Common Corneal Diseases

Structure of the cornea diagram

The cornea is the front cover of the eye. It acts like a window to allow the image to enter the eye and helps focus it on the retina in the back of the eye. Therefore, it is a very important structure of the eye that has to stay moist and clear at all time. Many things can go wrong with the cornea ranging from common dry eyes, scratched cornea, infections, and vision-threatening conditions such as corneal ulcer, keratoconus, and Fuchs’ dystrophy.

Keratitis / Corneal Inflammation

Keratitis is an inflammation of the cornea. Keratitis can occur due to abrasion, trauma, infection, or underlying diseases such as Sjogren’s syndrome and lupus. Keratitis can lead to blindness.

Dry Eye Syndrome

Woman rubbing her dry eyes

What is Dry Eye Syndrome?

Dry eye syndrome (also known as dry eyes or keratoconjunctivitis sicca, KCS) is a very common condition that is caused by a disturbance of the tear film.  This abnormality may result in disruption of the ocular surface, causing a variety of symptoms that interfere with quality of life. 

A thin tear film coating the eye is made up of three layers:  the innermost mucous layer, the middle watery layer, and the outermost oil layer. Any disturbance in the balance of the components will lead to dry eye syndrome. 

What causes Dry Eye Syndrome?

Dry eye syndrome is a common disorder of the normal tear film that results from decreased tear production, excessive tear evaporation, and an abnormality in the production of mucus or oil normally found in the tear layer, or a combination of these.

  • Watery (aqueous) tear deficiency is caused by either poor production of watery tears or excessive evaporation of the watery tear layer. Poor production of tears by the tear glands may be a result of age, hormonal changes, or various autoimmune diseases, such as Sjögren’s syndrome, rheumatoid arthritis, or lupus.  Evaporative loss of the watery tear layer is usually a result of an insufficient overlying lipid layer.  Some medications, such as antihistamines, antidepressants, beta-blockers, and oral contraceptives, may decrease tear production.  If blinking is decreased or if the eyelids cannot be closed, the eyes may dry out because of tear evaporation. While reading, watching TV, or performing a task that requires close attention with the eyes, a person may not blink as often. This decreased blinking allows excessive evaporation of the tears. Certain conditions, such as stroke or Bell’s palsy, make it difficult to close the eyes. As a result, the eyes may become dry from tear evaporation.  Parkinson’s disease can decrease blink rate causing evaporative dry eyes.
  • Mucus (mucin) tear deficiency occurs in the conjunctiva. This can result from chemical (alkali) burns to the eye or because of different autoimmune diseases, such as Stevens-Johnson syndrome and cicatricial pemphigoid. This abnormal production leads to poor spreading of the tears over the surface of the eye. The surface of the eye can dry out and even become damaged, even though more than enough watery tears may be present.
  • Oil (lipid) tear deficiency is the result of meibomian (oil) gland dysfunction, rosacea, or following oral isotretinoin medication. Meibomian glands are the oil glands in the eyelids (with opening along the lash lines) that produce the lipid (oil) layer.

What are the dry eye syndrome symptoms?

Common symptoms are gritty/scratchy, or filmy feeling, burning or itching, redness of the eyes (conjunctivitis), blurred vision, foreign body sensation, and light sensitivity. The symptoms are worse towards the end of the day, in dry or windy climates, and in winter months.

How is dry eye syndrome diagnosed?

During an eye examination, the eye doctor will most likely be able to diagnose dry eye syndrome just by hearing the patient’s complaints about his or her eyes. Confirmation of the diagnosis can be made by seeing signs of dry eyes. As part of the eye examination, the following tests may be performed:

  • The front of the eyes is examined using a special microscope, called a slit lamp.
  • The amount and thickness of the tear film are inspected.
  • The stability of the tear film is assessed by checking the tear breakup time.
  • The conjunctiva is examined to determine if it is too dry.
  • The cornea is checked to see if it has dried out or become damaged.

How is Dry Eye Treated?

There is no cure for dry eye syndrome and some people have recurring episodes for the rest of their lives, but there are treatments to help control the symptoms. The exact treatment for dry eye syndrome depends on whether symptoms are caused by the decreased production of tears, tears that evaporate too quickly, or an underlying condition.

  • The first thing to consider is whether there are any obvious factors that could be changed, such as altering any medication that is causing symptoms.
  • If your dry eye syndrome is caused by an underlying medical condition, your medical doctor will prescribe treatment for it or will refer you to an appropriate specialist.
  • You may also be able to help prevent dry eye syndrome or ease your symptoms by adjusting your environment, keeping your eyes clean and improving your diet. Read more about treating and preventing dry eye syndrome below for specific treatment.

