Cornea Treatment
The cornea is the transparent, dome-shaped surface that covers the front of the eye. It plays a crucial role in vision by helping to focus light onto the retina, which is the light-sensitive tissue at the back of the eye.
It’s like your eye’s version of a windshield. It keeps debris, germs and more out. Its specific shape plays a key role in how your eyesight works and filters some ultraviolet (UV) rays.
Your corneas are just in front of a fluid-filled chamber of your eye called the anterior (forward) chamber, which contains the aqueous humor. Behind the anterior chamber are your iris and pupil, followed by the lens. Surrounding your cornea is the sclera (the white part of your eye).
Because corneas are the first line of defense for the surface of your eye, they’re also prone to injuries and damage. Fortunately, your corneas also have fast, effective self-repair abilities.
Corneal Conditions
Regular eye examinations are crucial for detecting and managing corneal issues early. Proper hygiene and protection from injuries and UV light can help maintain corneal health.
Layers of the cornea
Your cornea has six layers. They are:
- Epithelium. This is the outermost layer of the cornea. It’s a physical barrier between the inside of your eye and the outside world, and it’s incredibly sensitive to pain. Researchers estimate the cornea has about 300 to 600 times as many pain receptors as your skin. That sensitivity is protective. It makes you react strongly to stop or remove whatever’s hurting your eyes.
- Bowman’s layer. This is a tough layer made mostly of collagen. It’s there to provide structure and help your cornea hold its shape.
- Stroma. This is the thickest layer of your cornea. It strengthens your cornea structure and helps bend (refract) light and focus it onto your retinas.
- Pre-Descemet’s layer (PDL). Another name for this is “Dua’s layer.” Research indicates it’s airtight, which means it’s a very strong barrier separating the fluid inside your eye and the air from the outside world.
- Descemet’s layer. This layer is thin and stretchy but also remarkably strong. It’s important to your eye structure and helps protect the inside of your eye from injury and infection.
- Endothelium. This layer is mainly responsible for fluid balance in your cornea and the inside of your eye. It helps make sure there’s just enough water and fluid in the stroma for your cornea to work as it should.
Each layer has a specific job, but your cornea’s true strength comes from how the layers work together. The layers work like laminate glass (also known as “safety glass”) in car windshields. Laminate glass is two layers of glass with a sheet of thin, clear plastic between them. The plastic layer makes the whole piece much stronger (and sometimes, there are additional alternating glass and plastic layers to make it even stronger).
What is Keratitis?
Keratitis: Inflammation of your cornea that can either be infectious (microbial) or noninfectious. Infectious keratitis is called a corneal ulcer. Bacteria cause most instances of infectious keratitis. Other times, viruses, fungi and parasites may cause the issue. Many things cause noninfectious keratitis, including eye injuries and a range of conditions that dry out the surface of your eye.
Symptoms of keratitis include:
- Eye redness
- Eye pain
- Excess tears or other discharge from your eye
- Difficulty opening your eyelid because of pain or irritation
- Blurred vision
- Decreased vision
- Sensitivity to light, called photophobia
- A feeling that something is in your eye
What is Keratoconus?
Keratoconus is a condition of the eye in which the normally rounded cornea bulges outward into a cone shape. The cornea is the clear, central part of the front surface of the eye. It protects your eye and helps you focus for clear vision. You pronounce keratoconus as care-ah-ta-KO-nus.
Eye care providers normally find keratoconus during your teenage years or your 20s and 30s, but it can also start in childhood. In some cases, a provider will diagnose a mild case of keratoconus at a later age. The changes in the shape of the cornea occur over several years but happen at a more rapid rate in younger people.
How does Keratoconus affect your vision?
Keratoconus changes vision in two ways:
- As the cornea changes to a cone shape, the smooth surface also warps. The term for this is irregular astigmatism. Glasses can’t fully correct irregular astigmatism.
- As the front of the cornea steepens, your eye becomes more nearsighted. As a result, you may need new glasses more often.
Symptoms
The main symptoms of keratoconus include:
- Gradually worsening vision in one or both eyes. (Generally, keratoconus affects both eyes.)
- Having double vision when you look out of just one eye.
- Seeing halos around bright lights.
- Being sensitive to light. (The term for this sensitivity is photophobia.)
