Keratoconus: Causes, Symptoms & Latest Treatment Options

Medically Reviewed

Written by Pooja Rawat, Medical Content Writer

Keratoconus is a progressive eye condition in which the normally rounded cornea (the clear, dome-shaped surface at the front of the eye) bulges outward into a cone shape. Keratoconus often begins when people are in their late teens to early 20s. The cause of keratoconus is largely unknown; however, some studies have found that keratoconus runs in families and that it happens more often in those who have certain medical conditions.

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The main symptoms include worsening vision in one or both eyes, double vision, glare and halos around lights, double or multiple images in one eye, poor vision even after changing glasses, etc. The vision symptoms slowly get worse over a period of about 10 to 20 years.

Early diagnosis is crucial because modern keratoconus treatment (such as glasses, soft toric lenses, RGP lenses, scleral lenses, corneal cross-linking, INTACS/ICRS and corneal transplant) can help improve vision and, when the disease is progressing, slow or stop further corneal weakening.

Quick Overview: Keratoconus

Read the table below to get a better understanding of keratoconus.

What Is Keratoconus? 

Keratoconus is when the cornea thins out and bulges like a cone.

The word “keratoconus” can be broken down:

• Kerato: refers to the cornea.
• Conus: refers to a cone.

The thinning of the cornea and irregularities of the cornea’s surface prevent light from focusing properly on the retina. As a result, vision may become blurry, distorted, or difficult to correct with ordinary spectacles.

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Causes of Keratoconus

No one knows what causes thinning of the cornea and irregularities of the cornea’s surface, although genetic and environmental factors are thought to be involved.

Conditions associated with an increased risk can include:

• A family history of keratoconus
• Allergies, hay fever, or allergic eye disease
• Asthma
• Down syndrome
• Ehlers-Danlos syndrome
• Marfan syndrome
• Certain other inherited or ocular conditions

Keratoconus may also be associated with chronic eye rubbing.

What Are the First Signs of Keratoconus?

A routine change in glasses or contact lens prescription can be a subtle first sign of keratoconus.

Common keratoconus signs and symptoms include:

• Blurred or distorted vision
• Having double vision when looking out of just one eye
• Increasing or irregular astigmatism
• Increasing short-sightedness
• Frequent changes in spectacle prescription
• Increased sensitivity to bright light
• Seeing halos around bright lights
• Trouble seeing clearly at night
• Double or multiple images in one eye
• Poor vision even after changing glasses

How Is Keratoconus Diagnosed?

Asking about your medical and family history and your symptoms will be the first things your eye care provider will begin with. They’ll then conduct a comprehensive eye exam. 

They may also order one or more of the following tests:

• Slit-lamp examination

Allows the eye doctor to examine the cornea under magnification.

• Keratometry

Measures the curvature of the cornea.

• Corneal topography

Creates a map of the corneal surface.

• Corneal tomography

Offers detailed information about both the front and back surfaces and corneal thickness.

• Pachymetry

Measures corneal thickness.

Keratoconus Treatment: What are the Options

The best keratoconus treatment varies and is based on factors such as the severity of the condition, whether it is progressing, the quality of vision, and how well the person tolerates contact lenses.

Treatment generally has 2 goals:

1. Improve vision
2. Prevent further progression.

1. Glasses and contact lenses

In the early stages of the eye condition, you can correct vision with normal eyeglasses or soft contact lenses. As the cornea becomes more irregular, ordinary glasses might no longer offer satisfactory clarity.

Rigid gas-permeable (RGP), hybrid, piggyback, and scleral lenses can give better optical correction in many individuals. Scleral lenses are particularly useful for some people with irregular corneas because they vault over the corneal surface and create a smoother optical surface.

2. Corneal collagen cross-linking (CXL)

Corneal cross-linking uses ultraviolet (UV) light treatment that may slow or stop keratoconus from getting worse. CXL is the principal disease-modifying treatment for progressive keratoconus.

Note: CXL does not simply “cure” keratoconus or immediately restore normal vision, as its primary purpose is to stabilise the cornea.

3. Implantable ring segments (INTACS) for keratoconus

INTACS® are small devices your doctor inserts into your cornea to improve vision or make it easier to fit you with contact lenses. They can help reshape or flatten parts of the cornea and may enhance vision or contact-lens tolerance in selected individuals.

Note: INTACS® does not remove the underlying disease and is not suitable for every patient.

4. Cornea transplant

Your eye specialist may suggest a cornea transplant if you have keratoconus that’s advanced.

Overview of Keratoconus Treatment