Keratoconus doesn’t cause total blindness on its own, but severe cases can result in significant visual impairment. Corrective lenses, surgical management, and corneal transplants can help.

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Keratoconus is a progressive eye disease characterized by thinning of the cornea, the clear, outermost layer of your eye. It thins and bulges outward into an irregular shape, preventing light from being correctly focused, causing distorted vision.

As the condition progresses, corneal bulging becomes more pronounced, and some people may experience swelling and scarring that further decrease vision.

While visual impairment from keratoconus can meet the criteria for legal blindness, keratoconus isn’t considered a blinding condition on its own. However, it can significantly impair your vision and affect your quality of life.

Keratoconus is a progressive condition that usually appears during early adulthood. It affects both eyes, though it can affect each eye individually and may progress at different rates and with differing severity.

Several different staging systems are used by doctors to determine the progression of keratoconus. It can generally be categorized as mild, moderate, and severe.

Mild

Mild keratoconus presents as blurred or distorted vision and sensitivity to lights or glare. Straight lines may look bent or wavy, and you may experience eye redness or swelling.

During this time, you may notice you’re regularly changing eyeglass prescriptions and having trouble finding corrective lenses that work long-term.

Moderate

Keratoconus generally progresses over a 10 to 20 year period before slowing down. During this time, corneal bulges and irregularities increase, and visual impairment worsens, leading to moderate keratoconus.

Possible symptoms of moderate keratoconus include:

Severe

At its most advanced stages, severe keratoconus can cause tearing and swelling of the cornea, which results in a significant reduction in vision. The swelling can remain for weeks or months while the cornea heals and the tear is replaced by scar tissue.

Learn more about the stages of keratoconus.

Keratoconus does not directly cause complete blindness. Complete blindness is defined as a total loss of light perception.

While keratoconus affects how light is focused through the cornea onto your retina, it doesn’t typically block light from reaching the inner parts of your eye.

Severe visual impairment from advanced stages of the disease may qualify as legal blindness under certain criteria. Keratoconus occurring alongside other eye conditions can increase your chances of experiencing total blindness.

What is “legal blindness?”

The term “legal blindness” describes a specific level of visual impairment that qualifies you for medical benefits and accommodations through government agencies and other organizations.

A person is considered legally blind when their central visual acuity is 20/200 or worse even with the best corrective lenses, or when their visual field is 20 degrees or less in their best-seeing eye.

Visual acuity of 20/200 means if the average person can see something clearly at 200 feet away, the person with visual impairment can only see clearly at a distance of 20 feet.

A visual field of 20 degrees or less means you have very limited peripheral sight and are only able to see slightly beyond what’s central to your vision.

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Monitoring keratoconus progression involves keeping track of your symptoms and having regular screening tests with your eye doctor. Because some signs of progression might not cause noticeable symptoms, visiting your eye doctor for routine checkups is important.

Signs keratoconus is getting worse include:

  • visual distortions and blurriness are getting worse, even with corrective lenses
  • experiencing new visual difficulties in certain settings, like low lighting or at night
  • noticing your corrective lenses are no longer as effective
  • your eye doctor notes new irregularities in the shape of your cornea
  • light sensitivity is worsening
  • contact lenses have become uncomfortable
  • there’s a sudden and significant change in vision
  • corneal clouding, swelling, or scarring are seen in an eye exam

Keratoconus is treatable. Your overall outlook will depend on factors like your age, how early keratoconus was diagnosed, and if you’re living with other eye conditions.

Early intervention can slow or completely stop the progression of keratoconus. However, up to 20% of people may eventually need corneal transplantation to restore visual clarity.

Early interventions include:

  • corrective eyeglasses or soft contact lenses to correct vision
  • rigid gas permeable contact lenses to correct vision and help stabilize the cornea

If keratoconus advances and can’t be managed with early interventions, your doctor may recommend:

  • corneal cross-linking, a minor surgical procedure that strengthens the cornea by increasing collagen links within its layers
  • custom-made or specialized contact lenses

The most advanced stages of keratoconus may require surgical management. Depending on your individual needs, your doctor will consider:

  • intrastromal corneal ring segments (Intacs), small plastic implants that are used to reshape and flatten the cornea
  • corneal transplant, a surgical procedure that replaces that damaged cornea with a donor cornea

Learn more about treatment for keratoconus.

Any vision changes are a reason to speak with your doctor immediately. The sooner you address eye issues, the less likely they are to pose serious risks to your vision.

If you’ve been diagnosed with keratoconus previously, you should contact your doctor about:

  • significant or sudden changes in vision
  • worsening visual clarity
  • increased light sensitivity
  • new visual distortions, like double vision or halos around lights
  • corrective lenses don’t seem to be as effective
  • any eye pain, redness, or swelling

Keratoconus is a progressive eye disease that can affect the clarity of your vision. While it isn’t considered a condition that directly causes complete blindness, it may cause significant visual impairment that qualifies as “legal blindness” in some people.

Early interventions can slow or stop the progression of keratoconus, but some people may require surgical management to restore their vision.