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  • A condition that causes the cornea to bulge, causing blurry vision
  • Symptoms include blurry vision, double vision, and sensitivity to light
  • Treatment includes glasses or contacts In severe cases, surgery may be necessary
  • Involves ophthalmology
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Any disease that affects your eyesight can be frightening. Keratoconus, usually diagnosed in the late teens or early adult years, can change the shape of the cornea and distort vision. This means it's important to find the right specialist to treat it.

At Yale Medicine, a cornea specialist will work closely with an optometrist to provide the best possible approach, whether you have a mild case of keratoconus, or you need medically necessary contact lenses or specialty surgery. “Our patients are in the center of the picture and have access to the best surgical options and the best lens options,” says Erica Leigh Volker, OD (doctor of optometry).

What are the symptoms of keratoconus?

Keratoconus is marked by a progressive thinning of the cornea, the transparent dome-shaped front surface of the eye. As the cornea becomes thinner, it bulges outward and develops a cone-like shape. This irregular shape prevents light from being properly focused through the cornea toward the back of the eye.

People with keratoconus notice that their vision becomes blurry, and this symptom rapidly progresses (over a few months), usually beginning in their late teen or early adult years. Other symptoms include double vision and sensitivity to light. In most people with this condition, the vision distortion is worse in one eye than in the other eye.

“Keratoconus may be suspected in someone who requires frequent changes to his or her corrective eyeglass or contact lens prescription or who has glare that is not improved after new glasses,” says Dr. Volker.

How is keratoconus diagnosed?

Keratoconus is not easily diagnosed, especially in its early stages, because the equipment used in a routine eye examination does not always perceive the subtle changes in the corneal thickness or shape.

The best test to diagnose keratoconus is corneal topography, a sophisticated, noninvasive imaging technique that provides a “map” of the curvature of the cornea. Keratoscopy, which measures corneal thickness, can also be used to diagnose the disorder. In very severe cases, the cone shape of the cornea is apparent to the naked eye.

What causes keratoconus?

The cause of keratoconus is not known, but some research suggests that a combination of genetic, environmental (such as asthma or seasonal allergies) and hormonal factors may be involved. “Keratoconus seems to be mostly sporadic,” says Dr. Volker. “It just shows up in someone.”

How is keratoconus treated?

For most people with keratoconus, the visual distortion caused by keratoconus can be treated with prescription eye glasses or contact lenses. In the early stages of the disease, eyeglasses and soft contact lenses can adequately correct vision. As the condition progresses and keratoconus becomes moderate or severe, specialized lenses, such as hard, gas-permeable contact lenses, may be required.

A relatively new and particularly helpful lens is the scleral lens prosthetic device. The scleral lens is made of a rigid material, and it covers more of the eye than traditional lenses, which cover just the cornea. Scleral lenses rest on the sclera, the fibrous protective “white” of the eye that covers the area around the cornea.

“The scleral lens prosthetic devices provide patients with a greater degree of comfort, correction of vision, and quality of life,” says Dr. Volker.

Fitting contact lenses for people with this condition can be a time-consuming task that requires frequent visits because of the irregular shape of the cornea and the progression of disease. With diligence and care, the specialists at Yale Medicine are usually successful in finding the right lens to improve visual acuity.

Although glasses and lenses can usually improve visual distortion caused by keratoconus, they do not treat the underlying illness. For a minority of people with keratoconus who develop severe scarring on their cornea or are unable to tolerate contact lenses, surgery may become necessary. People with keratoconus usually still have to wear corrective contact lenses even after surgery.

What makes Yale Medicine's approach to treating keratoconus unique?

As a specialty center, Yale Medicine has access to emerging diagnostic and therapeutic techniques and devices that benefit its patients. The team-based approach that involves an ophthalmologist working alongside an optometrist also results in better care.