Keratoconus

Keratoconus is a vision disorder that occurs when the normally round cornea (the front part of the eye) becomes thin and irregular (cone) shaped. This abnormal shape prevents the light entering the eye from being focused correctly on the retina and causes distortion of vision.
Keratoconus Illustration

Causes & risk factors

  • Heredity. One in 10 keratoconus sufferers has a close family relative with the disorder.
  • Frequent eye rubbing, especially aggressive “knuckling” eye rubbing.
  • Having a history of asthma, allergies, Ehlos Danlers syndrome, Down’s syndrome, or retinitis pigmentosa.

Symptoms

In its earliest stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. These symptoms usually appear in the late teens or early 20s. Keratoconus may progress for 10-20 years and then slow in its progression. Each eye may be affected differently. As keratoconus progresses, the cornea bulges more and vision may become more distorted. In a small number of cases, the cornea will swell and cause a sudden and significant decrease in vision. The swelling occurs when the strain of the cornea's protruding cone-like shape causes a tiny crack to develop. The swelling may last for weeks or months as the crack heals and is gradually replaced by scar tissue. If this sudden swelling does occur, your doctor can prescribe eyedrops for temporary relief.

Diagnosis

See a doctor of optometry regularly for corneal curvature measurements and tests for irregular astigmatism.

Treatment

Eyeglasses or soft contact lenses may be used to correct the mild nearsightedness and astigmatism that is caused by the early stages for keratoconus. Corneal cross-linking surgery is indicated early after diagnosis to stabilize the structure of the cornea and slow progression. As the disorder progresses and cornea continues to thin and change shape, rigid gas permeable contact lenses can be prescribed to correct vision adequately. In most cases, this is adequate. The contact lenses must be carefully fitted, and frequent checkups and lens changes may be needed to achieve and maintain good vision. In a few cases, a corneal transplant is necessary. However, even after a corneal transplant, eyeglasses or contact lenses are often still needed to correct vision.

Corneal cross-linking surgery halts or slows progression and is indicated early after diagnosis, or if later in the course of the disease there is still an increase in the glasses prescription. Intacs intracorneal removable inserts can stretch the cornea to stabilize astigmatism and near-sighted refractive errors. Once the progression has stabilized from life or cross-linking, an implantable Collamer lens surgery can correct higher prescriptions so that glasses or conventional soft contact lenses can be utilized.

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