What is the Cornea?
The cornea is the transparent part of the front of the eye. It is the first part of the eye to capture light and is responsible for a large portion of our vision. When the cornea is damaged by injury or disease it can lead to loss of vision or sometimes even blindness. Our corneal & external disease specialists are fellowship-trained in the latest procedures and treatments for corneal disease.
There are many different corneal diseases. Some are caused by bacterial, fungal or viral infections, while some are hereditary or develop over time.
Carolina Eyecare Physicians offers treatment for many corneal and external eye diseases, including:
- Scleritis (inflammation of the sclera, the white part of the eye)
- Keratitis (inflammation of the cornea)
- Corneal ulcers and abrasions
- Fuchs’ Dystrophy (cloudy morning vision)
- Keratoconus (deterioration of the cornea, leading to change of shape and loss of vision)
Scleritis, or inflammation of the sclera, can present as a painful red eye with or without vision loss. The most common form, anterior scleritis, is defined as scleral inflammation anterior to the extraocular recti muscles. Posterior scleritis is defined as involvement of the sclera posterior to the insertion of the rectus muscles.
Anterior scleritis, the most common form, can be subdivided into diffuse, nodular, or necrotizing forms. In the diffuse form, anterior scleral edema is present along with dilation of the deep episcleral vessels. The entire anterior sclera or just a portion may be involved. In nodular disease, a distinct nodule of scleral edema is present. The nodules may be single or multiple in appearance and are often tender to palpation. Necrotizing anterior scleritis is the most severe form of scleritis. It is characterized by severe pain and extreme scleral tenderness. Severe vasculitis, as well as infarction and necrosis with exposure of the choroid, may result from a rare form of necrotizing anterior scleritis without pain can be called scleromalacia perforans. The sclera is notably white, avascular and thin. Both choroidal exposure and staphyloma formation may occur.
Posterior scleritis, although rare, can manifest as serious retinal detachment, choroidal folds, or both. There is often a loss of vision as well as pain upon eye movement.
Keratitis is a condition where the cornea—the clear, round dome covering the eye’s iris and pupil—becomes swollen or inflamed, making the eye red and painful and affecting vision. Keratitis is also known as a corneal ulcer.
Some forms of keratitis may involve infection, including bacterial keratitis, viral keratitis, fungal keratitis, and parasitic keratitis. Contact lens wearers need to remember that infectious keratitis can result from not caring for your contact lenses properly.
A non-infectious form of keratitis may be caused by a simple fingernail scratch or from wearing your contact lenses too long.
Whatever form of keratitis you may have, it is crucial that you see an ophthalmologist right away. Waiting to have your keratitis diagnosed and treated can lead to serious complications, including blindness.
What Causes Keratitis?
Keratitis or corneal ulcer causes can include:
- Bacterial infection
- Viral infection
- Fungal infection (from plant material in the eye)
- Parasitic infection
- Improper cleaning and/or care for contact lenses
- Wearing contact lenses too long
- Injury (scratch)
- Vitamin A deficiency (rare)
Keratitis or corneal ulcer treatment depends on the type and severity of this corneal problem. Antibacterial or antifungal eye drops may be used to treat corneal infections. Sometimes steroid eye drops may be necessary to reduce the inflammation (swelling) of keratitis.
If the cornea is severely scarred or thinning has occurred, a corneal transplant may be needed to restore vision.
It is important to remember that keratitis must be treated early to reduce the risk of complications, and it is likely that frequent visits to an ophthalmologist may be needed to fully treat this corneal problem.
What Causes Corneal Ulcers?
You can prevent many causes of corneal ulcers. Use the correct protective eyewear when doing any work or play that can lead to eye injury. And if you wear contact lenses, it is important to care for your contact lenses correctly.
Corneal ulcers are usually caused by the following types of infections:
Bacterial infections. These are common in contact lens wearers, especially in people using extended-wear lenses.
Viral infections. The virus that causes cold sores (the herpes simplex virus) may cause recurring attacks. These attacks are triggered by stress, an impaired immune system, or exposure to sunlight. Also, the virus that causes chickenpox and shingles (the varicella virus) can cause corneal ulcers.
Fungal infections. Improper use of contact lenses or steroid eye drops can lead to fungal infections, which in turn can cause corneal ulcers. Also, a corneal injury that results in plant material getting into the eye can lead to fungal keratitis.
