Keratoconus explained: symptoms, diagnosis and modern treatment in the UK

Keratoconus is a progressive eye condition in which the normally dome-shaped cornea gradually thins and bulges outward into a cone shape. That distortion of the front surface of the eye scatters and misdirects light as it enters, so vision becomes increasingly blurred, distorted and difficult to correct with ordinary glasses. It typically begins in the teens or early twenties and, if left untreated, can progress steadily for a decade or more.

The good news is that keratoconus is now one of the most treatable corneal conditions in the UK. Early diagnosis and modern treatments — particularly corneal cross-linking — mean the vast majority of patients can preserve useful vision for life and avoid ever needing a corneal transplant.

What causes keratoconus?

The exact cause is not fully understood, but keratoconus is thought to involve a combination of genetic predisposition, biomechanical weakness of the cornea and mechanical stress from eye rubbing. Persistent, forceful eye rubbing — often driven by allergy, atopic eczema or asthma — is the single most important modifiable risk factor. Any child or young adult with itchy, allergic eyes should be encouraged not to rub and should be assessed if vision changes.

Early symptoms

The earliest signs are often subtle: a prescription that changes every few months, increasing astigmatism, blurred or ghosted vision that glasses cannot fully correct, and glare or starbursts around lights at night. Some patients notice that one eye becomes significantly worse than the other. If you or your optometrist notice a rapidly changing prescription in your teens or twenties, keratoconus should always be considered.

How keratoconus is diagnosed

Diagnosis is made in clinic using corneal topography and tomography — imaging that maps the exact shape and thickness of the cornea. A Pentacam or similar scanner can detect keratoconus long before it becomes visible on a standard eye examination, which matters because early treatment gives the best long-term result. A slit-lamp examination, refraction and measurement of best-corrected vision complete the picture.

Corneal cross-linking

Corneal cross-linking (CXL) is the gold-standard treatment for progressive keratoconus. It is a 30–60 minute outpatient procedure that combines riboflavin (vitamin B2) eye drops with a controlled dose of ultraviolet A light. This creates new chemical bonds between the collagen fibres of the cornea, stiffening it and stopping progression in more than 90% of eyes. Cross-linking does not reverse existing distortion, but it stops it getting worse — which is why early treatment is so valuable.

Contact lenses and intracorneal ring segments

For patients whose vision cannot be corrected with glasses, specialist contact lenses — rigid gas-permeable, scleral or hybrid designs — can give excellent functional vision by masking the irregular corneal surface. In selected patients, intracorneal ring segments (ICRS) — small clear plastic arcs inserted into the cornea — can flatten the cone and make contact lens or spectacle correction more effective.

When a corneal transplant is needed

Fewer than 10% of patients with keratoconus now progress to needing a corneal transplant, thanks to the widespread availability of cross-linking. When a transplant is required, modern techniques such as deep anterior lamellar keratoplasty (DALK) replace only the diseased front layers of the cornea, preserving the patient's own healthy inner layer and giving excellent long-term results.

Living well with keratoconus

The single most important thing you can do if you have keratoconus — or a family history of it — is to stop rubbing your eyes. Treat any underlying allergy or dry eye. Attend follow-up appointments so that any progression is caught early, and ask your consultant whether cross-linking is appropriate for your eyes. Most patients live entirely normal lives, drive, work, and enjoy sport, provided the condition is monitored and stabilised.

Related reading: learn more about laser vision correction, lens replacement surgery, our full range of eye services, or read how laser eye surgery works and is laser eye surgery safe?.

If you would like a corneal topography assessment or a second opinion on keratoconus, you can book a free 15-minute call with a UK consultant ophthalmologist or request a full consultation.