Cornea Transplant procedures replace a damaged cornea with a donor cornea, restoring vision and eye health. The cornea, the outermost layer of the eye, plays a crucial role in focusing light and ensuring clear vision. Composed of multiple layers of thin, transparent cells, it remains invisible to the naked eye. The iris, the eye’s first visible structure, gives it color—typically brown, blue, or green.
Cornea DALK DSEK DMEK DWEK or DSO
What is a Cornea?
The cornea is the outermost part of the eye. It is made up of many layers of thin cells. It is clear, therefore we are not able to see it. The iris, the eye’s first visible structure, is typically brown, blue, or green.
The cornea is masterfully crafted by nature. Even the most expensive man-made lenses cannot match its accuracy of function and self-preservation. The smoothness and shape of the cornea is critically important to its proper functioning as well its transparency. If the cornea’s smoothness or quality changes, vision is compromised.
Though appearing as one clear membrane, the cornea has five distinct layers, each with a unique function. The slim outer layer, or epithelium, is a dependable obstacle against corneal infection. It normally has to be damaged before an infectious bacteria or virus can enter between the layers of the cornea. Just below this layer is a fibrous band called Bowman’s membrane. It is important for the integrity of the cornea.
The third layer called the stroma is constructed from collagen, a connective tissue. This forms eighty percent of the cornea. Besides collagen fibrils, there are cells called keratocytes. The density of the fibres is higher towards the Bowman’s membrane. Below the stroma is again a fibrous layer. This is termed as Descemet’s membrane. It is the scaffolding for the innermost layer of cells called Endothelium cells.
When endothelial cells are healthy and balanced, they function as a “pump-leak system” to provide nutrients for the cornea. In other words these cells allow nourishing fluid from inside the eye (liquid food) to leak into the cornea. After the corneal cells have actually been nourished, the cells pump the fluid from the cornea.
If the endothelial pump is compromised for any reason the cornea will certainly over hydrate as well as become hazy. This often occurs in patients with endothelial injury from complex cataract surgery or those with Fuchs’ Endothelial Dystrophy.
A corneal transplant works like replacing the windshield of a car. When driving at any time, clear windshield vision is essential. The windshield needs to be clear at all times. Dust or rain can impair our ability to see through it. Likewise the cornea has to be always kept clear.
Light travels through the clear cornea on its course toward the retina in the back component of the eye. A healthy, clear cornea is needed for perfectly clear vision. Sometimes, the cornea is referred to as the” window” to the eye. Disease or injury can damage the cornea, blocking light and reducing vision.
Cornea Transplant or Corneal Transplantation?
A cornea transplant replaces a diseased cornea with a donor cornea from a deceased person.
There are a wide number of individuals that suffer from a diseased or cloudy cornea. When the cornea struggles, light can’t pass through properly, causing blurry vision or blindness. An ophthalmologist determines the best treatment. Before a cornea transplant, the retina and optic nerve must be healthy.
Indications for Cornea Transplant
Any dense scarring or opacity in the cornea. This affects the vision and cannot be improved with glasses or contact lenses. We can classify the causes:
- Congenital – Opacity like Peters anamoly
- Degenerative – Keratoconus, Macular cornea degeneration, Fuchs dystrophy
- Trauma – Like central corneal injury
- Tumors – Keloid
- Pterygium which invades central cornea
- Post surgical – Pseudophakic Bullous Keratopathy.
Once confirmed, your doctor decides if this procedure is necessary.
Now, corneal transplantation is exactly what it sounds like. Your cornea is being transplanted with a new donated cornea. If a transplant is suitable and a donor cornea is available, it’s a viable option.
Types of Cornea Transplant
- Full thickness Cornea graft called Penetrating Keratoplasty or PK
- Lamellar Graft or LK
- DALK or Deep Anterior Lamellar Graft
- DSEK or Descemets Stripping Endothelial Keratoplasty
- DMEK or Descemet Membrane Endothelial Keratoplasty
- DWEK OR DSO – Descemets membrane stripping
Traditionally manual keratomes have been used. We have now started using femtosecond lasers to get better shape alignments.. This helps in increasing wound apposition, strength and at the same time decreasing induced astigmatism.
A cornea surgeon, like Rajesh Khanna, MD in Los Angeles, determines the best transplant type for you. Call him at (310) 482 1240 if you need to find what is BEST for you.
Why Choose a Cornea Transplant ?
