DISCLAIMER! The information on this website is general information. Please discuss with your surgical provider your concerns and questions about the procedure. Your personal health information may differ from the information presented here.

DMEK (Descemt Membrane Endothelial Keratoplasty) Cornea Transplant

Introduction

You have a condition that has affected your cornea (the front part  of your eye). Your doctor has determined that you need a corneal transplant. This involves having surgery to replace your cornea with a cornea that has been removed from someone  who has  died. The cornea you will receive is referred to as the donor cornea. The donor cornea to be used for your transplant will be provided by an Eye Bank.

This technique is a modification of the split thickness forms of corneal transplantation  originating  from Deep Lamellar Endothelial  Keratoplasty (DLEK) which we developed and introduced to the United States in the year 2000 and which  we later modified  into Descemet’s Stripping Endothelial Keratoplasty (DSEK). DLEK, DSEK and DMEK are all forms of “endothelial keratoplasty” and are used instead of the full thickness traditional method called “penetrating  keratoplasty” (PK).

First, we want you to know that your condition  can be treated  with any technique  of surgery: PK, DLEK, DSEK or DMEK. Before you decide whether to have DMEK,  please take as much time as you need to ask any questions and to discuss the program with the doctor and the medical staff, or with family, friends or your personal physician.

If you have been advised that DMEK would be a reasonable procedure for your treatment because only one part of your cornea is not working properly. The endothelium layer of your cornea is failing and is causing your cornea to become swollen. The endothelium  is the layer of cells on the inside surface of your cornea. It is this layer that needs to be replaced. Until recently, the only way to replace that layer of cells was with a full thickness corneal transplant.  (PK)

A split thickness transplant of this inner layer is called an “endothelial  keratoplasty”. The DMEK technique would remove (or “strip”) only the diseased  portion of your cornea (like “stripping” wallpaper  off of a wall) and then use a specialized  technique  of preparing  a donor tissue consisting only of  the strip of membrane as a carrier for the membrane carrying healthy pump cells (endothelial cells) which have been affected and diseased in your eye. This technique replaces only the diseased tissue and leaves the rest of your cornea intact.

DMEK, being a modification of DLEK and DSEK, is highly specialized. The benefits it offers over DSEK or DLEK are more rapid visual recovery and higher chance of obtaining  close to the vision potential of the eye. In addition, there appears to be a lower rate of tissue rejection with the DMEK procedure than with DSEK or other forms of corneal transplantation. There are greater challenges in  performing DMEK mostly related to the difficulty of preparing the donor tissue as well as implanting the fragile tissue in the eye. If during the surgery the donor tissue  is damaged, we may consider  proceeding  with surgery using a split thickness graft and thus perform DSEK. If the DMEK donor graft is successfully prepared and transplanted in your eye, we will be watching you closely for dislocation of the graft in the first weeks  after surgery. If at any time, the edges of the graft detach or are loosened or the graft is  fully dislocated, we will return to the clinic minor operating room to reattach the graft using  an air bubble injection. It may require more than one such intervention in the postoperative period to ensure full adhesion of the graft.

The type of transplant procedure that replaces only the diseased endothelial tissue is called an “endothelial keratoplasty” and is a procedure that was developed here in Portland at Devers Eye Institute and has been done under a scientific protocol here at Devers  for over 13 years. The procedure has been performed by Dr. Terry and his team on over 2,000 patients (as of September 2013) with follow-up of up to 13 years. Over 99% of the surgeries have been successful in providing a clear cornea and getting rid of the swelling f the patient’s  cornea.

Split thickness lamellar corneal transplants have been performed for many years to replace the front part of the cornea and have been highly successful. Dr. Terry and his team of corneal surgeons have performed many split thickness  corneal transplants to replace  the front  portion of the cornea over the past 20 years. What is different about this program is that the surgical procedure  involves replacement of the back layers of the cornea rather than the front layers of the cornea. This replacement is done through a small  pocket incision to avoid changes in the front surface of the cornea. By leaving the front surface in the cornea without  sutures or incisions there is an advantage in healing and recovery time for the patient. We have confirmed in our study done from 2000 to today that EK surgery is able to make healing time even faster and more predictable than with standard PK surgery.

