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AFBAmerican Foundation®
for the Blind

Expanding possibilities for people with vision loss

Keratoconus

By Mrinali Patel, M.D.

What Is Keratoconus?

Keratoconus is a bilateral (both eyes) degenerative condition of the cornea, a transparent dome-shaped tissue that forms the front part of the eye. Keratoconus gradually causes the cornea to thin, bulge/protrude outward, and become cone-shaped. This creates an abnormal curvature of the eye called astigmatism that can cause blurry vision, glare, or light sensitivity (photophobia).

People with keratoconus typically begin to exhibit symptoms in their teens, and the disease gradually progresses over time. In the later stages, scarring can develop in the area of the corneal bulge or protrusion, which can further impede vision.

Occasionally, people with keratoconus can develop hydrops, which is a sudden break in the internal surface of the cornea that allows fluid to enter the cornea and cause it to swell. This can cause pain and a sudden decrease in vision.

What Causes Keratoconus?

The cause of keratoconus is unknown. While most people with keratoconus are otherwise healthy, patients with Down syndrome, connective tissue diseases, and certain retinal conditions are at higher risk of developing keratoconus.

How Is Keratoconus Diagnosed?

Keratoconus is diagnosed by an ophthalmologist or corneal specialist by clinical examination and additional tests such as topography, an imaging study that maps out the curvature of the corneas.

How Is Keratoconus Treated?

  • Glasses or contact lenses: In the earliest stages of keratoconus, people may require glasses or contact lenses to correct the astigmatism. As the disease progresses, patient may require hard or rigid gas permeable contact lenses. These lenses serve to create a smooth surface over the irregular-shaped cornea.
  • Specialized contact lenses: If the person cannot tolerate hard or rigid gas permeable lenses, more specialized lenses, such as hybrid lenses containing a soft and hard contact lens component, or scleral lenses may be required. Scleral lenses are larger-diameter gas permeable contact lenses that are designed to cover the entire corneal surface and rest on the sclera, which is the white part of the eye.
  • Corneal implants: Corneal implants called intracorneal ring segments can be surgically inserted in some patients to change the shape of the cornea to improve vision.
  • Corneal transplantation: If keratoconus is very advanced or there is significant scarring blocking vision, patients may also undergo corneal transplantation, in which the cornea or part of the cornea is surgically removed and replaced with donor cornea
  • Collagen cross-linking: There are studies underway examining collagen cross-linking, a method of applying riboflavin drops and applying ultraviolet light to the cornea to create cross-linking between the collagen fibers of the cornea. The goal of this treatment is to strengthen the cornea in people with keratoconus.
  • Treatment for hydrops: In addition, people with keratoconus who develop hydrops can be treated with steroid or sodium chloride drops to attempt to decrease swelling of the cornea. Hydrops typically resolves over the course of several weeks.

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