Keratoconus

Keratoconus is a thinning of the cornea, the dome-shaped outer layer of eye. Over time, the cornea becomes cone shaped and vision becomes blurry and distorted. Keratoconus is a progressive condition, but treatment can stabilize the eye and prevent the condition from worsening.

Researchers estimate that one in every 2,000 people develop keratoconus. It is more common among Asian populations, particularly people of Indian descent. Between 5 and 15 percent of people with Down syndrome have keratoconus.

The cornea is the clear outer layer of the eye that covers the iris and the pupil. It protects the eye from dust and other particles and the sun’s ultraviolet (UV) rays. The cornea and lens of the eye focus light so that the retina and brain can “see” visual stimuli as images. Keratoconus is one of the most common forms of corneal ectasia, a group of conditions that occur when the cornea becomes thin and misshapen.

Symptoms often appear when a child reaches puberty or their late teens. Because it is a progressive condition, the symptoms start out mild and become more pronounced over time.

Early stage symptoms include:

• Mildly blurred vision
• Distorted vision
• Light sensitivity
• Red, swollen eyes

Later-stage symptoms include:

• More severe blurriness
• Rapidly progressing nearsightedness that requires frequent eyeglass prescription changes
• Inability to wear contact lenses because they no longer conform to the shape of the eye

Researchers do not know for sure what causes keratoconus, though many believe that a combination of genetic and environmental factors contribute to the condition. A child may be born with a predisposition to develop keratoconus.

Because keratoconus makes the cornea thin and delicate, children with the condition should avoid rubbing their eyes. Allergy medicines and avoiding triggers are important preventive strategies for children whose allergies make their eyes itchy.

A clinician will examine the child’s eyes and shape of their corneas. A test called corneal topography measures changes in the cornea’s shape. Another test called pachymetry can measure the thickness of the cornea.

Most cases of keratoconus can be corrected. In mild cases, prescription eyeglasses or contact lenses may be sufficient to improve a child’s vision.

An ophthalmologist may suggest a procedure called corneal cross linking to increase the rigidity of the cornea and prevent the condition from progressing further.

Severe cases of keratoconus require corneal transplant. In this procedure, a surgeon replaces the damaged corneas with healthy ones.

The Department of Ophthalmology at Boston Children's Hospital offers the latest and best in diagnostics and care for children with vision problems, no matter how simple or complex. Children and families come from around the world to our Eye Center for the most advanced vision testing, diagnostics, and treatment available for of all types of visual impairments.