Learn what causes keratoconus, how to identify symptoms like blurry vision, and explore treatment options from specialized lenses to advanced corneal surgery.

What is Keratoconus? Causes and Care

Keratoconus is an eye condition where the cornea, the sensitive organ at the front of the eye, becomes thinner and conical in shape. It can result in blurry, double, or other unusual vision. Its onset is gradual, and it may first present much like other conditions, such as astigmatism. Untreated, it can lead to permanent vision loss. Various treatment options, from corrective lenses to surgery, may be prescribed, depending on the progression and severity of symptoms.

Understanding Keratoconus: When the Cornea Changes Shape

How the Cornea Should Function vs. Keratoconus

According to the American Academy of Ophthalmology (AAO), the dome-shaped cornea normally focuses light onto the retina. With the change to a conical shape, less light is focused, leading to blurry, distorted vision. This can affect a person’s ability to read, drive, and perform other day-to-day activities.

Why the “Cone” Shape Occurs: Thinning and Bulging

Keratoconus occurs due to malformations in a protein called collagen, which gives the cornea its shape. The cone is produced when the collagen thins out and bulges.

Is Keratoconus a Rare Condition?

Keratoconus is thought to affect roughly one in every 2,000 people. Its prevalence may be higher in certain racial or ethnic groups.

What Causes Keratoconus? Identifying the Risk Factors

The causes of keratoconus are unclear, but there are genetic, environmental, and hormonal risk factors. It can also correlate with certain conditions that affect much more than the eyes.

Genetics and Family History: The Hereditary Link

About one in ten people with keratoconus have a family history of the condition. The precise genetic cause has, however, not yet been determined.

The Impact of Chronic Eye Rubbing on Corneal Stability

Chronic eye rubbing puts pressure on the delicate cornea, which can cause it to lose its proper shape over time and contribute to the development of keratoconus. The American Academy of Ophthalmology (AAO) recommends that people with itchy eyes talk to their eye doctor about medication to help control it.

Environmental Triggers: Allergies, Asthma, and Eczema

Keratoconus may be associated with environmental factors such as allergies, asthma, and eczema. According to a 2025 study in Translational Vision Science and Technology, allergies contribute to keratoconus by inducing ocular inflammation.

Connective Tissue Disorders and Systemic Links

Keratoconus also has correlations with systemic conditions, especially connective tissue disorders like Marfan syndrome and Ehlers-Danlos syndrome, but also with atopy and Down syndrome. The reasons for these correlations are still unclear. Interestingly, a 2023 study in Life, an international journal, suggests that diabetes may inhibit the development of keratoconus.

Recognizing the Symptoms: Is Your Vision Changing?

Early Signs: Mild Blurring and Light Sensitivity

The symptoms of keratoconus typically begin in adolescence, and the disease is usually diagnosed in the twenties or thirties. Generally, both eyes are affected, but often to very different degrees. Early symptoms are usually mild and start with some blurring of the visual field and increased sensitivity to light. These relatively nonspecific symptoms can lead to an initial diagnosis with other conditions, such as astigmatism.

Progression Indicators: Ghosting, Halos, and Increased Glare

More advanced keratoconus can cause ghosting, in which a person perceives multiple images of the same object, often in the same eye. Especially at night, the individual can also perceive halos or rings around lights and experience increased glare. This particularly affects certain activities such as nighttime driving.

Frequent Prescription Changes and Sudden Vision Loss

As the cornea becomes more conical over time, the way light enters the eye changes. This can lead to drastic adjustments to eyeglass or lens prescriptions being necessary over relatively short periods of time.

Why Keratoconus is Often Misdiagnosed as Simple Astigmatism

Keratoconus and astigmatism are both conditions in which the cornea changes shape. They have similar symptoms, including blurred or distorted vision and frequent prescription changes. Since keratoconus is much less common and progresses to a cone shape more gradually, it is often initially diagnosed and treated as astigmatism.

Professional Diagnosis and Monitoring

What to Expect During a Keratoconus Eye Exam

Depending on the progression of the disease, a regular eye exam can detect keratoconus. The more regularly your eyes are checked, the earlier keratoconus can be detected, and the more vision can be preserved with treatment. To check for keratoconus, your ophthalmologist will scan the cornea to detect curvature and map its surface.

Understanding Corneal Topography and Mapping

Corneal topography is a procedure in which an ophthalmologist measures irregularities in the curvature of the cornea by scanning its surface. In addition to detecting potential astigmatism or keratoconus, this mapping is also used to detect curvature changes caused by eye injuries. During the scan, the patient faces a bowl with chin and head rests and looks at a target within the bowl. This involves no physical manipulation of the eye.

The Importance of Measuring Corneal Thickness (Pachymetry)

Since keratoconus involves the cornea thinning as it changes shape, measuring corneal thickness (Pachymetry) can offer a clue to the disease’s progression. It is also used to assess the efficacy of treatments such as cross-linking.

Modern Keratoconus Treatment Options

Corrective Lenses: From Standard Glasses to Scleral Lenses

Early on, typical eyeglasses are often enough to correct vision problems caused by keratoconus. As the condition progresses, ophthalmologists may recommend contact lenses to provide better correction. Hard contacts (scleral lenses) are often used by patients with corneal irregularities, which the hard lenses compensate for by focusing more light into the eye.

Corneal Cross-linking

A relatively new treatment option for advanced keratoconus, corneal cross-linking (CXL) involves repairing the malformed collagen protein in the cornea by cross-linking new fibers. This is accomplished with the use of Vitamin B (riboflavin) and ultraviolet light. A bandage is placed over the eye and kept there for a week to allow the cornea to heal. The objective is to halt disease progression, unlike a corneal transplant. CXL is an outpatient procedure and may not be covered by vision insurance.

Keratoconus Surgery: When is a Transplant Necessary?

Corneal transplant surgery may be recommended for patients with severe keratoconus. This is usually because there is extensive damage to one or more layers of the cornea, and they need to be replaced with donor cornea tissue to restore sight.

Understanding Keratoplasty: Full vs. Partial Thickness Transplants

Corneal transplants differ in whether they replace the entire cornea or only some of its layers. A full-thickness transplant involves replacing the whole cornea and has a higher risk of rejection. Partial-thickness transplants, more common in keratoconus treatment, replace only the outer and middle layers and have a lower chance of rejection. Your ophthalmologist will discuss which transplant type they recommend and why.

Success Rates and Recovery Expectations for Corneal Surgery

According to the AAO, it can take a year or more to completely recover after a full-thickness transplant. Thirty percent of full-thickness transplants are ultimately rejected by the body’s immune system, though immediately treating it with steroids can inhibit the rejection response. Partial-thickness transplants can have a lower risk of rejection, while repeated transplants have a higher risk.

Life After Surgery: Will You Still Need Corrective Lenses?

According to the National Keratoconus Foundation, it is not uncommon for patients to require corrective lenses after transplant surgery. This is because, unlike corneal cross-linking, transplants do not halt the disease’s progression. The new cornea may itself develop keratoconus, astigmatism, or other conditions. Also, patients with additional diseases that involve other parts of the eye, such as macular degeneration or glaucoma, will still suffer vision loss from these conditions unless and until they are properly treated. Early detection and treatment lead to the best outcomes. Get regular eye exams and tell your eye doctor about any changes in your vision.