What is the cornea
The cornea is the eye's outermost layer. It is a clear, dome-shaped surface that covers the front of the eye. It has two main functions:
- Protection – The cornea helps to shield the rest of the eye from germs, dust, and other harmful objects. The cornea also serves as a filter, screening out some of the most damaging ultraviolet (UV) wavelengths in sunlight. Without this protection, other parts of the eye might be harmed by UV radiation.
- Vision - The cornea acts as the eye's outermost lens. It functions like a window that controls and focuses the entry of light into the eye. When light strikes the cornea, it bends--or refracts--the incoming light onto the lens. The lens refocuses that light onto the retina, a layer of light-sensitive cells at the back of the eye. The retina then converts the light into electrical signals that it sends to the brain. The brain translates these signals into images.
Corneal Conditions
There are several common conditions that affect the cornea
- Refractive Errors: These issues including nearsightedness, farsightedness, and astigmatism affect how the cornea shapes light resulting in imperfect vision. You can read more about how we address these issues HERE.
- Injuries: Small abrasions on the cornea will typically heal on their own with time but deeper injuries will take longer to heal resulting in pain, blurred vision, tearing, redness, and extreme sensitivity to light. There is also the chance that a deeper injury will cause corneal scarring which might require a corneal transplant.
- Allergies: Allergies to pollen can irritate the eyes and cause allergic conjunctivitis (pink eye).
- Keratitis: Otherwise known as Corneal Infections, these infections can be a rare but serious complication of contact lens wear. They can reduce clarity of vision, cause corneal discharges, and even erode the cornea.
- Dry Eye: Dry eye occurs when your eye is unable to create enough tears to stay wet. This can be uncomfortable and cause vision problems. You can read more about how we address these issues HERE.
- Corneal dystrophies: Buildup of material within the cornea. These types of diseases are usually genetic.
Corneal Transplant
An improperly curved cornea may be corrected surgically or non-invasively to reduce or eliminate the need for eyeglasses or contact lenses. A thorough eye examination and consultation are necessary before a treatment decision can be made.
Transplantation involves replacing the damaged cornea with a healthy one from a donor (usually through an eye bank). Keratoplasty is a low-risk procedure – it is the most common type of transplant surgery and has the highest success rate.
During the procedure, a circular incision is made in the cornea. A disc of tissue is removed and replaced with healthy tissue; these discs may be thin (lamellar keratoplasty) or as deep as the entire cornea (penetrating keratoplasty, the technique used in almost all corneal transplants). Local or general anesthesia may be used. The entire procedure lasts only 30-90 minutes.
Allergies
Pollen, mold, dust, and pet dander are all common causes of allergies that affect the eyes. These allergies can lead to eyes that are red, itchy, and watery. If diagnosed with allergies it’s best to avoid going outdoors as much as possible when pollen counts are highest. Keeping windows closed and using air conditioning instead of window fans to limit the number of allergens in the air. Avoid rubbing your eyes as that will only irritate them more. These allergies can be relieved temporarily by washing allergens from the eye through the use of artificial tears which are available over-the-counter.
Keratitis
While not always connected, keratitis is typically caused through improper care of contact lenses. Symptoms of this infection are irritated or red eyes, worsening pain in or around the eyes, light sensitivity, sudden blurry vision, and watery eyes or discharge. It is always important to replace and care for your contacts as directed by your doctor to help minimize any risk of infection. Keratitis can be treated with medicated eyedrops depending on the type of keratitis developed.
Corneal Dystrophy
Most corneal dystrophies are progressive – the get worse over time. Some cause vision loss or pain, while others have no symptoms. The only way to know for sure if you have a corneal dystrophy is to get regular comprehensive eye exams. Some types of corneal dystrophies, such as keratoconus, can be treated with glasses or contacts lenses in mild cases but might require corneal transplant in more severe cases. Other types, such as Fuch’s dystrophy will require a regiment of eye drops or ointments that will help reduce corneal swelling.
