What Causes Keratoconus? Genetic Predisposition, Eye Rubbing, Medical Conditions and Hormonal Changes

“Why has this happened to me?” is usually one of the first things people ask when they’re told they have keratoconus. And it’s a completely understandable question. But the frustrating truth is that keratoconus doesn’t have one simple cause.  

It’s more like several things coming together at once – a bit of bad luck with your genes, possibly some habits you didn’t realise were harmful and sometimes hormonal changes happening at just the wrong time. 

At Bellamy Eyecare in Leicester and Irthlingborough, we’ve been helping people understand their keratoconus for more than 25 years. While we can’t always explain exactly why it’s happened to you specifically, understanding the main factors helps you protect your vision and know what to watch for in your children. 

It’s usually several things at once 

Think of keratoconus a bit like getting a cold. You don’t just catch a cold because you were near someone who was ill. You catch it because you were near someone ill AND you were tired AND it was winter AND your immune system was a bit run down. Several factors had to line up. 

Keratoconus works similarly. You might have inherited corneas that are more vulnerable than average. You might have rubbed your eyes a lot over the years without realising the damage it could cause. You might have developed it during puberty when hormones were all over the place.  

Usually, it’s not just one thing – it’s several factors coming together. 

That’s why keratoconus can run in families but doesn’t affect everyone and why it typically starts at particular ages. 

Does keratoconus run in families? 

Yes and no. It’s complicated. 

About 1 in 10 people with keratoconus have a close relative who also has it – a parent, brother, sister or child. That’s much higher than you’d expect by chance, so there’s definitely something genetic going on. 

But that also means 9 out of 10 people with keratoconus don’t have any family history of it at all. So even if your parents’ vision is perfect, you can still develop keratoconus. 

What’s being inherited? 

You’re not inheriting keratoconus exactly. You’re inheriting corneas that are more vulnerable – a bit like how some people inherit bones that break more easily, or skin that burns more quickly in the sun. 

Scientists have found lots of different genes that seem to be involved, all doing different jobs in building and maintaining your cornea. There’s no single keratoconus gene that definitely causes it. Instead, you might inherit a combination of small variations that make your corneas more susceptible to damage. 

What this means for your family 

If you have keratoconus, your children have a higher risk than average of developing it too. But ‘higher risk’ doesn’t mean ‘definitely will get it’. Most children of keratoconus patients never develop the condition. 

The sensible approach is to have your children’s eyes checked properly from their early teens onwards. We usually recommend a detailed examination including corneal topography (a special scan that maps the shape of the cornea) starting around age 12-14. That’s when keratoconus typically begins if it’s going to develop. 

Early detection makes an enormous difference to outcomes so catching it young gives your children the best possible chance of managing it successfully. 

The eye rubbing connection 

This is where the research has become really interesting in recent years. There’s growing evidence that chronic, vigorous eye rubbing might be one of the most important factors in keratoconus development. 

Your cornea is incredibly thin – about half a millimetre, which is slightly thinner than a credit card. When you rub your eyes hard and repeatedly over months and years, you’re putting direct mechanical pressure on something extremely delicate. 

What happens when you rub your eyes? 

The first few times don’t change much. But keep doing it, especially in the same spot, and eventually it starts to stretch and weaken where you’ve been pressing. 

That’s how your cornea responds. Repeated rubbing triggers a cascade of problems: 

• The tissue gradually thins where you’re applying pressure. 

• Your body releases enzymes that break down the cornea’s structural proteins. 

• The weakened area becomes more vulnerable to further damage. 

• A vicious cycle develops where a weaker cornea deforms more easily with each rub. 

Some researchers now think that people who never rub their eyes don’t develop keratoconus, even if they have the genetic vulnerability. The phrase they use is ‘no rub, no cone’. 

Why is one eye usually worse with keratoconus? 

If you have keratoconus, you’ve probably noticed one eye is worse than the other. The eye rubbing theory explains this perfectly. 

