Both the DMEK such as DSAEK are surgical techniques that we use to perform a transplant of cornea selective posterior, in which the endothelium-Descemet unit is replaced and whose purpose is to treat tissue alterations endothelial. However, despite their similarity, they have different characteristics.
En Área Oftalmológica Avanzada we explain if there is a better technique than the other and what differences exist between the DMEK or the DSAEK.
Differences between DMEK and DSAEK
DMEK and DSAEK are two surgical techniques to perform a type of cornea transplant known as posterior lamellar keratoplasty o endothelial keratoplasty, that is, interventions to treat alterations of the corneal endothelium.
Both offer a very fast visual rehabilitation with a minimum refractive change, in addition to a greater integrity of the cornea. Additionally, they avoid some of the complications that are often caused by penetrating keratoplasties.
In the case of the DSAEK a lenticule of 80-100 microns, of posterior stroma next to Descemet's membrane and its endothelium. Said lenticule is obtained by making a cut on the donor cornea with a specific microkeratome for this procedure. On the other hand, in the DMEK only the Descemet's membrane with its endothelium, without stromal support and is obtained by manual dissection.
Another important difference between DMEK and DSAEK is the way we obtain the tissue to transplant. In the case of DMEK, It is more artisanal and complex and depends largely on the skill of the surgeon since it is done by hand, While in the DSAEK, a much more automated and reliable dissection system.
Advantages and disadvantages of DMEK and DSAEK
Most corneal pathologies occur specifically in one of the layers of the cornea, so the selective replacement of corneal layers damaged, it is much more advantageous than when transplanting the full thickness of the cornea (penetrating transplant).
The results published with DMEK show some advantages over DSAEK, especially related to better visual quality what would this surgery offer.
Our main advantages of DMEK against the DSAEK are the following:
- Visual results of DMEK are better in relation to the following aspects:
- DMEK only replaces the tissue that has been removed from the patient, Descemet's membrane and the diseased endothelium, contrary to what happens in DSAEK, in which case part of the donor stroma is also implanted, which has a different refractive index .
- Optical aberrations. DMEK shows a significantly lower level of higher order aberration than eyes after DSAEK.
- Hypermetropization. The DSAEK can produce a hypermetropia of 1 to 3 diopters. In contrast, DMEK only produces small transient changes, since the swollen cornea has a higher than normal refractive index.
- Recovery. Patients usually achieve vision that can reach 100% a few weeks after DMEK. Average vision after DSAEK is 65% to 90%, and although it tends to improve over time, in many cases it does not recover 100% as in DMEK.
- DMEK reduces the chances of rejection implanted tissue. Any corneal transplant procedure can lead to graft rejection. However, it has been found that in the case of DMEK there is less chance that the donor tissue will be rejected.
- The loss of endothelial cells, another possible consequence of these interventions, also is minor in DMEK than in DSAEK.
- To perform a DMEK no special technology is required, like the microkeratome, in the case of DSAEK.
The main disadvantage of DMEK versus DSAEK is complexity of surgery, the frequency of re-intervention as well as the endothelial cell loss during the surgical procedure. Even with highly skilled surgeons, the dissection of the endothelium from the donor cornea can be complicated, damaging the endothelial cells and reducing the chance of their survival, causing surgery to fail or the final vision not as good. In this surgical option there are also more cases in which the graft does not adhere well and it is necessary to return to the operating room to reposition it, with the inconveniences that this entails for the patient and the possible deterioration of the endothelium when having to manipulate it again.
La main advantage of DSAEK is that it is a technique not so complex and easier to manipulate the implanted lenticule. It is not necessary to carry out the manual dissection, we use a microkeratome similar to the ones we use in refractive surgery and that we are already used to handling it. On the other hand, the lenticule that we implant is somewhat more consistent and its handling, implantation and placement is easier, which allows there to be no loss of endothelial cells due to excessive handling.
Once the implant has been placed inside the eye and its good location and adherence to the recipient stroma confirmed, less likely to separate and that it is necessary to relocate it, as in the case of DSAEK.
La The main disadvantage of DSAEK compared to DMEK is the quality of vision obtained. It is true that if both surgeries are performed correctly and there are no complications, the quality of vision obtained with DMEK is superior, being able to reach 100% in most cases. En el DSAEK, 60-80% recovery is obtained of vision in the first weeks and in some cases, can improve up to 90-100% after a few months or even 1 year.
They are not very important differences between the two techniques, but it is necessary to consider them depending on the type of patient. In cases where it is young patients who have to drive or require a high level of vision, we prefer to raise a DMEK. In cases where the visual demand is not so important, we prefer to indicate a DSAEK, due to its greater reliability and lower degree of complications.
When to perform a DSAEK or DMEK?
We have already seen the advantages and disadvantages of each. Both techniques show good results and represent a very important advance over the classic penetrating transplant, especially when the lesions of the cornea do not affect all its layers.
The dilemma is between the better visual quality of DMEK versus the greater safety of surgery in DSAEK. These two circumstances must be weighed in each patient and in their personal situation. In cases where it is young patients who have to drive or require a high level of vision, we prefer to raise a DMEK. On cases where visual demand is not so important, we prefer to indicate a DSAEK, due to its greater reliability and lower degree of complications.
Do you have more questions about differences between DMEK and DSAEK? En Área Oftalmológica Avanzada we are experts in these two interventions. If you wish, you just have to contact us, we will be delighted to help you!