Parasitic (Acanthamoeba) infections. An Acanthamoeba is a microscopic, single-celled amoeba that can cause human infection. They are the most common amoebae in freshwater and soil. When Acanthamoeba enters the eye it can cause a bad infection, particularly for contact lens users.
Other causes of corneal ulcers include:
Abrasions or burns to the cornea caused by injury to the eye. Scratches, scrapes, and cuts can become infected by bacteria and lead to corneal ulcers. These injuries can happen from fingernail scratches, paper cuts, makeup brushes, and tree branches. Burns caused by corrosive chemicals found in the workplace and at home can cause corneal ulcers.
Dry eye syndrome.
Bell’s palsy and other eyelid disorders that prevent proper eyelid function. If the eyelid does not function properly, the cornea can dry out, and an ulcer can develop.
What Is Fuchs’ Dystrophy?
Fuchs’ dystrophy is a disease of the cornea. It is when cells in the corneal layer called the endothelium die off. These cells normally pump fluid from the cornea to keep it clear. When they die, fluid builds up and the cornea gets swollen and puffy. Vision becomes cloudy or hazy.
Fuchs’ dystrophy has two stages. In the early stage (stage 1), you may notice few, if any, problems. Vision is usually hazy in the morning but gets better throughout the day. This is because your eyes normally stay moist when they are closed during sleep. But when you are awake, the fluid dries normally.
With later stage 2, vision remains blurry all day. Too much fluid builds up during sleep and not enough dries up during the day. Also, tiny blisters may form in the cornea. The blisters get bigger and eventually break open, causing eye pain.
People in their 30s and 40s may have Fuchs’ dystrophy but not know it. Vision problems might not appear until age 50 or later. Women are more likely than men to have Fuchs’ dystrophy.
In the later stage (stage 2), your blurry or hazy vision will not get better as the day goes on. Here are other symptoms:
- Sandy or gritty feeling in your eyes
- Eye pain from the tiny blisters in the cell layer of the cornea
- Being extra sensitive to bright light
- Eye problems get worse in humid areas
- Very blurry or hazy vision from scarring at the center of the cornea
Fuchs’ Dystrophy Diagnosis
Your ophthalmologist will look closely at your cornea and measure its thickness. This is called a pachymetry. They will also check for tiny blisters. Using a special photograph of your cornea, your ophthalmologist may count the cells in your endothelium.
Fuchs’ Dystrophy Treatment
There is no cure for Fuchs’ dystrophy. However, you can control vision problems from corneal swelling. Your treatment depends on how Fuchs’ dystrophy affects your eye’s cells.
Here are treatments for early Fuchs’ dystrophy:
- Use an eyedrop medicine or ointment to reduce swelling of the cornea’s cells.
For very poor vision or scarred corneas, you may need a cornea transplant. This surgery could be one of two types:
- Endothelial keratoplasty (EK): Healthy endothelial cells are transplanted into your cornea.
- Full corneal transplant: The center of your cornea is replaced with a healthy donor cornea.
Your ophthalmologist will discuss what treatments are best for your condition.
What Is Keratoconus?
Your cornea is the clear, dome-shaped window at the front of your eye. It focuses light into your eye. Keratoconus is when the cornea thins out and bulges like a cone. Changing the shape of the cornea brings light rays out of focus. As a result, your vision is blurry and distorted, making daily tasks like reading or driving difficult.
What Causes Keratoconus?
Doctors do not know for sure why people have keratoconus. In some cases, it appears to be genetic (passed down in families). About 1 out of 10 people with keratoconus have a parent who has it too.
Keratoconus often starts when people are in their late teens to early 20s. The vision symptoms slowly get worse over a period of about 10 to 20 years.
Keratoconus often affects both eyes and can lead to very different vision between the two eyes. Symptoms can differ in each eye, and they can change over time.
In the early stage, keratoconus symptoms can include:
- mild blurring of vision
- slightly distorted vision, where straight lines look bent or wavy
- increased sensitivity to light and glare
- eye redness or swelling
In later stages, keratoconus symptoms often include:
- more blurry and distorted vision
- increased nearsightedness or astigmatism (when your eye cannot focus as well as it should). As a result, you may need new eyeglass prescriptions often.
- not being able to wear contact lenses. They may no longer fit properly and they are uncomfortable.
