Keratoconus - Symptoms, Causes, Diagnosis & Treatment

8 sources cited
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What is Keratoconus?

Keratoconus is a rare, progressive eye disorder that occurs when collagen protein fibers in the eye become weak and thin. It results in a cone-shaped or bulging cornea (transparent, dome-shaped layer on the front of the eye) and causes distorted vision. 

The cornea is responsible for focusing light that enters your eye. It’s supported by a layer of collagen fibers that hold the cornea in place and give it shape. When collagen fibers weaken, the cornea loses its shape. The ability to focus light diminishes, causing vision loss.


What are the Symptoms of Keratoconus?

Keratoconus progresses over many years, and symptoms typically start in puberty and stabilize over time. Keratoconus may affect each eye differently. 

Keratoconus symptoms can vary from person to person. The most common signs and symptoms include:

In severe keratoconus cases, swelling can crack the cornea, leading to scar tissue, pain, and redness. 

Keratoconus Risks and Complications 

If left untreated, keratoconus can lead to permanent vision loss. LASIK eye surgery is also not recommended for people with keratoconus because it can worsen the condition.

What Causes Keratoconus?

Experts believe genetic and environmental factors are responsible for developing keratoconus. However, the exact cause of keratoconus is unknown.

Keratoconus is rare and occurs in about 1 in 1,000 people. It affects all races and usually occurs in both eyes.6 

Risk Factors for Keratoconus

Keratoconus has been linked with family history, but genetic patterns are not predictable. People with Down’s syndrome and Ehlers Danlos (connective tissue disorder) have a higher risk of developing keratoconus. 

Environmental risk factors of keratoconus include:

  • Repeated eye rubbing
  • Allergies and asthma
  • Eczema
  • Sleep apnea
  • Retinitis pigmentosa (genetic disease affecting the retina)
  • Floppy eyelid syndrome (loss of eyelid elasticity)

Can You Prevent Keratoconus? 

You cannot prevent keratoconus, but effectively treating and managing allergies and asthma can reduce eye rubbing, reducing the risk of developing keratoconus.  

Avoiding eye rubbing is also essential to minimize disease progression.

How is Keratoconus Diagnosed?

A comprehensive eye exam by a licensed ophthalmologist is used to diagnose keratoconus. 

During the examination, the eye doctor will:

  • Look at the external appearance of the eye for a cone-shaped cornea
  • Test visual acuity (clarity of distance vision)
  • Use a slit-lamp (microscope) to look for corneal thinning 
  • Utilize corneal topography (imaging study to look at the health of the cornea)

Keratoconus Treatment (By Stage)

The treatment plan for keratoconus will depend on the stage, severity, and how fast the condition progresses. 

The treatment goals are to improve vision and slow the progression of the disease. Keratoconus can’t be cured or reversed.

Mild and Moderate Keratoconus

Early keratoconus with mild symptoms are treated with eye glasses and contact lenses, including:

  • Soft contact lenses. These lenses can easily correct for slight blurring and distorted vision. 
  • Gas permeable contact lenses. These are hard lenses used to correct irregular astigmatism and improve vision.
  • Piggyback lenses. These consist of a hard lens on top of a soft lens. Used when a hard lens is not tolerated.
  • Hybrid lenses. These lenses have a hard middle and soft edges for comfort and for those who can’t tolerate hard lenses.
  • Scleral lenses. These are used for irregularly shaped corneas. The lens rests on the sclera (white part of the eye) instead of directly on top of the cornea. 

Intermediate and Advanced Keratoconus 

Surgical and therapeutic treatments are available for people with advanced or progressing keratoconus when eyeglasses and contact lenses are no longer effective at correcting vision. They include:

  • Corneal collagen cross-linking treatment combines ultraviolet light and vitamin-infused eye drops to strengthen collagen fibers in the cornea. 
  • Corneal ring (Intacs). A surgical procedure that inserts plastic rings in the middle of the cornea to correct its shape and improve vision.
  • Corneal transplant (keratoplasty). Another surgical procedure that removes the cornea and replaces it with donor corneal tissue. It’s used when there is extreme thinning or corneal scarring. 


Keratoconus is a rare eye condition that occurs when the collagen fibers in the cornea (transparent, dome-shaped layer on the front of the eye) thin and weaken. It causes the cornea to bulge and develop a cone shape, leading to distorted vision.  

Keratoconus is a rare disorder that typically starts during puberty. It progresses over several years and is linked to genetics and environmental factors. Symptoms include blurred vision, sensitivity to light, and poor night vision. Repeated eye rubbing can make keratoconus worse.

While keratoconus can’t be cured, several treatments can help slow progression and improve vision. These treatments include eyeglasses, hard and soft contact lenses, corneal cross-linking, and corneal transplant. 

8 Cited Research Articles
  1. Keratoconus.” American Optometric Association.
  2. Meek K. “Corneal collagen: its role in maintaining corneal shape and transparency.” Biophys Rev, Ltd, 6 June 2009. 
  3. Keratoconus.” National Organization for Rare Disorders (NORD).
  4. What is regular vs. irregular astigmatism?” AcuFocus
  5. Keratoconus.” Cleveland Clinic
  6. Hashemi H., Haydarian S., Hooshmand E., Saatchi M., Yekta A., Aghamirsalim M. et al. “The Prevalence and Risk Factors for Keratoconus: A Systematic Review and Meta-Analysis.” Cornea, Ltd, Feb. 2020. 
  7. Keratoconus.” American Academy of Ophthalmology.
  8. Corneal ring implantation and keratoconus.” Precision Keratoconus Center.
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