You get new glasses. Six months later, they’re not quite right anymore. Another test, another prescription and still that faint smearing around headlights at night that never fully goes away. If that pattern sounds familiar, it’s worth knowing about keratoconus, a corneal condition that often hides behind years of “just another prescription change”.
Keratoconus affects far more Australians than most people realise. A landmark population study of 20-year-olds in Western Australia (the Raine Study, published in Ophthalmology) found a prevalence of 1 in 84, one of the highest rates reported anywhere in the world. Yet because early keratoconus symptoms mimic ordinary short-sightedness and astigmatism, many people go years without a proper diagnosis.
This guide walks through the early signs, the advanced symptoms, how keratoconus differs from regular astigmatism and what happens once it’s picked up. The short version: it’s manageable when caught early, and a standard eye test with corneal imaging is all it takes to find out.
What Is Keratoconus and Why Does It Distort Your Vision?
Your cornea is the clear front window of your eye. In a healthy eye it holds a smooth, evenly rounded dome shape, which lets it focus light cleanly onto the retina. In keratoconus, the cornea gradually thins and weakens. Under the normal pressure inside the eye, that weakened tissue starts to bulge forward into a cone shape.
A cone doesn’t focus light the way a dome does. Instead of one crisp focal point, light scatters across the retina, which is why keratoconus symptoms centre on distortion: blur, ghosting, streaking and glare rather than simple fuzziness.
Keratoconus usually starts in the teens or twenties, tends to affect both eyes (often one worse than the other) and progresses over years rather than weeks. That slow pace is exactly why the early signs are so easy to write off.
Early Keratoconus Symptoms to Watch For
The first signs of keratoconus rarely announce themselves. They creep in as small frustrations that feel like normal vision problems. Here’s what our clinical team looks for.
Blurred and distorted vision that glasses can’t fully fix
This is the hallmark early symptom. Straight lines can look slightly bent or wavy, edges of text seem to smear and even a brand-new prescription leaves things a little “off”. Standard glasses correct a smooth focusing error. They struggle with an irregular cone, so the blur never fully resolves no matter how carefully your script is tuned.
Frequent prescription changes
Most adult prescriptions settle down and change slowly. With keratoconus, the cornea keeps reshaping, so the prescription keeps chasing it. If your astigmatism is climbing at every visit, especially through your late teens or twenties, that pattern itself is a red flag worth investigating with corneal imaging.
Light sensitivity, glare and halos at night
An irregular cornea scatters light, and nowhere is that more obvious than night driving. Oncoming headlights flare into starbursts, streetlights grow halos and bright days feel harsher than they should. Many people with early keratoconus notice their night vision deteriorating well before their daytime vision does.
Ghosting and double vision in one eye
Cover one eye and look at a bright object on a dark background, like the moon or a distant light. If you see a faint second image or a smeared “ghost” trailing off it, that’s called monocular diplopia, and it’s a classic keratoconus symptom. Ordinary double vision usually disappears when you close one eye. Ghosting from keratoconus doesn’t, because the problem sits within the cornea itself.
Headaches and eye strain often ride along with these symptoms too. When your eyes are working overtime to sharpen an image that can’t be sharpened, the squinting and focusing effort commonly ends in tension headaches by day’s end.
Advanced Keratoconus Symptoms
Left undetected, the cone becomes steeper and the symptoms harder to ignore. Advanced keratoconus symptoms include:
Munson’s sign
When the cone becomes pronounced, it can physically push the lower eyelid outward. Looking down, the lid takes on a visible V-shaped bulge. This is called Munson’s sign, and by the time it appears the condition is well established.
Sudden clouding of vision (corneal hydrops)
In a small number of advanced cases, the stretched inner layer of the cornea develops a break that lets fluid rush into the corneal tissue. Vision clouds over quickly and the eye can become painful, red and severely light sensitive. This is called corneal hydrops. It usually settles over weeks to months, but it needs prompt professional care, so treat sudden clouding as an urgent reason to be seen.
Contact lenses that no longer fit
Standard soft lenses drape over the cornea, so as the cone steepens they stop sitting properly. Lenses that pop out, move around or feel increasingly uncomfortable can signal that the corneal shape has changed underneath them.
One thing worth stating clearly: keratoconus very rarely causes complete blindness. Even severe cases retain useful vision, and modern treatment means the vast majority of people maintain good functional sight for life. The point of early detection is keeping your vision crisp with the simplest treatment possible.
Keratoconus vs Astigmatism Symptoms: How to Tell the Difference
Keratoconus is frequently mistaken for plain astigmatism, and for good reason. Both involve a cornea that isn’t perfectly round, and both cause blur and distortion. The differences sit in the pattern:
- Regular astigmatism is stable, symmetrical and fully correctable with glasses. Your prescription might barely move for a decade.
- Keratoconus is progressive and irregular. The prescription keeps changing, glasses never quite get you to sharp and symptoms like ghosting, halos and worsening night vision keep building.
Basically, astigmatism that keeps increasing, particularly in a young person, deserves corneal imaging rather than just a stronger script.
What Causes Keratoconus?
No single cause has been pinned down, but research points to a mix of genetics and environment:
- Eye rubbing. This is the big modifiable one. Chronic, vigorous eye rubbing is strongly associated with keratoconus development and progression. If you have itchy eyes from allergies, treating the itch (rather than rubbing through it) matters.