Most people unconsciously rub one eye more than the other – often the eye on the side they sleep on, or the eye that gets itchier if they have allergies. That eye gets more mechanical stress so it develops more damage. 

How to stop rubbing your eyes 

The first step is becoming aware you’re doing it. Many people rub their eyes unconsciously – when they’re tired, when they’re concentrating or during the night while sleeping. 

Work out what makes you rub: 

• Itchy eyes from allergies? 

• Dry, irritated eyes from too much screen time? 

• Tiredness making your eyes feel strained? 

• Just a habit? 

Then address the trigger: 

• If it’s allergies, see your GP about antihistamine tablets or eye drops. 

• If it’s dry eyes, use preservative-free lubricating drops regularly. 

• If your eyes feel tired, take screen breaks and blink more often. 

• When you feel the urge to rub, use a cool, damp flannel on closed eyelids instead. 

If you tend to rub during sleep, try sleeping on your back rather than face down into the pillow. Some people even wear protective glasses at night. 

The most important thing to understand is that even if eye rubbing didn’t start your keratoconus, continuing to rub will almost certainly make it worse. Stopping now protects the vision you have left. 

Hormones and timing 

Have you noticed that keratoconus typically begins during the teenage years? That’s not a coincidence. It’s almost certainly connected to hormonal changes during puberty. 

Puberty and keratoconus 

Keratoconus usually starts somewhere between ages 10 and 25, with most people noticing symptoms in their teens or early twenties. This matches perfectly with puberty, when hormone levels – particularly oestrogen – are changing dramatically. 

Scientists have discovered that your cornea has oestrogen receptors, which means it responds directly to hormone levels in your body. When oestrogen levels rise during puberty, your cornea may become softer and less rigid. If you already have corneas that are genetically vulnerable, this softening might be enough to tip them over the edge. 

Hormones probably don’t cause keratoconus on their own but they seem to influence when and how quickly it develops in people who are already susceptible. 

Pregnancy can make things worse 

Many women with keratoconus notice their vision getting worse during pregnancy, particularly in the last few months. This isn’t your imagination. 

During pregnancy, your oestrogen levels increase enormously. All that oestrogen is preparing your body for childbirth by softening connective tissues so your pelvis can expand. Unfortunately, your cornea is made of connective tissue too so it softens along with everything else. 

A softer cornea bulges more easily. If you already have keratoconus, this can mean rapid progression during pregnancy. 

The good news: 

• Not every woman with keratoconus gets worse during pregnancy. 

• When it does happen, the changes sometimes reverse after you’ve given birth. 

• If you’ve had corneal cross-linking or a transplant before pregnancy, you’re very unlikely to have problems. 

The bad news: 

• You can’t have corneal cross-linking during pregnancy because nobody knows whether it’s safe for the baby. 

• If you’re planning a pregnancy and your keratoconus is progressing, it makes sense to consider cross-linking first to stabilise things. 

At Bellamy Eyecare, we monitor pregnant women with keratoconus carefully throughout their pregnancy and adjust their contact lenses if needed. Most get through it fine with just a bit of extra attention. 

Other hormonal changes 

Your thyroid hormone also seems to affect how stiff or flexible your cornea is, though we’re still learning exactly how this works. Some women notice changes in their keratoconus around menopause, though less research exists on this compared to pregnancy. 

The main point is that hormones clearly influence keratoconus, even if we don’t understand all the details yet. 

Allergies and keratoconus 

There’s a very strong link between keratoconus and allergic conditions like hay fever, eczema, and asthma. Far more people with keratoconus have allergies than you’d expect by chance. 

Why? Probably two reasons. 

1. Allergies make your eyes itchy, so you rub them more. We’re back to the mechanical damage problem. 
2. Allergic conditions create inflammation throughout your body, including in your eyes. Your tears and cornea contain higher levels of inflammatory proteins when you have allergies. These proteins might directly damage corneal structure, making it more vulnerable to other problems. 

