Part 1 | Keratoconus: When the Cornea Changes Shape and Vision Becomes Distorted

Keratoconus is an eye condition that affects the cornea, the clear front window of the eye. In a healthy eye, the cornea has a smooth, dome-like shape. With keratoconus, the cornea gradually becomes thinner and steeper, causing it to bulge forward into a cone-like shape. This change can distort how light enters the eye, leading to blurry, shadowed, or irregular vision.

Keratoconus often starts in the teenage years or early adulthood, but it can be diagnosed at different ages. In many patients, it progresses slowly over time. Because the cornea changes shape, patients may notice that their glasses prescription keeps changing or that regular glasses no longer provide clear vision.

A doctor and patient sit by a corneal topography machine, discussing keratoconus. Diagrams and text about eye care are in the background.

Common Symptoms of Keratoconus

Keratoconus symptoms can vary from mild to more advanced. Some patients may not realize they have it at first, especially if only one eye is affected more than the other.

Common symptoms include:

• Blurry vision

• Distorted or “warped” vision

• Frequent changes in glasses prescription

• Increased nearsightedness or astigmatism

• Glare or halos around lights

• Difficulty driving at night

• Eye strain or headaches from poor visual clarity

• Vision that does not seem fully corrected with glasses

As keratoconus progresses, glasses may become less effective because the cornea is no longer a smooth, regular shape. Mayo Clinic notes that keratoconus can cause blurred vision, light sensitivity, and glare as the cornea thins and bulges forward.

What Causes Keratoconus?

The exact cause of keratoconus is not always known. It may involve a combination of genetics, corneal structure, environmental factors, and eye rubbing. Some patients have a family history of keratoconus, while others do not.

One important risk factor is chronic eye rubbing. Patients with allergies, itchy eyes, or irritation may rub their eyes frequently, which can make keratoconus worse or contribute to progression. Cleveland Clinic notes that people with keratoconus often rub their eyes a lot, and this may cause the condition to develop more rapidly.

Because of this, managing allergies, dryness, and eye irritation is an important part of care.

How Eye Doctors Check for Keratoconus

A routine eye exam can raise suspicion for keratoconus, especially when a patient has increasing astigmatism or vision that does not correct well with glasses. However, keratoconus is best evaluated with special testing.

Corneal Topography or Tomography

One of the most important tests for keratoconus is corneal topography or corneal tomography. These tests create a detailed map of the cornea’s shape and curvature. They can detect steepening, thinning, and irregular patterns that may not be obvious during a basic eye exam.

Refraction

A refraction measures the glasses prescription. In keratoconus, the prescription may change frequently, especially the astigmatism.

Slit Lamp Exam

The eye doctor examines the cornea under a microscope to look for thinning, scarring, or other changes.

Corneal Thickness Testing

Because keratoconus causes corneal thinning, measuring corneal thickness can help determine severity and monitor changes over time.

Why Early Diagnosis Matters

Early diagnosis is important because keratoconus can progress. Once the cornea becomes very irregular or scarred, vision correction becomes more difficult.

The goal is to identify keratoconus early, monitor for progression, and decide whether treatment is needed to help stabilize the cornea. Many patients can maintain useful vision with glasses or specialty contact lenses, especially when the condition is detected and managed early.

Treatment Options for Keratoconus

Treatment depends on how advanced the keratoconus is and whether it is progressing.

Glasses

In mild cases, glasses may still provide good vision. However, as the cornea becomes more irregular, glasses may not fully correct the distortion.

Soft Contact Lenses

Some mild cases can be managed with soft contact lenses, including toric lenses for astigmatism. If vision remains distorted, specialty lenses may be needed.

Rigid Gas Permeable Lenses

Rigid gas permeable lenses can provide sharper vision by creating a smooth optical surface over the irregular cornea. These lenses may be helpful when glasses or soft contacts are no longer enough.

Hybrid Contact Lenses

Hybrid lenses have a rigid center with a soft outer skirt. They may offer sharper vision than soft contacts with improved comfort compared to some traditional rigid lenses.

Scleral Contact Lenses

Scleral lenses are often an excellent option for keratoconus. These larger specialty lenses vault over the cornea and rest on the white part of the eye. The space between the lens and cornea is filled with fluid, creating a smoother surface for light to pass through.

Scleral lenses can often provide clearer, more stable vision for patients with moderate or advanced keratoconus. Johns Hopkins lists scleral lenses as one of the treatment options used for keratoconus.

Corneal Cross-Linking

Corneal cross-linking is a treatment designed to help slow or stop progression of keratoconus. It does not replace glasses or contact lenses, but it can help strengthen the cornea and reduce the risk of worsening.

During cross-linking, riboflavin eye drops and ultraviolet light are used to strengthen collagen bonds in the cornea. Johns Hopkins describes corneal collagen cross-linking as a minimally invasive therapy that helps stiffen the cornea and slow or stop corneal deformation.

For many years, the main FDA-approved approach in the United States involved removing the corneal surface layer, called the epithelium, before treatment. In 2025, the FDA approved Epioxa, an “epi-on” cross-linking therapy that does not require removal of the corneal epithelium, expanding treatment options for progressive keratoconus.

Patients who may need cross-linking are usually referred to a corneal specialist.

Corneal Transplant

In advanced keratoconus, especially when there is significant corneal scarring or the cornea becomes too irregular for contact lenses, a corneal transplant may be considered. This is typically reserved for more severe cases when other options are no longer successful.

Even after a corneal transplant, many patients still need glasses or contact lenses to achieve their clearest vision. Johns Hopkins notes that glasses or contact lenses are usually still needed after transplant surgery to provide the clearest vision.

Avoid Eye Rubbing

One of the most important lifestyle recommendations for keratoconus patients is: do not rub your eyes.

Eye rubbing can place mechanical stress on the cornea. If your eyes itch, burn, or feel irritated, your eye doctor may recommend allergy drops, dry eye treatment, lid hygiene, or other options to reduce the urge to rub.

This is especially important for children, teenagers, and young adults with allergies or frequent eye irritation.

When Should You Get Checked?

You should schedule an eye exam if you notice:

• Blurry or distorted vision

• Frequent glasses prescription changes

• Increasing astigmatism

• Glare or halos at night

• Trouble getting clear vision even with new glasses

• A family history of keratoconus

• Frequent eye rubbing or severe allergies

Keratoconus is easier to manage when it is found early. A comprehensive eye exam with corneal imaging can help determine whether the cornea is healthy, stable, or showing signs of progression.

Final Thoughts

Keratoconus is a condition where the cornea becomes thinner and more cone-shaped, causing blurry or distorted vision. Some patients do well with glasses or soft contacts early on, while others need specialty contact lenses such as rigid, hybrid, or scleral lenses.

For patients whose keratoconus is progressing, corneal cross-linking may help strengthen the cornea and reduce the risk of worsening. The key is early diagnosis, regular monitoring, and choosing the right treatment plan based on the patient’s corneal shape, vision needs, and disease progression.

At OPT-ISM, we can evaluate vision changes, check for irregular astigmatism, and help determine whether additional corneal testing or referral to a corneal specialist is needed.