- Having vision that gradually becomes distorted. With distorted vision, straight lines might look curvy or bent, and objects don’t have their correct shape.
Management and Treatment
There are several methods for treating keratoconus, depending on how severe the condition is. Your eye care provider can help to decide which, if any, of these treatments may help you. Treatments include eyeglasses, contact lenses, implantable ring segments, corneal crosslinking and cornea transplant.
What are Dry Eyes?
When your eyes are unable to stay properly lubricated, they may become dry. Dry eyes can increase your risk for an inflamed cornea (keratitis), cornea eye disease or eye infections such as pink eye (conjunctivitis), corneal ulcers and injuries, as well as vision disturbances. The most common symptom of dry eye syndrome is a scratchy or sandy feeling as if something is in the eye. Eye redness, blurriness, burning, itchiness, sensitivity to light and eye strain are also commonly reported symptoms.
The Importance of Tears for Your Eye Health
The production, make-up, distribution and drainage of tears play an important role in keeping the surface of your eyes healthy. Tears are made of three main components: oil (lipid), water (aqueous) and mucin (mucous). Although seemingly simple, a tear’s composition is quite complex. An imbalance within or between the layer’s components can lead to the decreased production of tears. If these components are not in proper balance, the ocular surface will suffer from dry eye symptoms.
Best Treatment for Dry Eyes
The best treatment for dry eyes is unique to each individual. If you feel you may be suffering from dry eye, it is first important that you be evaluated by a cornea specialist. Dry eye symptoms left untreated can lead to corneal scarring and other corneal issues. Agarwal Eye Hospital has cornea experts. When you come in for your appointment, you will receive a comprehensive eye exam. During your exam, your cornea specialist may order additional advanced testing to further examine your tear concentration (osmolality) and quality (diagnostic staining), production (Schrirmer’s test), and rate of evaporation (tear film breakup time). From there, you and your cornea doctor can discuss possible dry eye treatment options in order to increase lubrication and reduce inflammation.
What is Conjunctivitis?
Conjunctivitis (pink eye) describes a group of diseases that cause inflammation of the conjunctiva resulting in discomfort and redness. The conjunctiva is a protective membrane that lines the under portion of the eyelid and covers exposed areas of the sclera, the outer white portion of the eye. The conjunctiva serves an important role in lubricating the ocular surface and defending the eye from allergens and infection. Tears containing proteins and antibodies protect the conjunctiva and allow it to properly function.
Symptoms of Conjunctivitis (Pink Eye)
Conjunctivitis is caused by bacteria, viruses, allergens, or other inflammatory conditions. While causes vary, symptoms may look similar for each form of conjunctivitis. Patients who have conjunctivitis are recommended to seek treatment from an eye doctor or a corneal specialist. Infectious conjunctivitis can be extremely contagious and may spread quickly. Allergic conjunctivitis presents mainly with symptoms of itchy eyes and are typically associated with an allergen such as pollen.
Symptoms of all conjunctivitis forms may affect the eye(s) in the following ways:
- Swelling
- Itching
- Burning
- Redness
- Eye pain
- Increased tearing
- Sensitivity to light
- Discharge or crusting of the eyelids
Patients with symptoms of conjunctivitis should see an eye doctor. What to do next depends on the type of conjunctivitis you have, but generally treatment will depend on the specific cause of conjunctivitis.
What is Corneal Transplant?
The cornea is the outer most portion of the eye which helps you see clearly. Made up of six layers, the cornea is quite strong and serves as the eye’s first defense against damage to the rest of the eye. While durable, the cornea is highly sensitive and susceptible to injury and diseases like keratoconus. While the cornea can repair itself after many injuries and diseases without surgery, those left untreated or more traumatic corneal injuries can lead to the need for a corneal transplant.
About Corneal Transplant Surgery
Typically, surgery is reserved for those suffering from severe corneal scarring, Fuchs’ Dystrophy and as a form of keratoconus treatment. Corneal transplants are considered when all other options have been exhausted, and eyeglasses and contact lenses are no longer a viable way to correct vision. While a last resort, however, corneal transplants are frequently performed worldwide. The chances of success for this operation have risen dramatically because of technological advances. Corneal transplantation has restored sight to many, who a generation ago would have been blinded permanently by corneal eye disease, injury, infection, or inherited disease or degeneration.
