyes as possible.