Keratoconus usually takes years to go from early to late stage. For some people, though, keratoconus can get worse quickly. The cornea can swell suddenly and start to scar. When the cornea has scar tissue, it loses its smoothness and becomes less clear. As a result, vision grows even more distorted and blurry.
Keratoconus can be diagnosed through a routine eye exam. Your ophthalmologist will examine your cornea and may measure its curve. This helps to show if there is a change in its shape. Your ophthalmologist may also map your cornea’s surface using a special computer. This detailed image shows the condition of the cornea’s surface.
Keratoconus treatment depends on your symptoms. When your symptoms are mild, your vision can be corrected with eyeglasses. Later you may need to wear special hard contact lenses to help keep vision in proper focus.
Here are other ways that your ophthalmologist might treat keratoconus:
- Intacs. This is a small curved device that your ophthalmologist surgically puts in your cornea. Intacs help flatten the curve of your cornea to improve vision.
- Collagen cross-linking. Your ophthalmologist uses a special UV light and eye drops to strengthen the cornea. Doing this helps to flatten or stiffen your cornea, keeping it from bulging further.
- Corneal transplant. When symptoms are severe, your ophthalmologist may suggest a corneal transplant. Your ophthalmologist replaces all or part of your diseased cornea with healthy donor cornea tissue.
Do not rub your eyes!
With keratoconus, try to avoid rubbing your eyes. This can damage thin corneal tissue and make your symptoms worse.
If you have itchy eyes that cause you to rub, speak to your ophthalmologist about medicines to control your allergies.
The cornea is the clear, front window of the eye. It helps focus light into the eye so that you can see. The cornea is made of layers of cells. These layers work together to protect your eye and provide clear vision.
Your cornea must be clear, smooth and healthy for good vision. If it is scarred, swollen, or damaged, light is not focused properly into the eye. As a result, your vision is blurry or you see glare.
If your cornea cannot be healed or repaired, your ophthalmologist may recommend a corneal transplant. This is when the diseased cornea is replaced with a clear, healthy cornea from a human donor.
A human donor is someone who chooses to donate (give) his or her corneas after their death to people who need them. All donated corneas are carefully tested to make sure they are healthy and safe to use.
There are different types of corneal transplants. In some cases, only the front and middle layers of the cornea are replaced. In others, only the inner layer is removed. Sometimes, the entire cornea needs to be replaced.
Corneal Transplant Surgery Options
Full-thickness corneal transplant
Your entire cornea may need to be replaced if both the front and inner corneal layers are damaged. This is called penetrating keratoplasty (PK), or full thickness cornea transplant. Your diseased or damaged cornea is removed. Then the clear donor cornea is sewn into place.
PK has a longer recovery period than other types of cornea transplants. Getting complete vision back after PK may take up to 1 year or longer.
With a PK, there is a slightly higher risk than with other types of corneal transplants that the cornea will be rejected. This is when the body’s immune system attacks the new corneal tissue.
Partial thickness corneal transplant
Sometimes the front and middle layers of the cornea are damaged. In this case, only those layers are removed. The endothelial layer, or the thin back layer, is kept in place. This transplant is called deep anterior lamellar keratoplasty (DALK) or partial thickness corneal transplant. DALK is commonly used to treat keratoconus or bulging of the cornea.
Healing time after DALK is shorter than after a full cornea transplant. There is also less risk of having the new cornea rejected.
In some eye conditions, the innermost layer of the cornea called the “endothelium” is damaged. This causes the cornea to swell, affecting your vision. Endothelial keratoplasty is a surgery to replace this layer of the cornea with healthy donor tissue. It is known as a partial transplant since only this inner layer of tissue is replaced.
There are a few types of endothelial keratoplasty. They are known as:
- DSEK (or DSAEK)
Each type removes damaged cells from an inner layer of the cornea called Descemet’s membrane. The damaged corneal layer is removed through a small incision. Then the new tissue is put in place. Just a few stitches—if any—are needed to close the incision. Much of the cornea is left untouched. This lowers the risk of having the new cornea cells being rejected after surgery.
Some things to know:
- With DSEK/DSAEK surgery, the donor tissue may be easier to transplant and position because it is thicker than the donor tissue in DMEK surgery.
- In DMEK surgery, the donor tissue is thin and can be more difficult to transplant. But recovery is quicker because the transplant tissue is thinner.
- Your eye surgeon will choose the type of surgery based on your cornea’s condition.