Overview of Limbal Epithelial Transplant

In 2012, a new procedure called Simple Limbal Epithelial Transplantation (SLET) was introduced by Sangwan and his team. It was designed to treat a problem called Limbal Stem Cell Deficiency (LSCD). This is a condition that affects the cornea, which is the clear front part of the eye.

In SLET, a small section is taken from the healthy part of the patient’s other eye (called the limbus), and then cut into 8-12 smaller pieces. These smaller pieces are then transplanted to the affected eye, after any abnormal corneal front skin and scar tissue are removed. To help these transplants stick to the eye, a special material called an amniotic membrane is placed onto the cornea, and then the small pieces are attached to it. After this, a special kind of contact lens called a bandage cornea lens is put on the eye.

The amniotic membrane is a great help in this procedure because it is capable of promoting the growth of stem cells and other cells that the front of the eye needs. This encourages the new cells to grow before any inflammation and scarring can stop regeneration.

There’s also a version of this procedure called Allogeneic SLET. It’s very similar to the original SLET, but it uses pieces from the eyes of either living donors or people who have passed away, instead of from the patient’s own eye. This version can be used for people who have the cornea problem in both eyes. Regardless of whether the tissue comes from a living person or someone who has passed away, the results seem to be the same.

Allogeneic SLET is also used in emergency situations, such as when someone has been exposed to a harsh chemical that can harm the eye’s surface.

After the Allogeneic SLET, patients will need to take medications to help their bodies accept the new tissue. These medicines suppress the immune system, and are often given through an IV. Long-term, these patients usually take a medication called cyclosporine, as well as eye drops that contain steroids.

While Allogenic SLET has the disadvantage of needing these immune-suppressing medications, it is still an option for those who can’t have regular SLET due to having the cornea problem in both eyes, or because of a systemic problem or injury.

Anatomy and Physiology of Limbal Epithelial Transplant

The surface of our eyes has two types of cells. The first kind is on the surface of the cornea (the front window of your eye), and the other is on the surface of the conjunctiva (the clear, thin film that covers the front part of the eye and the inside of the eyelids). There is a border between these two cell types called the “corneoscleral limbus.” This is also the place where the stem cells or “mother cells” live that can grow into new corneal cells. These cells are part of special structures known as “palisades of Vogt”. These structures are kept safe from harmful sunlight by pigmentation (coloring), and they offer a perfect place for the stem cells to live and function. You can see these structures on the eye surface if you were to use special eye equipment.

The “palisades of Vogt”, and therefore the stem cells, are found more in the top and bottom parts of the border and less on the sides. This could be because the eyelids give extra protection to these areas from damaging substances and harmful sunlight. The stem cells can grow and produce new cells that can then travel towards the center and front of the cornea and finally fall off the corneal surface. These new cells help keep the corneal surface healthy and also play the pivotal role in stopping the cells of the conjunctiva from invading the cornea.

There is a condition called Limbal Stem Cell Deficiency (LSCD), where these stem cells get depleted or don’t function properly. This can cause inflammation in the cornea, unwanted blood vessel growth, and the formation of an unusual tissue called pannus. LSCD can cause the conjunctival cells to invade the cornea and gradually transform it into an area filled with conjunctival cells. This can lead to the cornea being covered with unhealthy epithelium (layer of cells). If the stem cell damage is partial, then this unhealthy coverage will be incomplete and in severe cases, the entire cornea surface may be covered. Patients with LSCD might not feel any symptoms or could experience blurred vision, discomfort in the cornea, pain, recurring wounds on the epithelium, and infections.

LSCD can happen due to hereditary reasons or ones that you acquire. Acquired causes, or the ones you pick up during your lifetime, include chemical and thermal burns, contact lens overuse, surgery involving the limbus, exposure to harmful substances, type of corneal disease, and infectious disease of the cornea. It can be caused due to an overactive immune system resulting in conditions like Stevens-Johnson syndrome, mucous membrane pemphigoid, vernal keratoconjunctivitis, atopic keratoconjunctivitis, and graft-vs-host disease. Certain genetic conditions include congenital aniridia, xeroderma pigmentosa, dyskeratosis congenita, and epidermolysis bullosa.

Why do People Need Limbal Epithelial Transplant

Simple limbal epithelial transplantation (SLET), a type of eye surgery, has been proven effective in treating both total and partial LSCD, a condition that affects the transparent part of your eye called the cornea. For SLET to be done, you need to have one healthy eye from which limbal stem cells, cells that maintain and repair corneal tissue, can be taken. Most individuals needing SLET have suffered damage to one of their eyes due to accidents involving chemicals or excessive heat.

