Catching keratoconus early: why a changing prescription in a teenager matters
If there is one message worth carrying about keratoconus, it is this: the earlier it is found, the more of your vision can be protected. Keratoconus typically begins in the teenage years and tends to progress fastest during adolescence and the early twenties — which means the window where treatment does the most good is often the very window where a young person is least likely to mention that their sight is changing.
What keratoconus is doing, and why age matters
In keratoconus the cornea — the clear front window of the eye — gradually thins and bulges into an irregular cone. That changing shape blurs and distorts vision and makes a spectacle prescription drift. Research on keratoconus in children and teenagers has found that the disease tends to be more aggressive in younger patients than in adults, which is exactly why guidelines emphasise early diagnosis and prompt treatment when progression is shown (Buzzonetti et al., Cornea, 2020). The reason is simple: corneal cross-linking, the treatment that can slow progression, protects the cornea you still have — it cannot rebuild a cone that has already advanced.
What to watch for
Keratoconus can be quiet at first. Signs worth taking seriously, especially in a teenager, include:
- A spectacle or contact lens prescription that keeps changing, particularly increasing astigmatism
- Blurred, smeared or “ghosted” vision that glasses do not fully fix
- Increased glare and haloes around lights, or worsening night vision
- Frequent eye rubbing — which is strongly associated with keratoconus and worth gently discouraging
- A family history of keratoconus, or conditions such as eczema, asthma and allergies that go with habitual eye rubbing
None of these on its own means keratoconus. But a prescription that will not settle is the classic early clue, and it is the one that should prompt a proper look rather than simply a stronger pair of glasses.
The step that counts: a corneal map
Ordinary eye tests are not designed to catch early keratoconus. What detects it — often before vision is badly affected — is corneal tomography: detailed imaging that maps the front and back surfaces of the cornea and its thickness, using systems such as Scheimpflug (Pentacam) and swept-source OCT imaging. Sequential maps over time are also how progression is proven, which is what a surgeon needs before recommending cross-linking. This is why an optometrist who works in keratoconus, with the right imaging, is the right front door.
Getting checked in New Zealand
New Zealand has one of the higher rates of keratoconus internationally, and early detection is a real equity issue here. If a teenager in your whānau has a prescription that keeps changing — or a family history — a corneal map is the sensible next step, not a wait-and-see. The keratoconus clinic at Rose Optometry in Hamilton offers Pentacam and ANTERION corneal mapping, monitors progression, refers for cross-linking when it is indicated, and fits the scleral lenses that restore vision. You can book a keratoconus assessment directly, or ask your optometrist to refer you.
This article is general information, not a substitute for a clinical assessment of your own eyes.
References
Sourced and verified via PubMed.
- Buzzonetti L, Bohringer D, Liskova P, Lang S, Valente P. Keratoconus in Children: A Literature Review. Cornea. 2020;39(12):1592-1598. PMID 32740004. DOI
