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What is the Cornea?

The cornea is often described as the window of the eye. At the front of the eye there is a clear, round surface. This is called the cornea. The cornea may look simple, but it is actually a delicate piece of tissue made of complex layers and systems. It is also extremely important to healthy vision.  If you are suffering red eyes, blurred vision,  sensitivity to light or unusual eye pain, you may be suffering from a corneal condition.  Corneal conditions  include anything from keratoconus or Fuchs’ endothelial dystrophy, to other issues like corneal scarring. Pacific Eye Institute has a team of cornea specialists with  extensive backgrounds in anterior segment pathology, as well as comprehensive ophthalmology, and look forward to helping you solve your corneal issues!


The cornea is made up of five separate layers, each with its own important function:


This is the cornea’s outermost layer. Its primary function is to protect the inner layers from bacteria, dust, and water. It also provides a smooth surface to absorb oxygen and nutrients from tears which are then distributed to the inner layers of the cornea.

Bowman’s Membrane

The Bowman’s membrane is an extremely thin, clear film of tissue made of strong protein fibers called collagen. When injured, the Bowman’s layer has a high risk of scarring which can lead to vision loss.


Behind the Bowman’s layer lies the stroma. The stroma is the thickest layer of the cornea, making up about 90% of the corneal thickness. The stroma is composed of water and collagen which is important in maintaining its transparency and shape.

Descemet’s Membrane

Behind the stroma is the Descemet’s membrane. This thin, strong membrane protects against infection and injury and repairs itself easily after injury.


The endothelium is the innermost layer. This thin layer contains endothelial cells which are important in keeping the cornea clear. Fluid from inside the eye leaks slowly into the stroma. The endothelium is responsible for pumping excess fluid out of the stroma. Without a healthy endothelium, fluid would build-up, leading to swelling of the cornea and causing vision loss (a condition called Fuch’s dystrophy).

Common Cornea Diseases and Disorders

The cornea, while resilient, is also susceptible to many different diseases and disorders:

  • Dystrophies
  • Keratoconus
  • Fuch’s Dystrophy
  • Pterygium

Red Itchy Eyes – It May Be Allergies

Ocular Allergies, most commonly brought on by pollen, are a very common culprit for itchy red eyes. Eye Allergies do not generally require medical attention and are most commonly treated with antihistamines (a medication that can be purchased over-the-counter in oral or eyedrop form). However, if you suffer from excessive tearing, dry eyes, stinging, and burning, it’s always a good idea to visit your eye doctor. The team at Pacific Eye can help you address the underlying causes of your seasonal eye issues, and provide treatment plans aimed at keeping your vision in the best shape possible all year round.

Scratched Cornea and Corneal Scarring

The cornea is fairly resilient and heals quickly on its own after minor scratches and injuries. However, deeper injuries can lead to corneal scarring. Corneal scarring can lead to further problems and possible vision loss. If you have suffered an injury to the eye or are currently dealing with an ocular disease that can result in corneal scarring, it is important to be diligent with your eye care appointments.

Treatment for Corneal Scarring:

Some corneal scars do not affect vision; however, more severe scarring can distort your vision and cause light. Special contact lenses called scleral lenses may be used to correct vision. In some cases, the corneal scarring is so severe that a corneal transplant is necessary.

Inflammation of the Cornea

Keratitis is an inflammation of the cornea. The noninfectious type of keratitis can be caused by an injury or by wearing contact lenses for too long. Infectious keratitis is the result of bacteria, viruses, fungi, or parasites entering the eye. This can also be attributed to contact lens wearing, especially if poor hygiene is a factor. This infection is generally treated with antibacterial eye drops.


Pterygium is a non-cancerous growth on the front surface of the eye and may be caused by UV light exposure, dust, wind, and dry eye. It can appear as a pink or red growth on the white part of the eye and may continue to grow toward the pupil. If this happens or begins to cause discomfort, it can be removed. New technologies use donor amniotic grafts and tissue glue which increase comfort and speed recovery time.