However, it’s important to note that SLET can only treat issues related to the epithelium, the surface layer of the cornea. If the deeper part of the cornea has been severely clouded or scarred, a different type of eye surgery (penetrating or lamellar keratoplasty) may need to be performed after SLET. An eye examination known as anterior segment optical coherence tomography can help determine how thick your cornea is and how much scarring or clouding is present.

Identifying LSCD can be tricky, as there isn’t any single test that all eye doctors agree on using. In many cases, the condition is determined based on the symptoms you’re experiencing. That said, impression cytology is often considered the most reliable test for diagnosing LSCD. This procedure involves taking a sample of cells from your cornea’s surface and checking for signs of unusual cells.

An easier and completely harmless test called fluorescein staining is also handy for diagnosing and monitoring LSCD. This test involves staining the surface of the eye with a yellow dye and looking for changes in the epithelium. The abnormal part of the epithelium absorbs the yellow dye slower than the normal part, even after being washed with eyewash solutions. The dye can also pool in areas where the epithelium is thinner, indicating areas of damage.

Lastly, looking for changes in the limbal palisades of Vogt, small, visible, and normally present structures in the limbus (the border area where the cornea meets the white of your eye), can also suggest LSCD. As we age, these structures might become smaller or disappear. However, if these changes are noticed in the upper part of your limbus, they can be indicative of stem cell loss in the cornea.

When a Person Should Avoid Limbal Epithelial Transplant

Simple Limbal Epithelial Transplantation (SLET), a type of eye treatment, may not be suitable for everyone. In particular, if a person’s limbal stem cell deficiency (LSCD) – a condition where the eye’s surface isn’t correctly repaired because of a lack of certain cells – is caused by an existing body-wide disease, SLET might not be the right choice. This is due to the fact that the process of gathering the required cells can end up causing more damage. Past trauma, infection, or surgery in the donor’s eye could also cause difficulties.

Wearing contact lenses has been shown to cause LSCD, although it’s typically less severe compared to other causes. But here’s a catch – in cases where the patient wears contact lenses, the SLET procedure could potentially lead to LSCD symptoms in the donor’s eyes as well.

In terms of bilateral LSCD, meaning if both eyes are affected, a different version of SLET that uses donated stem cells (allogenic SLET) may be an option. However, it does come with its own challenges as it requires long-term suppression of the immune system, which is not suitable for children.

There are also certain specific reasons why SLET might not be performed on the recipient’s eye:
– If the outer surface of the eye is too dry, shown by a specific test called Schirmer’s test.
– If the person is blind and there’s no chance of restoring vision.
– If the front part of the eye is disorganized due to issues like extensive scar tissue, bulging out of the eye, or white scar tissue sticking to the eye.
– If certain conditions affecting the eyelids and the tear duct system, such as being unable to fully close the eye, inflammation of the tear sac, inward- or outward-turning eyelashes and eyelids, are not treated.

Equipment used for Limbal Epithelial Transplant

To proceed with a medical procedure called simple limbal epithelial transplantation (SLET), which is a treatment to help repair the eye, certain types of equipment are necessary.

Firstly, the surgeon will need all the standard equipment found in an eye operating room. This includes various tools and devices that are specifically designed to aid in eye surgeries.

Secondly, they will need access to amniotic membranes. These are thin layers taken from the amniotic sac that surrounds a fetus in the womb. In this procedure, these membranes are used because they can help to promote healing in the eye.

Lastly, fibrin glue is needed. This is a unique type of medical adhesive made from proteins found in the blood. It’s used to help seal wounds and stick tissues together during surgery, reducing the need for stitches.

Who is needed to perform Limbal Epithelial Transplant?

A type of eye surgery known as Simple Limbal Epithelial Transplantation, or SLET, could be done by a team of medical professionals. This team includes an ophthalmologist or eye doctor, who leads the operation. They are helped by an assistant, a scrub tech who helps prepare and handover the necessary equipment, and a circulating nurse who works around the room to ensure everything goes smoothly. An anesthesiologist, a doctor who’s responsible for keeping you unaware and pain-free during the surgery, also plays a vital role.

The eye doctor is the one who performs the surgery and makes sure everything is done correctly. The whole team works together to make sure you’re comfortable, safe, and well taken care of throughout the entire process.

Preparing for Limbal Epithelial Transplant

If a patient has a condition called LSCD (Limbal stem cell deficiency), which affects the eye, it’s important to know all about their medical history. This is because their condition could potentially harm the healthy eye too. A test called fluorescein staining can help the doctor see any damaged areas of the eye that might need to be removed. For patients who only have LSCD in one eye, their other eye should be working fine.

Before any treatment is done, patients need to understand all the details and agree to the procedure. This includes letting them know they might need more than one operation to treat their condition. Another important point is that after undergoing a procedure called simple limbal epithelial transplantation (SLET), the treated eye may not look exactly like a normal one. So, it’s essential for patients to understand that the goal is to improve the condition of the eye, not necessarily to make it look completely normal again.

