Keratoconus

Keratoconus (KEHR-uh-toh-KOH-nus) is a very rare eye condition in which the normally round, dome-like cornea becomes thin and develops a cone-like bulge.  Keratoconus literally means “cone-shaped cornea.”  As light enters the cone shaped cornea it is bent and distorted and unable to come to a point of clear focus on the light-sensitive retina, causing blurred vision.  Keratoconus can make some activities difficult, such as driving, typing on a computer, watching television or reading.  This condition is typically not associated with redness, inflammation or other "acute" symptoms and therefore may go undetected for a long period of time.  Keratoconus is often specifically studied by ophthalmologists specializing in the cornea. 

Keratoconus usually affects both eyes but the two eyes often progress at different rates.  This disease typically begins during teenage years.  In most patients, it progresses for several years before stabilizing in the third to fourth decade of life.  In severe cases it can continue to worsen.  In these cases the cornea continues to thin and bulge outward, further blurring vision.  Scarring of the cornea can also develop.

Symptoms:

• blurred vision
• distortion of vision
• sensitivity to light
• glare
• slight irritation
• the need for frequent prescription changes

On occasion, if progression is rapid and keratoconus moves into the advanced stage, patients can develop hydrops, a clouding of vision in one eye.  Hydrops is caused by a sudden infusion of fluid into the stretched cornea, making the cornea appear swollen and opaque.  It is a rare complication that gradually clears over several weeks or months, although in severe cases, the central part of the corneal bulge can form superficial scarring and further impair vision.

Who is at risk:

Researchers believe that approximately 3 million people worldwide have keratoconus.  It affects males and females of all races throughout the world.  The causes are still being researched, but the likelihood of developing keratoconus is greater if you have:

• a relative with keratoconus
• had excessive laser eye surgery
• hay fever, eczema, asthma or food allergies

Treatment

The treatment approach to keratoconus follows an orderly progression from glasses to contact lenses to corneal transplantation.  Glasses are an effective means of correcting mild keratoconus.  As the cornea steepens and becomes more irregular glasses are no longer capable of providing adequate visual improvement.  Contact lenses are the next approach to treatment.

Rigid gas permeable (RGP) contact lenses

These are the primary treatment for keratoconus.  To counteract the distortion of the cornea, most keratoconus patients require special RGP lenses to provide a smooth surface that can focus light in place of their own cornea’s distorted surface.  Because the pattern of distortion in keratoconus is as unique as a fingerprint, the RGP lenses are custom prescribed and manufactured.

A proper contact lens fitting is crucial to ensure optimal vision, comfort, and eye health.  Poor fitting lenses can lead to corneal abrasions, scarring, and infection.  At the Cornea and Laser and Vision Institute, we are proud to have Dr. Judy Miles, who specializes in fitting the most difficult cases for contact lenses and saves many patients from needing surgery.

Surgery

Many keratoconus patients will never require surgery, but it is an option in severe and advanced cases.  If our cornea specialists determine you have significant scarring of the cornea, he may recommend corneal transplant surgery.  In this procedure, the scarred tissue is replaced with a section of donated cornea.  About 10 to 20% of keratoconus patients will eventually require a corneal transplantation.  However, corneal transplantation is not a cure.  Following a successful corneal transplant, most patients still need glasses, soft contacts, or RGP lenses for adequate vision.

A new procedure is now available that the doctors at the Cornea and Laser Vision Institute are performing for keratoconus.  This procedure uses topical drops and a special wavelength of light to strengthen the cornea and help keratoconus patients improve their vision without the need for invasive surgery.  For more information visit www.cxlusa.com or call (314) 966-5000 and ask about corneal collagen crosslinking, also known as CXL.

Precautions

Patients with keratoconus must not have LASIK or PRK laser eye surgery due to an unacceptable risk of a poor outcome.  The cornea in keratoconus is unusually thin and weak.  For patients with keratoconus, LASIK surgery thins and weakens their corneas further.  This can irreversibly destabilize the cornea and accelerate its distortion.  Rubbing the eyes may also increase the progression of keratoconus.  Eye rubbing can often be very vigorous with patients using excessive force with their knuckles.  Corneas already weakened by inflammation may develop thinning and protrusion as a result of rubbing.

Normal Cornea	Mild Keratoconus	Advanced Keratoconus