Keratoconus
Found early, it can usually be stopped where it is.
Overview
Keratoconus is a thinning of the cornea, the clear window at the front of the eye, which allows it to bulge forward into a cone. Vision becomes distorted rather than simply blurred: straight lines bend, lights streak, and a new pair of glasses never quite settles the problem. It usually begins in adolescence or the early twenties.
A spectacle prescription that keeps changing is often the first sign, and it is frequently missed. The earlier keratoconus is found, the more cornea there is left to protect — which is why a young patient whose prescription has shifted twice in a year deserves a scan rather than another new pair of glasses.
When to seek assessment
- A glasses or contact lens prescription that changes repeatedly
- Vision that is distorted rather than simply out of focus
- Increasing astigmatism, particularly if the axis keeps shifting
- Streaking or ghosting around lights at night
- Frequent eye rubbing, often alongside allergy or itching
- Glasses that have never quite corrected the vision in one eye
Diagnosis
How the assessment is made
Corneal tomography
The examination that matters. A scan maps the shape and the thickness of the cornea across its whole surface, front and back, and identifies the pattern well before it can be seen any other way. A standard sight test cannot do this.
Progression assessment
A single scan shows the shape today. Repeating it after an interval shows whether the cornea is changing — and it is change, not shape alone, that decides whether treatment is advised.
Ocular surface and allergy check
Eye rubbing is strongly associated with keratoconus getting worse. Where allergy or dryness is driving the rubbing, treating it is part of treating the keratoconus.
Visual assessment
How much the cornea has affected your sight, and whether spectacles, soft lenses or rigid lenses are giving you the clearest practical vision.
Treatment
Options and what each one is for
Corneal cross-linking
Riboflavin drops and controlled ultraviolet light are used to strengthen the bonds within the cornea. In most eyes it halts progression. It is advised when scans show the cornea is still changing, and it is a treatment aimed at protecting the sight you have.
What cross-linking does not do
It does not reverse the thinning that has already happened, and it does not usually improve vision. Glasses or contact lenses are still likely to be needed afterwards. Any account of the procedure that promises better sight is describing something else.
Spectacles and contact lenses
Early keratoconus is often corrected well with glasses or soft lenses. As the cornea steepens, rigid or scleral lenses give clearer vision by replacing the irregular surface with a smooth one. Lenses correct the sight; they do not stop the condition.
Monitoring without treatment
Where the cornea has been stable for years and vision is good, observation with periodic scans is a legitimate plan. Not every eye with keratoconus needs an operation.
Recovery
What to expect afterwards
First few days
Cross-linking is uncomfortable rather than painful, much like a surface graze. A protective contact lens is worn for several days and drops are used regularly. Vision is blurred during this period and most people take a few days away from work.
First month
Vision settles gradually and can fluctuate. It is normal for sight to be a little worse than before for several weeks before it returns to its previous level.
Three to twelve months
The cornea continues to remodel. Any change to your spectacle or lens prescription is made once the eye has stabilised, not before.
Long term
Periodic scans continue, because the purpose of treatment was to stop progression and the only way to confirm that is to measure it.
Questions
Frequently asked
If your question is not answered here, it is welcome in consultation — or by message before you book.
Usually not, and it is important to go in expecting that. The purpose is to stop the cornea from getting worse. Some eyes do flatten slightly over the following year and see a little better, but that is a bonus rather than the aim. You are likely to still need glasses or lenses afterwards.