Prior to the surgery, patients are typically given eye drops that help to reduce bleeding during the procedure. This includes 2 to 3 drops of phenylephrine 5% and brimonidine tartrate 0.15% in both eyes.

In some cases, where transplantation of tissue from a cadaver is planned, there are specific criteria. Ideally, the donated tissue should be fresh (taken within 48 hours), visibly healthy, without any damaged cells, and taken from a cadaver who is 60 years old or younger.

How is Limbal Epithelial Transplant performed

Simple Limbal Epithelial Transplantation (SLET) is a surgical procedure to restore the eye surface area damaged due to chemical burns or certain eye disorders. Here is an explanation of the procedure using simple language.

Children would be put to sleep using general anesthesia. For adults, local or topical anesthesia is administered to numb the area around the eye undergoing surgery. As part of the process, a small piece (2-3 mm length) of healthy limbus (the border part between the eye’s clear cornea and white sclera) is removed. This flap of tissue is stored in a balanced salt solution for later use.

A 360° operation is performed on the damaged eye, and a special tool is used to remove the fibrovascular pannus, which is abnormal growth tissue over the cornea. In the operated eye, any normal healthy corneal and limbal tissue is left untouched. A thin, transparent film of amniotic membrane (the innermost layer of the placenta) is smoothed over the bare cornea, covering up to the edge of the spot where the earlier operation was carried out.

The healthy limbal tissue previously stored is cut into 10-12 equal pieces. These pieces are then placed onto the amniotic membrane just inside the limbus of the operated eye. It is unknown whether maintaining the original orientation of the grafts benefits the process, although some surgeons may attempt to do so. The grafts adhere (stick) to the amniotic surface with the help of fibrin glue, a substance used to keep tissues together. After this, a special covering (a bandage contact lens) is applied over the eye.

A particular case might require a certain suture technique known as tarsorrhaphy to avoid early loss of the graft or the contact lens. The patient’s eyes would then be treated with some medications to manage swelling until the suture is removed.

Suppose during the surgery it’s found that the corneal stroma, the part under the pannus, is too thin and ruptures. In that situation, a procedure called penetrating keratoplasty may be performed. This procedure involves transplanting a cornea from a donor. While it can be done simultaneously with SLET, it’s usually performed later because doing both at the same time could lead to the failure of the graft.

On the seventh day after the surgery, the lens used as a bandage is removed. If the healing is not complete, the lens is used for one more week. The healing of the donor eye is also monitored. Medications, in the form of eye drops, are given to prevent infection and manage inflammation in both eyes.

In cases, where the SLET uses tissue from a different source known as allogenic SLET, patients require long-term drug treatment to prevent the body from rejecting the grafts. These medicines administered to suppress the immune response may be given orally or through an IV drip. Regular health tests are necessary to monitor how the body is responding to these medications.

Various other surgical techniques include the Conjunctival Limbal Autograft (CLAU), Cultivated Limbal Epithelial Transplantation (CLET), Living-Related Conjunctival Limbal Allograft (LR-CLAL), and Keratolimbal Allograft (KLAL). Which technique is used depends on the patient’s condition and source of the limbal tissue. In all cases, the primary aim is to restore the eye’s surface area and help the patient regain vision.

Possible Complications of Limbal Epithelial Transplant

There are certain risk factors that could lead to problems with a procedure called simple limbal epithelial transplantation (SLET), which is a type of treatment for eye disease. These risk factors include: chemical burns to your eye, the presence of symblepharon (a condition where your eyelid sticks to your eyeball) before surgery, and undergoing penetrating keratoplasty (another kind of eye surgery).

Issues with the SLET treatment usually happen within six months after the surgery. It’s also important to note that complications in the donor eye (the eye from which the cells are taken for the treatment) are not typically seen.

The most common issue seen in the eye that receives the SLET treatment is a recurrent condition called Limbal Stem Cell Deficiency (LSCD). If this comes back but isn’t getting worse or affecting your vision, it can be monitored without additional treatment. If treatment is needed, repeating the SLET procedure has been successful.

Some other possible complications include bleeding under the amniotic membrane (a layer in your eye), which usually goes away on its own or can be drained using a needle puncture. Another potential complication is keratitis (an inflammation of the cornea), which can be bacterial or non-infectious. This could occur but usually responds well to treatments such as topical antibiotics. If the cornea appears cloudy or hazy, eye drops containing cyclosporine 0.05% can be prescribed to clear it.

There are also potential complications that may lead to the SLET graft (the transplanted tissue) failing, such as progressive conjunctivalization (growth of the conjunctiva over the cornea), symblepharon (the eyelid sticking to the eyeball), and loss of the tissue that was donated.

