Keratoconus: symptoms, diagnosis and treatments

Keratoconus is a common corneal disease that progressively distorts the cornea into a cone shape, causing reduced vision and irregular astigmatism. Detected early, it can be stabilised effectively. Here, in plain language, are its signs, how it is diagnosed and the treatments available at each stage.

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What is keratoconus?

The cornea is the transparent window at the front of the eye. In keratoconus it gradually thins and bulges, taking on an irregular cone shape. This distortion disturbs the way light enters the eye and causes irregular astigmatism that is difficult to correct with glasses alone.

Keratoconus usually begins in adolescence or young adulthood, then tends to stabilise with age. It generally affects both eyes, often asymmetrically. Repeated eye rubbing and an allergic background are well-established aggravating factors: not rubbing your eyes is a simple and essential measure.

What are the symptoms?

• Blurred or distorted vision that worsens and is poorly corrected by glasses.
• Frequently changing astigmatism, with prescriptions needing to be updated often.
• Light sensitivity, halos around light sources and difficulty at night.
• A frequent urge to rub the eyes (often associated with allergy).

How is it diagnosed?

Diagnosis relies on slit-lamp examination and above all on corneal topography and tomography, which map the curvature and thickness of the cornea. These tests detect keratoconus very early, even before vision declines, and make it possible to monitor progression over time. It is this monitoring that guides the decision to treat.

Treatments for keratoconus

Management depends on the stage and, above all, on whether the disease is progressing or stable. The aim is twofold: to stabilise the cornea and to restore vision.

1. Glasses and contact lenses

In the early stages glasses may be enough. Once irregular astigmatism sets in, well-fitted rigid or scleral lenses provide much better vision by recreating a regular optical surface.

2. Corneal cross-linking (CXL)

Cross-linking is the reference treatment to stabilise progressive keratoconus. It combines riboflavin (vitamin B2) with ultraviolet light, strengthening the collagen bonds of the cornea and making it stiffer. It does not correct vision but slows progression of the disease. It is mainly indicated in young patients whose topography shows worsening. Its main limitation: it requires sufficient corneal thickness and a cornea that is not too distorted.

3. Intracorneal ring segments

Intracorneal ring segments are small implants inserted within the thickness of the cornea to flatten it and reduce its distortion. They improve surface regularity and tolerance to contact lenses. They are suited to moderate keratoconus with a still-clear cornea; their effect is partial and they are sometimes combined with cross-linking.

4. Corneal transplantation

In advanced disease, when the cornea is too distorted or opaque and contact lenses are no longer tolerated, a corneal graft is offered. Today a deep anterior lamellar keratoplasty (DALK) is preferred: it replaces the diseased layers while preserving the patient's own endothelium, reducing the risk of rejection. See the corneal graft page.

Are you a healthcare professional? To go further: the expert course “Keratoconus & corneal ectasia” — diagnosis (topography, tomography, epithelial mapping), ABCD staging, cross-linking, intracorneal ring segments & CAIRS, double-docking DALK and acute hydrops.

This page is for general information only and does not replace a medical consultation. Treatment is always individualised after a full examination. Pr Eric E. Gabison — corneal and ocular surface surgery, Rothschild Foundation Hospital, Paris.