There are many individuals that will wonder why they should choose a corneal transplant other than any other technique available. Well, this is a question that can only be answered with regards to your specific situation. It’s important to understand that everyone is different, and everyone will suffer with a different eye condition. Each condition will not require this type of technique. If thoroughly diagnosed and deemed suitable, this procedure offers significant benefits.
* The Benefits of Corneal Transplantation
One of the major benefits of corneal transplantation will be the fact that you can see again. Healing time is required, but with thorough diagnosis, the procedure is quick and restores vision.It’s important to note that with any type of procedure available, there can be complications; however, 99.9% of the people that have been diagnosed for this technique have successfully regained their eyesight to a positive degree.
Corneal transplantation offers a solution for corneal issues. Consult your eye doctor to assess its benefits.
Cornea transplant and Insurance Coverage
There are certain costs involved in cornea transplant procedure. They can be divided into
- Cost of the cornea from the eye bank
- Cost of the surgery center
- Surgeon fees
- Anesthetist fees
- Laser fees
- Preoperative measurements
- Follow up care
Usually medical insurance covers some or most of the cost. Vision Insurance does not apply to this procedure. She insurances have stopped covering costs for the Cornea graft. It is best to send us your medical insurance card in advance so we can check your coverage.
Preparing for the Cornea Transplant procedure
Surgeons, eye banks, and surgery centers coordinate to procure and prepare the cornea for transplant. It is imperative you do not try to reschedule the surgery unless its absolutely medically necessary.
On the day of the surgery wear loose clothes. Do not drink or eat anything for eight hours before the scheduled time. You will have intravenous fluids and anesthetic given.
After the Cornea Transplant procedure
You will be given certain important instructions as to how you should sleep, based on the exact procedure. These need to be adhered to for successful outcome.
DALK or Deep Anterior Lamellar Keratoplasty
What is DALK?
Deep Anterior Lamellar Keratoplasty. As the name suggests it is a type of keratoplasty or corneal transplantation. There have been traditionally two types of replacement of cornea with a cadaver cornea. Full thickness graft referred to as Penetrating Keratoplasty or PK. The other type less commonly used was Lamellar keratoplasty or LK, This is a partial thickness cornea graft. Learn about the Structure of Cornea.
DALK is hybrid between LK and PK. It goes deep where no LK has ever been before (language sounds like Star Trek, huh). It just stops short of the Descemets’ and endothelial layer.
Indications for the DALK procedure
DALK is indicated when the inner layers of the cornea is healthy but the superior layers have a pathology.
Keratoconus Specialist Near Me – In Keratoconus eye disorder the endothelium works but the collagen layer is weak. Keratoconus eye disease is present in younger people. DALK is a good choice in them. If the cornea has ruptured like in Hydrops than DALK may not be possible.
Corneal Dystrophies and superficial scars not treatable with PTK are good candidates for DALK. Scars may varied etiology like post PRK scars, post traumatic or post infective. In cases of herpetic scars it is recommended to wait six months after the active infection has subsided.
Steps in DALK Surgery
- Preparation of patients Cornea: The thickness of the host cornea is measured. Three fourths of this value is calculated. A cornea trephine is set to this thickness.
- A needle is introduced through the trephined edge till it reaches the descemets membrane. An air bubble is introduced till it spreads uniformly across the cornea.
- Lamellar dissection is done with a crescent knife to remove the trephine superficial cornea.
- An air bubble is introduced into the anterior chamber. The constant presence indicates the endothelium has not been perforated.
- The needle is reintroduced into the remaining cornea over the descemets membrane. A knife slits the remaining stroma of the cornea. This is than excised with corneal scissors.
- The donor cornea graft, without the inner layer, is placed on the bare Descemet’s membrane and secured with stitches.
Advantage of DALK Transplant
- Safer during surgical procedure as the eye is closed system. Therefore iris and other content of the eye cannot come out.
- The endothelium of the patient is preserved. The chances of endothelium rejection are avoided.
- Even after DALK procedure eye is more resistant to trauma.
- Induced astigmatism is less.
Disadvantage of DALK
- It is technically more difficult to perform
- It may be necessary to convert it to PK on the operating table.
- The host donor junction can become hazy affecting the best corrected vision.
What exactly is DSEK or Descemet’s Stripping Endothelial Keratoplasty?
Some diseases of the cornea, however, just affect the inner lining of the cornea. A newer corneal transplant method, Descemet’s Stripping Endothelial Keratoplasty (DSEK), uses a thin corneal section for transplant. In DSEK, the diseased posterior cornea is replaced with a healthy graft from a donor.