Lubricant Treatments

Woman putting in eye drops to help with dry eyes
  • Mild cases of dry eye syndrome can usually be treated using lubricant eye treatments that consist of a range of drops, gels and ointments. These lubricants are often called ‘artificial tears’ because they replace the missing water in the tear film. However, they do not contain the antibodies, vitamins and nutrients found in normal tears that are essential for eye health.
  • Moderate cases require more frequent use of artificial tears or thicker eye drops (gels). There are many different types of eye drops and gels, and it is often worth trying a number of different ones to find one that suits you. However, it is important you discuss any changes you wish to make to your treatment with your doctor.
  • Severe cases need frequent use of lubricants, more than 4-6 times a day. Preservative-free eye drops are more suitable because they do not contain preservatives that irritate the eyes with frequent use. If you wear soft contact lenses, you may also need to use a lubricant that is preservative-free, as preservatives attach to the contact lens and damage the eye. These types of eye drops may be more expensive.
  • ‘Oily’ tear eye drops replenish the oily part of the tear film and reduce evaporation from the surface of the eye. Oily tear drops are particularly useful if you have blepharitis (inflammation of the rims of the eyelids) or dry eye syndrome caused by your tears evaporating too quickly.
  • Eye ointments can also be used to help lubricate your eyes and help keep them moist overnight because your tears can evaporate while you sleep if your eyes are not fully closed. These ointments tend to be used overnight because they can cause blurred vision. If you wear contact lenses, do not use eye ointments while wearing them.

Anti-inflammatory Treatments

The underlying problem with long-term dry eye syndrome is inflammation in and around the eye. Therefore, one of the anti-inflammatory treatments mentioned below may also be recommended.

-Corticosteroid Eye Drops and Ointments

Corticosteroids are powerful anti-inflammatory medications that can be given as eye drops or ointments in severe cases of dry eye syndrome. They have side effects such as cataract formation and raising the pressure within the eye in about one in every five people. This group of treatments should only be used if you are being monitored by an eye doctor.  Common steroids in these groups are prednisolone acetate 1%, Lotemax, Tobradex.

-Oral Tetracycline

Low doses of a medication called tetracycline can be used as an anti-inflammatory agent for a minimum of three to four months, sometimes much longer. The most common tetracycline used is doxycycline.

-Cyclosporine (Restasis) Eye Drops

Cyclosporine is a medication that suppresses the activity of your immune system and is commonly used in the treatment of dry eye syndrome. The commercially available form of prescription cyclosporine eye drop is called Restasis.  It is used twice a day and requires up to 3 months to see improvement in dry eye symptoms.

-Autologous Serum Eye Drops

In very rare cases, where all other medications have not worked, autologous serum eye drops may be required. Special eye drops are made using components of your own blood. It is only available through a local compounding pharmacy. To make autologous serum eye drops, one unit of blood is taken under sterile conditions (as for regular blood donation). The blood cells are then removed and the remaining serum is put into eye drop bottles. Because of quality standards, this process can take several days before the treatment is finally available to use.

-Punctal Occlusion

Punctal occlusion involves using small soft plugs called punctal plugs to seal your tear ducts. This means your tears will not drain into the tear ducts and your eyes should remain moist.  In more severe cases, the tear ducts are cauterized (sealed using heat). This permanently seals the drainage hole to increase the amount of tears on the surface. This can be performed in combination with lubrication treatment.

Map – Dot – Fingerprint Dystrophy

What is Map-Dot-Fingerprint Dystrophy?

Map Dot Fingerprint Dystrophy

Map-Dot-Fingerprint Dystrophy (also known as Epithelial Basement Membrane Dystrophy or simply EBMD, and Cogan’s Dystrophy) is a disease that affects the top layer of cornea. It is commonly called Map-Dot-Fingerprint Dystrophy because of microscopic dot and fingerprint-like patterns that form within the layers of the cornea.

The cornea is comprised of five layers. EBMD affects the superficial corneal layer called the epithelium. The epithelial bottom, or basement layer of cells‚ becomes thickened and uneven. This weakens the bond between the cells and sometimes causes the epithelium to become loosened and slough off in areas. This problem is called corneal erosion.

Even though this disease is commonly known as a dystrophy (a term that describes genetic diseases), EBMD is not necessarily an inherited problem. It often affects both eyes and is typically diagnosed after the age of 30. Cogan’s usually becomes progressively worse with age.

Signs and Symptoms

Most patients with EBMD have no symptoms at all. The symptoms among patients may vary widely in severity and include:

  • Light sensitivity
  • Glare
  • Fluctuating vision
  • Blurred vision
  • Irregular astigmatism (uneven corneal surface)
  • Mild to extreme irritation and discomfort that is worse in the morning

Detection and Diagnosis

The doctor examines the corneal layers with a slit lamp microscope. In some cases, corneal topography (surface curvature map) may be needed to evaluate and monitor astigmatism (shape irregularity) resulting from the disease.


The treatment for EBMD is dependent on the severity of the problem. The first step is to lubricate the cornea with artificial tears to keep the surface smooth and comfortable. Lubricating ointments are recommended at bedtime so the eyes are more comfortable in the morning. Salt solution drops or ointments such as sodium chloride (Muro 128) nightly for several months are often prescribed to reduce swelling and improve vision. Gas permeable contact lenses are occasionally fitted for patients with irregular astigmatism to create a smooth, even corneal surface and improve vision.

