Keratoconus

Keratoconus is a progressive disorder that affects the cornea—the outermost layer of the eye. The middle of the cornea gradually thins and bulges outward, forming a rounded cone shape. These structural changes result in vision problems. In most cases, both eyes are affected.

Prevalence

Keratoconus affects about one in every 2,000 Americans. It is more prevalent among teenagers and adults in their 20s, but it can affect individuals as young as nine years old.

Signs and Symptoms

The abnormal curvature of the cornea affects the patient’s ability to see (refractive power). In most cases, the cornea will stabilize after a few years without ever causing severe vision problems. However, if left untreated, keratoconus can result in progressive vision loss. Common signs and symptoms include:

  • Moderate-to-severe distortion (from astigmatism)
  • Blurred vision (from nearsightedness)
  • Swelling
  • Development of scar tissue that impairs vision

Causes

Research suggests that keratoconus stems from one of several possible causes:

  • Family history: About seven percent of those with keratoconus have a family history of the condition.
  • Eye injury: Damage to the cornea may increase the risk of developing keratoconus. Excessively rubbing the eyes or wearing hard contact lenses for many years may injure the cornea.
  • Certain eye diseases: Keratoconus is associated with certain eye diseases, including retinitis pigmentosa, retinopathy of prematurity, and vernal keratoconjunctivitis.
  • Other conditions: Keratoconus has been linked to other diseases, such as Leber's congenital amaurosis, Ehlers-Danlos syndrome, Down syndrome, and osteogenesis imperfecta.

Treatment

Treatment for keratoconus will depend on your symptoms. Initially, when symptoms are mild, you can correct your vision with eyeglasses. Later, you may need to wear specially fitted contact lenses to help keep your vision in proper focus.

Other treatment options include:

Corneal Intacs: The U.S. Food and Drug Administration has approved Intacs for the treatment of mild-to-moderate keratoconus. This small, curved device is surgically inserted into the cornea to help reshape the cornea and improve vision. The surgery is generally performed as an in-office procedure. Healing time is gradual, often taking three months to obtain the best vision. Complications with Intacs are rare, but may include under-correction, over-correction, induced astigmatism, infection, glare, halos, and extrusion of the insert. Minimal scarring may also occur in the area of the rings.

Corneal Cross-Linking: This minimally invasive, in-office procedure is the only treatment that can slow or stop the progression of keratoconus. During this FDA-approved procedure, riboflavin eye drops are placed in the eyes and activated by ultraviolet light.

Corneal Transplantation: In severe cases, your ophthalmologist may recommend a corneal transplant. This surgery is successful in more than 90 percent of those with advanced keratoconus. Several studies have also reported that 80 percent or more of these patients have 20/40 vision or better after the operation.