Unlike the Penetrating Keratoplasty (PK), the DSEK treatment uses only a partial thickness graft. Therefore it requires a much smaller surgical cut and also requires no corneal sutures. This allows for faster visual recovery and lowers the risk of complications compared to PK surgery.
Indications for DSEK or Descemets Stripping Endothelial Keratoplasty
When the corneal endothelium is stressed out, the endothelial cells come to be larger and also a lot more thin. When endothelial cells drop to 500–1000 cells/mm², the pump mechanism fails to keep the cornea clear. This may occur after prolonged complicated cataract surgery. This entity is termed as Pseudophakic Bullous Keratopathy.
When it comes to Fuchs’ dystrophy the endothelial cells additionally start producing product that makes Descemet’s layer thicker and opaque. Vision at some point deteriorates to a point where these people feel like they are looking through wax paper. Such clients are ready prospects for the DSEK treatment.
Advantages of DSEK or Descemet’s Stripping Endothelial Keratoplasty
There are a lot of major benefits of the DSEK operation in comparison to the normal corneal transplant operation.
- In PK there is a time when the eye is completely open. If the patient were to strain or cough the interior structure of the eye can prolapse forward. In hypertensive patients there is even the chance the retina may come out. This is called expulsive hemorrhage. In DSEK only a small wound similar to that used in cataract eye surgery is made.
- There are many stitches used in PK or penetrating graft. DSEK or Descemets Stripping Endothelial Keratoplasty is either stich less or only one or two sutures may be required
- The chances of rejection are much less in DSEK
- The induced Astigmatism in PK is high compared to the almost negligible amount in DSEK
- Integrity of the eye is better in DSEK than in PK
- Returning to an active lifestyle and resumption of uninterrupted work is faster with DSEK.
The healing with PK can be fairly long, up to twelve months. It is likewise not unusual to have significant irregular curvature of the cornea as a result of the stitches. In many cases a prescription lens is required to achieve the best vision. A full-thickness corneal transplant may remain fragile for years, with minor trauma potentially displacing the graft. Cornea specialists have performed DSEK surgery for the past ten years with amazing success. Future endothelial transplant research will center on making the procedure more reliable and not as surgeon-dependent.
Steps of Descemet’s Stripping Endothelial Keratoplasty
The transplant tissue can be made manually by the corneal surgeons in the operating suite. This is done using a special punch and fine dissection. There is a chance of damaging the graft as it is a very delicate procedure. The trend has been to order premade graft from the eyebank. Technicians there do a large number of graft harvesting so they become adept at the procedure. In addition if the graft is damaged they can utilize another donated cornea to yield the graft.
If the patient chooses surgery, they must sign an informed consent form. You’re going to be awake during the process and the majority of people don’t report any discomfort. Dr. K routinely performs this treatment just utilizing eye drops to numb the eye. Some patients could be given local or general anesthesia, especially if their general medical condition is in question.
The DSEK procedure takes approximately 45 minutes to 1 hour. After the eye is prepped and draped in sterile fashion an eye retainer is inserted to keep the eyelids open. The Cornea specialist removes the unhealthy internal cell layer of the cornea. The surgeon implants healthy and balanced benefactor tissue through a tiny cut. Dr.Khanna after that utilizes an air bubble to unfold and place the donor tissue against the patient’s cornea. The small incision is either self-sealing or may be closed with a stitch or two.
Most patients have minimum pain after surgery. Patients lie flat in recovery for 45–60 minutes and are examined before discharge. For the first 24 hours, they should stay on their back, facing the ceiling as much as possible.
They start to see once the bubble dissolves over the subsequent 2-3 days. They can return to normal activities a week or two following surgery.
Alternatives to DSEK or Descemets Stripping Endothelial Keratoplasty
Damaged corneal tissue blocks light, causing poor vision or blindness. Patients with stromal scars need penetrating keratoplasty, not DSEK.
Full Thickness Penetrating Keratoplasty and Lamellar Thickness Keratoplasty have preceded DSEK. Another newer procedure where only Descemet’s is removed is called DWEK. It has only limited indication in certain Fuchs patients. ROCK inhibitors have to be used.
More popular and a finer procedure is DMEK. Here as shown in the picture an even thinner graft is used. The graft here is one tenth the thickness of DSEK.
DISADVANTAGES OF DSEK TECHNIQUE
A unique risk of DSEK, unlike conventional transplants, is graft dislocation, where the disc shifts from its position.
In this circumstance the donor disc needs to be repositioned in the operating area. If the air bubble escapes the graft may get dislodged requiring another air bubble. The interface between the host and donor is not completely smooth. This may limit vision in few individuals. DSEK also adds more tissue than it removes. It may result in a hyperopic shift.