Cloudy Eye Sight and Loss of Clarity

A corneal dystrophy is a condition in which the cornea loses clarity due to a buildup of materials which cloud the cornea. This type of condition is generally inherited and happens in otherwise healthy people. One Type of Dystrophy is:

  • Fuch’s dystrophy. Fuch’s dystrophy is a condition that causes corneal swelling and vision loss. This condition is caused by fluid leaking into the cornea as a result of weakened endothelial cells. The excess fluid causes the cornea to thicken, swell and become cloudy. This condition may also be treated with a corneal transplant.


Keratoconus is one of the most common corneal dystrophies in America. Keratoconus causes the cornea to become thin and bulge outward in a cone-like shape. This results in blurry, distorted vision that can worsen over time.

Keratoconus Treatment

Mild to moderate keratoconus is usually treated with eyeglasses or contact lenses.
In more severe cases, surgery may be required. It is important to monitor the progression of Keratoconus with regular checkups. We will work with you to find the best treatment options to give you the best vision possible.

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Corneal Cross Linking

The team at Pacific Eye Institute is now performing cross-linking procedures to strengthen and stabilize the shape of your cornea. The procedure aims to stop the cornea from getting thinner, weaker, and more irregular in shape. It is highly effective in slowing disease progression and stabilizing existing vision.

This is an in-office procedure that treats both keratoconus and post-LASIK corneal ectasia. In a short, painless procedure, our surgeon will work to increases the rigidness of the cornea’s surface by inducing additional cross-links between collagen fibers.

We gently remove the cornea’s epithelial layer and then applies riboflavin (B2) eye drops to the surface of the eye. Controlled ultraviolet light is then used to treat the eye. After the treatment, your eye doctor will apply a special contact lens to protect the eye and prescribe antibiotic and anti-inflammatory eye drops.

Corneal Transplant

If the cornea becomes damaged beyond repair, a corneal transplant may be necessary. This process works by removing all or part of the cornea and replacing it with healthy donor tissue from an eye bank. The corneal specialists at Pacific Eye Institute can assess the health of your cornea and make treatment recommendations:

  • Full-thickness corneal transplant (penetrating keratoplasty or PK) to replace the entire cornea
  • Partial thickness corneal transplant (Descemet’s Stripping Automated Endothelial Keratoplasty or DSAEK) which replaces the damaged section of the back inner layer of the cornea
  • Descemet Membrane Endothelial Keratoplasty (DMEK) is a partial-thickness cornea transplant procedure with selective removal of the patient’s Descemet membrane and endothelium, followed by transplantation of donor corneal tissue. DMEK as an advanced corneal transplant procedure, offering faster recovery times and better visual outcomes.

Tears and Your Cornea

Each time we blink, a thin layer of tears spreads over the eye. This tear film allows our eyelids to move smoothly over the corneal surface as well as prevents infection and promotes healing. The tear film consists of three components: an outer oily (lipid) layer, a middle water (aqueous) layer, and a bottom mucin layer. Each component of the tear film is important in overall eye health:

  • Lipid layer. The outermost oil (lipid) layer keeps tears from evaporating too quickly from the eye. When the oil layer is lacking, it leads to a condition called evaporative dry eye syndrome.
  • Aqueous layer. The middle aqueous layer nourishes the cornea and conjunctiva.
  • Mucin layer. The bottom mucin layer helps spread the aqueous layer over the eye, ensuring that the eye remains wet.

When a component of the tear film is not adequate, it can result in irritation and redness. Dry eye syndrome may also develop. The tear film is extremely important to eye health, so any prolonged dryness or redness of your eyes must be reported to your eye doctor.

Dry Eye Syndrome

Dry eye syndrome is extremely common. It occurs when the eye either cannot produce enough tears or produces poor-quality tears. Symptoms of dry eye syndrome generally include a feeling of dryness, redness, the feeling that something is in your eye, and pain in the eye. Mild to moderate dry eye symptoms can usually be managed with over-the-counter lubricating eye drops. Severe cases of dry eye syndrome should be treated by a doctor because prolonged dryness can cause more serious problems over a long period. To learn more about our dry eye treatment options and Lipiflow, visit our Dry Eye Pages

To learn more about cornea treatments in the Inland Empire, contact Pacific Eye Institute today to schedule an eye exam.

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