For patients with recurrent corneal erosion, soft, bandage contact lenses may be used to keep the eye comfortable and allow the cornea to heal. In some cases, laser treatment may beneficial. The surgeon removes the epithelium with an Excimer laser (same laser used in LASIK surgery) to create a rough but regular surface (similar to sanding plank before painting). The epithelium quickly regenerates (similar to applying new paint), usually within a matter of days, forming a better bond with the underlying cell layer.

Fuchs (Corneal) Dystrophy

Cornea with Fuchs' Dystorphy

Fuchs’(pronounced fÅ«ks not fyooks) endothelial dystrophy is a non-inflammatory, autosomal dominant, dystrophy involving the endothelial (innermost) layer of the cornea. With Fuchs’ dystrophy the cornea begins to swell causing glare, halo, and reduced visual acuity. The damage to the cornea in Fuchs’ endothelial dystrophy can be so severe as to cause corneal blindness.

Eye examination shows cloudiness and swelling in the center of the cornea and roughness on the inner layer of the cornea. It appears like orange peel rather than the glossy apple skin. This makes it seem like looking through frosted glass.


General treatment is symptomatic. At this time there is no treatment to reverse or halt the progression of Fuchs dystrophy.

Medical therapy

Medical treatment of Fuchs’ dystrophy begins once patients notice fluctuation in vision. Typically, it is worse upon awakening and improves towards the end of the day as the eyes dry from air exposure between blinks. Here are the medical treatment options:

  • Hypertonic eye drop to pull fluid from the cornea is the early treatment option. Usually it is in the form of hypertonic saline drops and/or ointments (Muro 128). Use of the hypertonic saline may accelerate the time to visual recovery.
  • Air drying the cornea is helpful in moderate cases. Any activity that helps to evaporate fluid off the cornea will help shorten the time to visual recovery, this may include pointing car vents toward the face or blowing air by the eyes using a hair dryer at arms length.
  • Bandage contact lenses can also be quite helpful in management of painful ruptured bullae (blisters) in more severe disease.


As Fuchs’ dystrophy progresses its medical treatment may fail, at that point surgical management becomes necessary. For many years the only option for patients with visually significant Fuchs’ dystrophy was a full thickness corneal transplant or penetrating keratoplasty (PKP). A corneal transplant involves replacement of the full thickness of the cornea in order to replace the endothelial cells. The cornea is held in place with multiple sutures and some sutures may stay in place for several months to years. Over the past several years there has been a trend to try and treat endothelial dystrophies by transplanting only the posterior, or endothelial, portion (posterior lamella) of the cornea.  Posterior lamellar surgery has been refined over the past several years and now is becoming the standard of care in treatment of early to moderate Fuchs’ endothelial dystrophy.  The most popular surgical procedure is currently named Descemet’s Stripping Endothelial Keratoplasty (DSEK) or Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK).  Please refer to Corneal Transplant and DSEK sections on this website for more details.


Keratoconus is a condition in which the clear front structure of the eye (the cornea) bulges outward like a cone. It is caused by the weakness in the structure of the cornea.

Eye with keratoconus

What Causes Keratoconus?

Tiny fibers of protein in the eye called collagen help hold the cornea in place and keep it from bulging. When these fibers become weak, they cannot hold the shape and the cornea becomes progressively more cone shaped.

Keratoconus appears to run in families. If you have it and have children, it’s a good idea to have their eyes checked for the condition starting at age 10. The condition happens more often in people with certain medical problems, including certain allergic conditions. It’s possible the condition could be related to chronic eye rubbing. Most often, though, there is no eye injury or disease that can explain why the eye starts to change.

Keratoconus usually starts in the teenage years. It can, though, begin in childhood or in people up to about age 30. It’s possible it can occur in people 40 and older, but that is less common.

The changes in the shape of the cornea can happen quickly or may occur over several years. The changes can stop at any time, or they can continue for decades. In most people who have keratoconus, both eyes are eventually affected, although not always to the same extent. It usually develops in one eye first and then later in the other eye.

The earliest signs of keratoconus are usually blurred vision and frequent changes in eye glass prescription, or vision that cannot be corrected with glasses. Symptoms of keratoconus generally begin in late teenage years or early twenties, but can start at any time.

Halos from driving at night with keratoconus

Other symptoms include:

  • Increased light sensitivitylight sensitivity
  • Difficultly driving at night
  • A halo around lights and ghosting (especially at night)
  • Eye strain
  • Headaches and general eye pain
  • Eye irritation, excessive eye rubbing

Treatment Options

  • In the early stages, eyeglasses or soft contact lenses may be used to correct the mild nearsightedness and astigmatism caused in the early stages of keratoconus.
  • Rigid gas permeable (RGP) contact lenses are generally prescribed to correct vision more adequately as the disease progresses. The contact lenses must be carefully fitted, and frequent checkups and lens changes may be needed to achieve and maintain good vision.
  • Intacs, intracorneal rings, are sometimes used to improve contact lens fit.
  • Corneal crosslinking is a new treatment option to halt the progression of keratoconus.
  • A corneal transplant may be needed due to scarring, extreme thinning or contact lens intolerance. This is a surgical procedure that replaces the keratoconus cornea with healthy donor tissue.