Some rare complications could include the growth of new blood vessels on the cornea (corneal neovascularization), cell overgrowth (epithelial hyperplasia), and Persistent epithelial defects (PED). Lastly, if the tissue for SLET is donated from another person (allogenic SLET), there is a risk of immune rejection, but it can be treated by increasing the dose of immunosuppressant medications.

What Else Should I Know About Limbal Epithelial Transplant?

There was a study conducted by Basu and his team on the long-term effects of a simple procedure called limbal epithelial transplantation (SLET). It was aimed at individuals with a unique eye condition called unilateral Limbal Stem Cell Deficiency (LSCD). The study involved 125 participants, 65 adults and 60 children. The results were highly encouraging, with 76% of the patients showing a positive response. One year on, the success rate was 80% for the adults and 72% for the children. Another similar study, conducted by Vazirani and his team, reported a success rate of 83.8% after six months.

When compared to other surgeries to treat LSCD, SLET holds some key benefits. It uses less donor tissue than Conjunctival Limbal Autograft (CLAU), another type of treatment for LSCD. Additionally, it is a simpler and more affordable process which doesn’t require a laboratory and is done in a single stage.

To further explore these differences, a review was made of 22 studies involving 1023 eyes to compare the results of SLET, CLAU, and another technique called Cultivated Limbal Epithelial Transplantation (CLET). The findings showed that SLET and CLAU had better results than CLET. Success rates were at 78% for SLET, 81% for CLAU, and only 61.4% for CLET. However, it’s important to note that the group assessing CLET was smaller and the study was of lower quality, which could influence these results.

Frequently asked questions

1. How does the Limbal Epithelial Transplant procedure work? 2. What are the potential risks and complications associated with the procedure? 3. How long does the recovery process take after the transplant? 4. Will I need to take any medications after the procedure? If so, what are the potential side effects? 5. Are there any alternative treatments or procedures that I should consider?

Limbal Epithelial Transplant (LET) can help individuals with Limbal Stem Cell Deficiency (LSCD) by restoring the damaged or depleted stem cells in the cornea. LET involves transplanting healthy limbal stem cells from a donor or from another part of the patient's eye to the affected area. This procedure can improve corneal health, prevent conjunctival cell invasion, and alleviate symptoms such as blurred vision, discomfort, pain, recurring wounds, and infections associated with LSCD.

You may need Limbal Epithelial Transplant (SLET) if you have limbal stem cell deficiency (LSCD), which is a condition where the eye's surface is not properly repaired due to a lack of certain cells. SLET can help restore the function of the limbal stem cells and improve the health of the eye's surface. However, there are certain situations where SLET may not be suitable, such as if the LSCD is caused by an existing body-wide disease or if there are complications in the donor's eye. Additionally, SLET may not be performed if the recipient's eye has certain specific conditions, such as dryness, blindness with no chance of restoring vision, disorganization of the front part of the eye, or untreated issues with the eyelids and tear duct system.

A person should not get a Limbal Epithelial Transplant (SLET) if their limbal stem cell deficiency (LSCD) is caused by an existing body-wide disease, as the process of gathering the required cells can cause more damage. Additionally, if the person wears contact lenses, the SLET procedure could potentially lead to LSCD symptoms in the donor's eyes as well.

The recovery time for Limbal Epithelial Transplant is typically around 7 days, at which point the bandage contact lens used during the procedure is removed. However, complete healing may take longer depending on the individual and the extent of the eye damage. Medications, such as eye drops, are given to prevent infection and manage inflammation during the recovery period.

To prepare for a Limbal Epithelial Transplant, the patient should undergo a thorough medical history evaluation to determine if they are a suitable candidate for the procedure. They should also have an eye examination, including tests such as fluorescein staining and Schirmer's test, to assess the condition of the eye and determine the extent of the damage. Additionally, the patient may be given eye drops to reduce bleeding during the surgery.

The complications of Limbal Epithelial Transplant (SLET) include Limbal Stem Cell Deficiency (LSCD), bleeding under the amniotic membrane, keratitis, conjunctivalization, symblepharon, loss of donated tissue, corneal neovascularization, epithelial hyperplasia, Persistent epithelial defects (PED), and immune rejection in allogenic SLET.

The text does not provide specific symptoms that require Limbal Epithelial Transplant. However, it states that most individuals needing SLET have suffered damage to one of their eyes due to accidents involving chemicals or excessive heat.

There is no specific information available in the provided text regarding the safety of Limbal Epithelial Transplant (SLET) in pregnancy. It is recommended to consult with a healthcare professional or ophthalmologist for personalized advice and guidance regarding this procedure during pregnancy.

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