How does a corneal transplant work?
In corneal transplant surgery, the cornea surgeon removes a portion of the cornea and replaces it with a clear, healthy cornea, donated through an eye bank. There are three main types of corneal transplants differentiated by how many of the cornea’s layers need to be transplanted: penetrating keratoplasty (full thickness), lamellar keratoplasty (outer layers) and endothelial keratoplasty (inner layers). During corneal transplant surgery, anesthesia is used and patients are given topical eye drops to help increase comfort.
Following surgery, pain is usually mild for the first week and patients’ vision may be blurry for a period of time. The length of time it takes to see an improvement in vision and fully recover from a corneal transplant depends on the type of corneal transplant surgery performed. This can range from one month to one year. Common side effects that patients report after surgery are a foreign body sensation, scratchiness and blurriness. Your cornea specialist at Agarwal Eye Hospital will be there for you with any questions you may have about your recovery.
Types of Corneal Transplants
Penetrating Keratoplasty (Full Thickness) Cornea Transplant
Penetrating keratoplasty involves transplanting all layers of the cornea from the donor (full thickness). During penetrating keratoplasty, a circular button-shaped section of corneal tissue is removed from the diseased or damaged cornea. A matching button-shaped section of corneal tissue from the donor is then positioned and sutured into place. Following surgery, stitches are progressively removed about every six weeks and healing can take up to a year. Occasionally, a Laser Assisted Keratoplasty (LAK) utilizes a femtosecond laser at the eye bank to create a custom sized transplant for an individual patient.
Deep Anterior Lamellar Keratoplasty (DALK) Cornea Transplant
Deep Anterior Lamellar Keratoplasty is a cornea transplant procedure where the outermost layers of the cornea are replaced. This procedure can be used to treat deep anterior corneal abrasions and as a form of keratoconus treatment. There is preservation of the recipient patient’s own endothelial cells possibly making rejection episodes less likely.
Endothelial Keratoplasty Cornea Transplant
Endothelial keratoplasty, also known as EK, replaces only the innermost layer of the cornea called the endothelium layer and leaves the overlying healthy corneal tissue intact. For patients with disorders involving the innermost layer of the cornea, EK is the procedure of choice. With this method, the surgeon makes a tiny incision and places a thin disc of donor tissue on the back surface of the cornea. An air bubble is used to position the new layer into place. The small incision is self-sealing and typically no sutures are required.
Endothelial keratoplasty has several advantages over full-thickness penetrating keratoplasty. These include faster recovery of vision, minimal removal of corneal tissue, no related complications with sutures, and reduced risk of astigmatism, or an asymmetrically shaped cornea, after surgery.
The most common disease treated with this condition is Fuchs Endothelial Dystrophy (FED). Fuchs Dystrophy leads to a progressive loss of endothelial cells over time. Loss of these delicate cells can lead to corneal swelling known as corneal edema and cause the cornea to cloud. There are two versions of endothelial keratoplasty corneal transplant surgery: Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) & Descemet’s Membrane Endothelial Keratosplaty (DMEK).
Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) & Descemet’s Membrane Endothelial Keratosplaty (DMEK)
With both DSAEK and DMEK surgeries, an air bubble is used to secure the cornea within the eye after transplantation. Both surgeries require patients to lay on their back for a period of time following surgery. Not everyone is a candidate for these surgeries, and rest assured your corneal surgeon will discuss with you which corneal transplant option is most beneficial for you and answer any questions you may have.
How successful are corneal transplants?
As technology has advanced, the success of corneal transplants has as well. There are still significant risks, but the risk of complications varies depending on how many layers of the cornea are transplanted. Complications can include the body rejecting the donor corneal tissue (cornea graft rejection), eye infection, and problems associated with the use of sutures.
Fortunately, cornea graft rejection is a rare event, especially with endothelial keratoplasty. Transplant rejection occurs when the body’s immune system detects the donor cornea as a foreign body and reacts to it. Rejection signs may occur as early as one month or as late as several years after surgery. The surgeon will prescribe medication that can help prevent the rejection process. Should a transplant fail, corneal transplant surgery can be repeated.
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