Keratoconus: Causes, Symptoms & Treatment

Keratoconus is a progressive eye condition in which the cornea — the clear front surface of the eye — gradually thins and bulges into an irregular, cone-like shape. Because the cornea no longer focuses light evenly onto the retina, vision becomes increasingly blurred and distorted. The name comes from the Greek kerato (cornea) and konos (cone), which describes exactly what happens to the eye's surface over time.

Keratoconus was historically estimated to affect around 1 in 2,000 people, but research using modern corneal imaging suggests it is more common than once thought. It typically appears in the teens or twenties, often affects both eyes (though rarely to the same degree), and can progress at different rates from person to person. Early diagnosis and the right management make a meaningful difference to long-term vision.

Key Takeaways

Keratoconus is a progressive condition that changes the shape of the cornea and distorts vision.
The exact cause is unknown, but genetics and eye rubbing are well-recognised contributing factors.
It is usually diagnosed with corneal topography, which can detect changes before vision is badly affected.
Treatment depends on severity, ranging from glasses and soft lenses to specialty rigid lenses, cross-linking, and (in advanced cases) surgery.
Specialty contact lenses allow most people to achieve clear, comfortable vision without surgery.

What is Keratoconus?

Keratoconus is a condition where the normally round, dome-shaped cornea thins and steepens into a cone. This irregular surface scatters light as it enters the eye, so instead of focusing to a single sharp point on the retina, the image becomes blurred and ghosted. The change is caused by a gradual weakening and thinning of corneal tissue, a process known as ectasia.

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Symptoms of Keratoconus

The earliest signs of keratoconus often look like ordinary short-sightedness or astigmatism, which is why it can be overlooked without the right examination. As the cornea becomes more irregular, common symptoms include:

Blurred or distorted vision, with straight lines sometimes appearing wavy
Ghosting, streaking, or double vision in one eye
Increased sensitivity to light and glare, and haloes around lights at night
Frequent changes in spectacle prescription that never quite give clear vision
A sudden worsening or clouding of vision in more advanced cases

Because the early picture can resemble a simple refractive error, keratoconus is best confirmed with corneal imaging rather than a standard sight test alone.

Causes and Risk Factors

The precise cause of keratoconus is still not fully understood, but it is thought to result from a combination of genetic and environmental factors. Recognised risk factors include:

Genetics and family history: A family history of keratoconus raises the risk, pointing to an inherited weakness in the collagen fibres that give the cornea its strength.
Vigorous eye rubbing: Frequent, forceful rubbing — often linked to itchy eyes from allergies, hay fever, eczema, or asthma — can stress the cornea and is associated with faster progression. Avoiding eye rubbing is one of the few things patients can actively control.
Associated conditions: Keratoconus has been linked with conditions such as Down syndrome, Ehlers-Danlos syndrome, and atopic disease.

How Keratoconus Is Diagnosed

Keratoconus is diagnosed through a detailed eye examination, and early or mild cases are best detected with corneal topography. A corneal topographer measures the precise shape of the cornea and generates a 3D map of its surface, revealing subtle steepening or irregularity long before it would show up on a standard eye test. This is why a comprehensive eye examination is so important when keratoconus is suspected — particularly for younger patients or anyone with a family history. Catching the condition early opens the door to treatments that can help stabilise it before significant vision is lost.

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Correcting Early Keratoconus: Glasses and Soft Lenses

In the early stages, when corneal distortion is still mild, vision can often be corrected with non-invasive options.

Spectacles

Glasses can improve functional vision in mild keratoconus and are easy to update as the prescription changes. As the cornea becomes more irregular, however, glasses become less effective and some blurring or ghosting usually remains.

Soft Contact Lenses

Soft lenses sit on the cornea and can give clearer, more stable vision than glasses in mild to moderate cases. In more advanced keratoconus, where the corneal shape is highly irregular, standard soft lenses may no longer provide a good fit, and specialty lenses become necessary.

Specialty Contact Lenses for Keratoconus

For moderate to advanced keratoconus, specialty rigid lenses are usually the most effective way to achieve clear vision, because they create a smooth optical surface that compensates for the cornea's irregular shape. Fitting these lenses well takes time, the right equipment, and experience, which is why they are best handled through dedicated specialty contact lens services.

Rigid Gas-Permeable (RGP) Lenses

Firm, oxygen-permeable lenses that sit on the cornea and hold their shape, masking corneal irregularity to give sharp vision. They are durable but may take time to adapt to.

Piggyback Lenses

A soft lens worn underneath an RGP lens on the same eye, combining the clarity of a rigid lens with added comfort and protection for the corneal surface.

Hybrid Lenses

A rigid centre surrounded by a soft outer skirt, pairing the sharp vision of RGP lenses with greater comfort and stability. They require specialised fitting.

Scleral and Mini-Scleral Lenses

Large-diameter rigid lenses that vault over the cornea and rest on the white of the eye, trapping a reservoir of fluid against the corneal surface. They are particularly comfortable for highly irregular corneas and are a popular choice for advanced keratoconus. For many patients, well-fitted scleral lenses can delay or reduce the need for more invasive treatment.

Corneal Collagen Cross-Linking (CXL)

Corneal collagen cross-linking is a procedure designed to slow or halt the progression of keratoconus. Riboflavin (vitamin B2) drops are applied to the cornea, which is then exposed to controlled ultraviolet light, strengthening the collagen bonds and stiffening the corneal tissue. CXL aims to stabilise the cornea and can help many patients avoid the need for a corneal transplant later in life. It does not usually restore clear vision on its own, so most patients still wear glasses or specialty lenses afterwards. CXL is performed by ophthalmologists.

Surgical Options for Keratoconus

When the cornea becomes too irregular, thin, or scarred for lenses to be effective, surgical options carried out by ophthalmologists may be considered.

Intrastromal Corneal Ring Segments (Intacs)

Small, clear, semi-circular implants placed within the cornea to flatten and reshape its surface. They can reduce irregularity, improve vision, and make lens wear easier, and the procedure is less invasive than a transplant.

Corneal Transplant (Keratoplasty)

Replacement of damaged corneal tissue with healthy donor tissue. Penetrating keratoplasty (PK) replaces the full thickness of the cornea, while deep anterior lamellar keratoplasty (DALK) preserves the innermost layer and carries a lower risk of rejection. A successful transplant can significantly improve vision, though recovery takes time and ongoing follow-up is essential.

How EMME Visioncare Supports Keratoconus Patients

At EMME Visioncare, we focus on the non-surgical management of keratoconus. We do not perform surgical procedures such as cross-linking or transplants; instead, our optometrists concentrate on careful monitoring and on fitting specialty contact lenses — including RGP, hybrid, and scleral lenses — tailored to the unique shape of each patient's cornea. Where surgical treatment is appropriate, we work alongside ophthalmologists and refer accordingly.

If you have been diagnosed with keratoconus or an irregular cornea, you are not alone, and there are effective ways to keep your vision clear and comfortable. You can book an appointment at our clinic at The Cathay, beside Dhoby Ghaut MRT, and we can guide you through monitoring and the lens options best suited to your eyes. You can also explore the other eye health conditions we help manage.