Procedures

If you choose to have a DMEK surgery, you will be scheduled on a routine basis that is convenient for you and corresponds to our normal surgical schedule. The surgery will be performed under local anesthesia unless there is a reason for which you would do better with general anesthesia Local anesthesia is when you are “numb” and cannot feel pain, but are awake enough to answer questions. General anesthesia is when you are completely asleep during the procedure.

During the surgery a single 3 .5  mm long line incision is made in the cornea, a pocket is formed, and just the diseased endothelial layer of your cornea will be removed by gently “stripping”  the diseased tissue off, like peeling wallpaper off of a wall. The donor endothelium carried on a membrane called the Descemet’ s membrane of the donor cornea is then placed through the incision and pocket and placed into position on the back surface of your cornea to replace the diseased tissue that was removed. A large gas bubble (20%  SF6 inert gas) is placed to keep the tissue firmly in place until after a few minutes it can adhere on its own. A small opening is made in the iris (the colored part of the eye) to help prevent high pressure buildup in your eye during the first few days after surgery. The initial incision is then closed with one small sutures and the procedure is completed.

The surgical procedure will take about one hour to perform, slightly longer than a standard PK (45 minutes). If you also have a cataract of the lens of the eye, then cataract surgery can be performed at the same time as DMEK surgery. If cataract and DMEK surgery are done, then the surgery takes about 1 and a half hours. You will be required to lie flat on your back, facing the ceiling for one hour immediately after the operation to help the bubble help the tissue to adhere. Surgery is usually done as an outpatient procedure at the hospital and you are sent home with a patch on your eye that same afternoon. We ask that you try to lie flat facing the ceiling as much as possible after you get home for the first night of surgery. You should have minimal discomfort after surgery, and standard over-the-counter pain medications can be taken if necessary. You will return to see your surgeon the next  day. The patch will be removed and your eye will be examined. You will be placed on antibiotic and steroid drops to prevent infection and to help with healing. This first visit after surgery will only take about 15 to 30 minutes, and is primarily done to check the pressure and to be sure that the donor disc is in good position. If the donor disc is detached  or is at risk of detaching, you will be taken back to a clinic minor room for more air bubble to be injected in your eye to help with  reattachment. You will have  a brief visit  to the clinic weekly for two or three visits after surgery, and then again at three months. The visits after 3 months  can be done by your local referring doctor if it is more convenient for you and if your referring doctor agrees with this. Later visits  at 6, 12, and 24 months will require  extra testing of your vision  and of the cornea and will take about 45 minutes to an hour. We would like to do those visits here at Devers Eye Institute, but if it is more convenient for you and  if your referring  doctor  agrees,  those visits also can be done locally by your referring doctor for your convenience. We will of course see you at any time  that you have any concerns, questions  or problems  after your surgery.

The tests that you will have performed at the pre-op visit and after surgery at the 6, 12, and 24 months visits are a vision test, a check for glasses, examination with the standard clinic microscope, a pressure check, and measurements of your cornea with various optical machines which record light reflections from the cornea (corneal maps). None of these tests will be difficult or uncomfortable for you. Once again, if your referring physician is able and willing to perform these tests and send the information to us, then your pre-operative testing and post operative testing can be done locally by your referring doctor for your convenience.

Risks and Discomforts

The following  risks and discomforts of DMEK corneal transplant surgery are the same whether you have a full thickness PK corneal transplant or a split thickness EK corneal transplant. These include:

