The cornea is the transparent membrane covering the front of the eye. Since light has to pass through it at the correct angle for a person to see, the cornea is extremely important. If a person has a corneal disorder or a corneal disease, their vision may become significantly impaired.
Definition & Facts
There are many different types of corneal disorders that arise when the cornea does not function correctly. These can include:
- Corneal abrasions occur when the outermost layer of the cornea is removed by eye trauma.
- Corneal dystrophy happens if cloudy material builds up in the cornea, and it is called Fuchs' dystrophy if it worsens with age.
- Corneal neovascularization is a disorder that causes blood vessels from the eye to grow across the cornea.
- A corneal ulcer is an inflammatory condition that harms multiple layers of the cornea, and it is most often caused by an infectious disorder called keratitis.
- Keratoconus is a type of disorder that causes the cornea to gradually degenerate with age.
Symptoms & Complaints
If a patient has dystrophy, keratoconus, or neovascularization, they have trouble seeing. At first, vision just seems blurred or fuzzy. Over time, it may begin to appear darker, and patients might see multiple blurred images.
Patients with Fuchs' dystrophy tend to have worse vision in the morning. Light sources may appear starry, streaked, or flared. Depending on the corneal disorder, patients might be sensitive to light and experience greater eye pain when exposed to light.
Keratoconus causes the cornea to appear cone-shaped. If a person has corneal neovascularization, the transparent membrane of the cornea will be overgrown with tiny blood vessels. A corneal ulcer causes multiple layers of the cornea to be removed, and this is a visible symptom during an eye examination.
Though the precise symptoms can vary depending on the specific corneal disorder a patient has, all corneal disorders are generally associated with pain, abnormal corneal appearance, and vision problems.
An abrasion is usually caused by a foreign object coming into contact with the eye, such as being poked by a finger, but abrasions can also occur over time due to wearing contact lenses for too long.
Corneal dystrophies tend to result from an inherited genetic mutation that causes lipids to accumulate in the cornea. Most ulcers are due to a bacterial infection like staphylococcus aureus, but they can also be caused by a severe injury like a chemical getting in the eye.
Corneal neovascularization is commonly caused by hypoxia resulting from contact lens wear. In these cases, contact lenses do not allow enough oxygen to reach the cornea. This causes the eye to grow blood vessels into the cornea to give it adequate oxygen.
Keratitis is any sort of infection of the cornea, which may be a herpes virus infection, bacterial infection, fungal infection, or parasitic infection. The primary cause of Fuchs' dystrophy is inherited genes that cause endothelial cells in the cornea to die as a person ages. Doctors still are not positive of the cause of keratoconus, but it seems to be a combination of genetic factors and environmental factors.
Diagnosis & Tests
The diagnosis of a corneal disorder typically requires an examination by an ophthalmologist or other doctor who specializes in diseases of the eye. Typically, the doctor will examine the patient's eyes under a magnified view to see what is causing the issue. They often use a slit lamp, which is a special instrument that shines a bright light into the eyes while magnifying the eyes. A doctor can use this to view the cornea and the space between the iris and cornea.
If the doctor suspects some sort of corneal infection, they may take a sample of tears to examine in a laboratory in order to detect the presence of bacteria or other microorganisms. If a patient is experiencing blurring of the cornea, a small portion of the tissue may need to be excised and examined under the microscope. A biopsy may show tiny structural changes that could indicate corneal dystrophy.
Treatment & Therapy
Mild corneal abrasions can often heal on their own. A patient will need to rest their eyes and avoid wearing contacts or eye makeup until the corneal abrasion heals on its own. Medicated eyedrops that contain analgesic ingredients can be helpful while waiting for the cornea to heal. If the cornea is infected, a doctor may also prescribe antibiotic eye drops to kill the infective organism. Viral corneal infections may be treated with oral antiviral drugs, but patients have a high risk of recurring infections.
Abnormal corneal tissue buildup can be removed with a phototherapeutic keratectomy procedure. The early stages of corneal dystrophy normally rely on preventing progression. Patients may use eyedrops to prevent swelling and wear contacts to correct vision issues. If the cornea is severely damaged, a corneal transplant may be needed to save the patient's vision.
Prevention & Prophylaxis
To avoid neovascularization and infections, patients should only wear their contacts for the recommended amount of time. A person should also thoroughly wash their hands with an antibacterial soap before touching their eyes.
Abrasions and some ulcers may be avoided by wearing protective eyewear while playing sports, landscaping, or handling chemicals. Proper hygiene should be practiced when applying and removing eye makeup.