Here is a DSEK eye surgery video.
When choosing a Los Angeles DSEK surgeon, select a cornea specialist with expertise. They will determine if a DSEK transplant is right for you.
DMEK or Descemet’s Membrane Endothelial Keratoplasty
DMEK or Descemet’s Membrane Endothelial Keratoplasty is the latest advancement in corneal transplant surgery. It is a newer variant of DSEK corneal surgery. It involves transplanting only the inner 15 microns of the cornea.
Indications for DMEK
DSEK is recommended for Fuchs’ dystrophy, Pseudophakic Bullous Keratopathy, and other corneal diseases affecting the innermost layer. A prerequisite is that the rest of the cornea should be healthy. If there is opacity in the center of the cornea than a full thickness graft may be more appropriate. Handling this ultra thin graft requires a high level of dexterity. This behooves a clear view beneath the cornea. The upper layer of the cornea called the epithelium can be removed to improve clarity.
THE DMEK PROCEDURE
The procedure consists of three parts. Harvesting the graft from the donor cornea is the first step. Next the recipient cornea is prepared to receive the graft. Finally the endothelial graft is introduced into the patients eye and made to stick to the cornea.
STEP 1 OF DMEK
The donor cornea is put endothelial side up in a punch like a Moria disposable punch. A dull instrument is used to separate the descemets from the schwalbes’ line. When approximately 60 percent has been cleaved the corneal button is centered over four holes. It is then stained with trypan blue. It is than punched with a 7.5 mm to 8 mm trephine. The descemets is separated from the rest of the cornea. It is soaked in trypan blue and covered. Attention is than directed to the patient.
Nowadays surgeons are preferring to obtain a precut preloaded prepared graft. This graft already has a mark to determine its orientation.
STEP 2 OF DMEK PROCEDURE
The patients eye is prepped and draped. Some surgeons proceed with topical anesthetic drops. Others prefer to perform a retrobulbar block to prevent eye movements. A speculum is inserted. The center of the cornea is identified. A ring of 8mm is placed over it. The indentation are marked with a marking pen. Two 1 mm paracentesis incisions are made. Viscoelastic is injected in the eye.The main temporal wound is 3 to 5 mm . A reverse sinksy instrument scores the descemets’ and endothelium along the preinked corneal marks. This tissue is than stripped off. A forceps grabs it. It is than placed over the cornea to confirm it is uniform. Also the inner cornea is inspected to detect if there are any strips of the tissue left behind. An opening is made in the iris at 6 or 9 o’clock. If all is fine the viscoelastic is removed. Any residual viscoelastic is an enemy to the donor graft says Dr.Khanna
STEP 3 OF DMEK
Now is the most challenging part. The graft is loaded into a specially designed bulbous glass device attached to a syringe. Hence the graft gets curled with the endothelial side up. This device is introduced into the temporal wound. With gentle pushes the graft is pushed into the anterior chamber of the eye. Then the dance begins as we want the graft to unfold. The cornea is gently tapped and rolling motions executed. An air bubble is introduced under the flap once it opens. The remarked S or F is identified to confirm it is right side up. Air is introduced to raise the pressure of the eye for next 10 minutes. Then some of the air is released. A subconjunctival injection of steroid and antibiotics is given.
Patient is transferred but made to lie flat on their back for the next hour. They are also instructed to do the same at home.
DWEK or DSO is a type of Corneal graft.
Well in a recent post we talked about DSEK and DMEK. These are alternatives to full thickness penetrating corneal grafts. They also may be called sutureless corneal graft.
Now one of the surgeons whose DMEK graft fell off discovered the cornea still healed. The realization dawned that removing just the diseased endothelium may all that is required in certain patients. This procedure is called DWEK or DSO. DWEK stands for Descemets stripping without Endothelial Keratoplasty. A more apt name may be DSO Descemets stripping only.
This is shown to work in few selected individual. The best candidate might be an older person with just central dense Fuchs guttate. Central 4 mm of endothelium is removed. The adjoining healthy cells migrate and take over the function of the unhealthy cells. The cornea clears and vision improves. This process can take 3-4 months.
DMEK clears up the cornea faster and is preferred in younger individuals. DSEK is the original procedure which involved removing of the unfit inner corneal cells. Actually all these surgical interventions are a continuum of inner corneal transplants. The difference being how much of the diseased cornea is removed. And whether a transplant is performed. If performed than the thickness may vary.