- Family history. Having a parent or sibling with keratoconus raises your risk, which is why we recommend screening for close relatives of anyone diagnosed.
- Allergic conditions. Hay fever, eczema and asthma are common companions, largely because they drive the itch-and-rub cycle.
- Age. Onset is typically between the early teens and mid-twenties, with progression often slowing by the mid-thirties.
The national patient support organisation, Keratoconus Australia, is an excellent resource if you or a family member has been diagnosed and wants to understand the condition further.
Keratoconus Symptoms in Children and Teenagers
Keratoconus in children deserves special mention because kids rarely complain about vision they’ve never known to be different. Watch for:
- Sitting closer to screens or holding devices near the face
- Squinting, frequent blinking or constant eye rubbing
- Slipping performance at school or reluctance to read
- Rapidly increasing short-sightedness or astigmatism at each eye test
Keratoconus tends to progress fastest in young eyes, so early detection matters most in this group. If your child’s prescription is climbing quickly, ask about corneal imaging at their next visit. It’s quick, painless and definitive.
How Optometrists Diagnose Keratoconus
The reassuring part: diagnosing keratoconus is straightforward with the right equipment. A comprehensive eye exam can pick it up long before you’d spot it yourself, sometimes years before symptoms become obvious. Assessment typically includes:
- Corneal imaging. Detailed scans map the shape and thickness of your cornea point by point. These scans reveal the early steepening and thinning that define keratoconus. Very early or subtle cases (sometimes called forme fruste keratoconus) can only be detected this way.
- OCT scanning. Optical coherence tomography gives a cross-sectional view of the cornea’s structure, which helps track thickness changes over time.
- Refraction and vision testing. Irregular astigmatism that won’t correct cleanly with lenses is a strong clue in itself.
At EyeSelect, our Browns Plains and Forest Lake practices are equipped with OCT scanning and digital imaging as part of a comprehensive eye exam, which is bulk-billed through Medicare for eligible patients. Detecting keratoconus doesn’t cost you anything except half an hour.
Keratoconus Treatment: What Happens After Diagnosis
A keratoconus diagnosis is not the bad news it sounds like. Treatment depends on the stage:
- Early keratoconus can often be managed with glasses or standard soft contact lenses while the shape remains mild.
- Progressing keratoconus may be referred for corneal cross-linking, a procedure performed by an ophthalmologist that strengthens the cornea and halts progression. This is why early detection matters: cross-linking preserves the vision you have.
- Established keratoconus is usually best corrected with specialist contact lenses. Rigid gas permeable and scleral lenses create a smooth new optical surface over the irregular cornea, and the improvement in clarity often surprises people who’ve spent years squinting through glasses.
Fitting these lenses is precise work. The lens has to vault the cone, land comfortably and stay stable through a full day of wear, which takes detailed measurement and a few refinement visits. Our contact lens fitting service covers this process from initial assessment through to teaching you insertion, removal and care. Only a small percentage of people with keratoconus ever need a corneal transplant, and it’s generally reserved for cases where lenses can no longer provide functional vision.
When to Book an Eye Test
See an optometrist promptly if you notice:
- Blur or distortion that new glasses don’t fix
- Ghosting or double vision that persists with one eye covered
- Worsening glare, halos or night vision
- A prescription that keeps changing year after year
- Sudden clouding of vision in one eye (treat this as urgent)
Blur that affects one eye more than the other is common in keratoconus, though it has plenty of other causes too.
If any of the symptoms in this guide feel familiar, don’t sit on it. Book an eye test at Browns Plains (07 3800 8700) or Forest Lake (07 3278 7341). A comprehensive exam with corneal imaging will give you a clear answer, and catching keratoconus early keeps every treatment option on the table.
Keratoconus Symptoms: Frequently Asked Questions
What are the first symptoms of keratoconus?
The earliest keratoconus symptoms are mild blurring and distortion of vision, increasing sensitivity to light and glare, ghosting around bright objects and a prescription that keeps changing. Night vision often deteriorates first.
Can keratoconus cause blindness?
Keratoconus very rarely causes total blindness. It can cause significant vision loss if untreated, but specialist contact lenses, corneal cross-linking and (in a small minority of cases) corneal transplant preserve useful vision for the vast majority of people.
Does keratoconus cause headaches?
It can. The constant effort of squinting and straining to focus through a distorted cornea commonly leads to eye strain and tension headaches, particularly after reading, screen work or driving.
How is keratoconus different from astigmatism?
Regular astigmatism is stable and fully correctable with glasses. Keratoconus causes irregular astigmatism that progresses over time and cannot be fully corrected with glasses. Corneal imaging distinguishes the two.
At what age do keratoconus symptoms start?
Symptoms typically begin between the early teens and mid-twenties. The condition usually progresses for 10 to 20 years before slowing, which is why it progresses fastest and needs closest monitoring in younger patients.
What is forme fruste keratoconus?
Forme fruste keratoconus is a very early or subclinical form of the condition where the cornea shows subtle shape changes on imaging but vision is still normal. It causes no symptoms and is usually found during corneal scans, often before laser eye surgery assessments.
Can children get keratoconus?
Yes. Keratoconus can begin in childhood, and it tends to progress faster in younger eyes. Signs in children include frequent eye rubbing, squinting, sitting close to screens and rapidly increasing prescriptions. Early corneal imaging is recommended for children with these signs.
This article is for educational purposes and is not a substitute for professional optometric advice. Book an appointment for a personalised assessment.