1. There  is often  mild  discomfort  and “scratchiness”   for one week  after  surgery that may  be treated with Tylenol  or another  drug by mouth.  Immediately  after surgery your eye will be red. There may be temporary  discomfort  to you from the eye examination  or eye drops. This may include stinging, redness or itching.
2. A serious infection  or bleeding occurs in 1  in 1,000  patients.
3. Serious  problems   caused   by  anesthesia   occur   in  1   in   10,000  patients   including   not awakening  from anesthesia or having neurological  problems  from the anesthesia.
4. Developing  high pressure in your eye (glaucoma).
5. Additional   surgery  due  to  healing  problems,  retinal  swelling  or  detachment,   or  loss  of vision.
6. About   20%   of  the  time   after  PK   surgery   the   body’s   immune   system   produces   an inflammation  of the donor cornea.  This  is often  called a “rejection” reaction.  The rejection reaction  is usually  reversible  if treated promptly  but  sometimes  it leads to a failure of the transplant.  Information  to date indicates  that DLEK,  DSEK and DMEK  surgery may have a much  lower  rejection  rate  than  PK  (only  1 % for  DMEK  and  9%  for  DSEK),  but more studies need to be done to determine if this is true.
7. The transplant  may become  cloudy either  because  of rejection,  as described  above,  or for other- reasons.   If this happens  it may be necessary  for you to have another transplant.   The risk of the transplant  failing varies, depending  upon what your current corneal condition  is. Your doctor may be able to provide more precise  information  about your particular  risk.

Risks of split thickness corneal transplant surgery that are unique to split thickness surgery include:

1. Movement  of the lamellar corneal transplant  tissue  (“disc”)  within the eye. If the disc is in good  position  on  the  first  week  after  surgery,  then  it  is  extremely  rare  for  the  disc  to dislodge later. Should the donor tissue disc be found on the first week after DMEK  surgery to be fully dislocated  or partially  detached  at its edges, then it would  require  one or more procedures  to  either  put the tissue  back  into  the proper  position  or rebubble  to help  with adherence  of the  graft.   If the tissue  could  not  be repositioned  we  would  then  perform  a second EK surgery and possibly instead  of DMEK  a different form of EK (i.e.  DSEK).  The documented   dislocation  rate  in  our  hands  for  DSEK  surgery  is  only  2.5%  but  DMEK surgery has a slightly higher chance of dislocations  and failures.  However,  the significantly better vision  and more rapid vision recovery  seen in DMEK  as compared  to DSEK,  as well as a lower rejection  rate is why a patient  would  choose DMEK  rather than DSEK,  despite the slightly higher re-bubble rate.
2. During  surgery,  your  surgeon may find that  it is not possible  to continue  or complete the DMEK  surgery safely.  Because safety of your eye is the highest priority, he/she may decide to stop the DMEK  procedure  and change  the surgery to a standard EK transplant  (DSEK), but this is very rare.
3. The  area over the pupil  where  the donor  tissue  attaches  to your  own cornea  is an area of healing. During  the healing process,  this attachment  area (the “interface”)  has the potential to develop a haze or clouding which  can decrease  your vision from its full potential.  If this happens,  then  a full thickness  transplant  could  be necessary  to restore  the vision.  In our protocol DLEK  series and in our initial DSEK  series, the interface  area is extremely  clear.

Full understanding of the healing of the interface and it’s affect on final vision is still a matter of research. We have found much better interface clarity with DMEK.

1. It is unknown whether  the split thickness  tissue  has a higher risk of becoming  cloudy than full thickness  corneal tissue. Current  information  suggests that the risk is less than standard PK surgery. However, there is the possibility  that the endothelial  cells of the split thickness tissue  could fail and the tissue become  cloudy. This has occurred in only a few of the over
2. 2,000  cases  of DLEK/DSEK   surgeries  we have performed.  In each case, the cloudy donor disc was removed  and replaced  with another donor disc, restoring  the corneal clarity.  There is not enough information  in regards to this matter after DMEK.  If there is ANY problem after your DLEK, DSEK or DMEK  surgery, you always  have the option of a standard  full thickness  PK surgery.
3. General  Anesthesia:  The risks are the same or less as with any other  surgery requiring general anesthesia Serious risk or injury such as neurologic  (brain) damage or death occurs less than  I in 30,000 cases. Your individual  risk can be more thoroughly  discussed with the anesthesiologist prior to the time of surgery. We wish to avoid ANY risk to your general health, and that is why we usually recommend DSEK surgery with local anesthesia

Although we have tried to list all possible risks and discomforts with this DMEK procedure, there may be others that we do not know about at this time.

Benefits

There are possible direct benefits  to you as a patient  receiving DMEK surgery; however, there are no guaranteed  benefits.

1. Patients who have a split thickness corneal transplant such as DLEK/DSEK/DMEK have been shown to have a smoother corneal surface than  patients  that  have  a full thickness standard corneal. This occurs because the natural surface of the cornea  is not replaced  so the focusing power  of the cornea remains more natural than with a full thickness corneal  transplant.  Of the patients  in our DLEK  program  that have  had  a PK  in one eye years ago and a DLEK or DSEK  transplant  in the other eye recently, most have stated that the quality of vision of the EK eye is superior to the quality of the vision in the PK eye. This has  been true even when  the PK eye measures 20/20 vision and the EK eye measures slightly worse  at 20/25  or 20/30  vision.  This  subjective  preference  by the patient  for the DLEK/DSEK/DMEK eye is currently being studied, and preliminary data indicates that patients subjectively prefer the DMEK eye over the DSEK eye when they have one of each.
2. The  one to three tiny  sutures  that  are used in these EK procedures  to close the scleral  or corneal  wound are  not  irritating. Patients who have a standard full thickness corneal. transplant  require either 16 sutures or one to two long looping sutures in a circle, all of which cause more discomfort  and more irregularity to the surface than has been shown with the DLEK/DSEKDDMEK technique.
3. If the endothelial cells that are  transplanted by this split thickness corneal transplant function normally as expected, then the cornea will lose its swelling and become clearer at a much faster rate than with a standard full thickness  corneal transplant.
4. A smoother surface for focusing and a clearer transplant has allowed many of our patients to see better  in a matter of weeks as compared to months or years with a standard  full thickness corneal transplant.
5. Because there are no sutures in your surface cornea in this study, the cornea  is stable more quickly than with a full thickness corneal transplant requiring less changes of glasses than a full thickness corneal transplant. Also, after full thickness corneal transplant,  up to 20% of patients  require a contact lens to see and cannot simply wear glasses. After DSEK or DMEK  surgery, over 98% of patients are able to obtain excellent  vision  without  the need for contact lenses.
6.  Because the corneal surface remains smooth and relatively unchanged from the curvature before transplant  surgery, there is expected to be better matching between the focusing power of your lens (or the artificial lens you received  at the time of cataract surgery) and the focusing  of the  surface of your cornea (This is what we have found in our protocol study patients.) Therefore  there  is  less of a chance of requiring thick glasses after transplant surgery with the DMEK/DSEK technique compared to full thickness corneal transplant surgery of PK.

Alternative procedures or treatments

You do not have to have a DMEK technique surgery to receive a corneal transplant.  Your surgery can be done with our previous DSEK technique or with a standard full thickness  corneal transplant (PK).

Unavailability of a Donor Cornea for the DMEK Program

In the unlikely event that a donor cornea  is not available or the donor cornea is damaged  during the preparation  process,  your surgery would  have to be cancelled  and rescheduled. This may occur on the day of surgery but prior to the start of anesthesia.

Costs

The Cornea Service at Devers Eye Institute, St. Vincent Hospital, or Good Samaritan Hospital will not pay for any of the costs of your medical care. The surgery and all of your follow up care would be needed whether you had PK, DSEK or DMEK transplant surgery. Therefore, these costs will be yours or your insurance company’s responsibility. Pre-authorization will  be obtained from you insurance  company to cover the costs of this surgery in the same manner that they would cover for the cost of a routine full thickness corneal transplant surgery. DSEK or DMEK are considered  to be simply  another  less  invasive form of PK surgery, and  is billed in the same manner as routine standard PK surgery, albeit with a billing  code that is specifically designated by Medicare for this form of endothelial keratoplasty. Over the long term, because DSEK and DMEK surgery have no corneal sutures or incisions to worry about, it is expected to cost much less in follow-up care than a standard PK surgery. This ultimately saves the patient and his insurance company a substantial amount of money.

Related Injury

Just as is the case with any surgery, you are responsible  for the costs of your medical care for injury resulting from treatment; however, these costs may be covered, at least in part, by most major insurance companies or Medicare. Providence Health System and Legacy Health  System will not assume financial responsibility for such treatment or provide financial compensation for such injury. Should you suffer any injury as a result of DSEK/DMEK surgery, emergency treatment will be available.