Managing allergies matters 

If you have keratoconus (or are at risk because it runs in your family), getting your allergies under control is genuinely important. It’s not just about comfort – it’s about protecting your corneas. 

See your GP about: 

• Antihistamine tablets or nasal sprays. 

• Prescription-strength eye drops for itchy eyes. 

• Immunotherapy if your allergies are severe and persistent. 

The better controlled your allergies are, the less you’ll rub your eyes and the more you’re protecting your vision long-term. 

Other medical conditions 

A few other conditions turn up more often in people with keratoconus: 

1. Down’s syndrome – people with Down’s syndrome develop keratoconus much more frequently than average, though nobody’s entirely sure why. 
2. Ehlers-Danlos syndrome – this condition affects the collagen throughout your body, including in your cornea. Weaker collagen means a more vulnerable cornea. 
3. Sleep apnoea – there seems to be a link with sleep apnoea, possibly because of the sleeping positions involved or because both conditions involve tissues that are more ‘floppy’ than they should be. 

Most people with keratoconus don’t have any of these conditions but if you do, it’s worth being extra vigilant about your eye health. 

Lifestyle factors 

A few everyday things might contribute to keratoconus risk, though the evidence is less strong: 

1. Sun exposure – chronic UV exposure might damage your cornea over time through something called oxidative stress. Wearing good sunglasses makes sense anyway and it might help protect your corneas too. 
2. Air pollution – if the air is full of irritants, your eyes get more irritated, so you rub them more. It’s an indirect connection, but it might matter. 
3. Too much screen time – staring at computers or phones for hours makes your eyes dry and tired. Dry, tired eyes get rubbed more. Again, it’s indirect but worth thinking about if you spend all day on screens. 

What should you actually do about all this? 

Understanding causes is interesting but what matters is what you do with the information. 

If you’ve been diagnosed with keratoconus: 

• Stop rubbing your eyes. This is the single most important thing. 

• Get your allergies properly managed if you have them. 

• Wear sunglasses when you’re outside. 

• Come for regular check-ups so we can spot any progression early. 

If keratoconus runs in your family: 

• Make sure your children have proper eye examinations from their early teens. 

• Watch out for signs like frequently changing prescriptions or complaints about distorted vision. 

• Don’t panic – most children of keratoconus patients never develop it themselves. 

If you’re pregnant and have keratoconus: 

• Let us know so we can monitor you more carefully. 

• Don’t worry if your vision changes – it often settles after birth. 

• Come in if things change suddenly rather than waiting for your scheduled appointment. 

Getting a proper assessment for keratoconus  

At Bellamy Eyecare, our comprehensive eye examinations take 45 minutes and include advanced corneal topography and OCT scanning. These scans can detect tiny corneal changes long before your vision is obviously affected. 

Early detection genuinely matters. The earlier we spot keratoconus, the more options we have for slowing it down and managing it successfully. Cross-linking works best when done early. Specialist contact lenses are easier to fit before corneal changes become severe. 

We’ve been managing keratoconus for more than 25 years across the East Midlands. We understand the condition thoroughly and can explain things in a way that makes sense without drowning you in jargon. 

If you’re worried about keratoconus – whether you’ve noticed symptoms, have family history or have already been diagnosed – getting proper specialist assessment is the sensible next step. 

Contact us to arrange a comprehensive assessment at either our Leicester or Irthlingborough practice. 

Keratoconus FAQs: Causes, Risks, and What to Do Next

1. What is keratoconus and how does it affect the cornea?

Keratoconus is a progressive eye disorder where the cornea – the clear, dome-shaped surface of your eye – becomes thin and gradually bulges outward into a cone shape. This irregular curvature distorts light entering the eye, often leading to blurry or distorted vision, increased sensitivity to light and difficulty seeing clearly at night.

2. What are the early signs and symptoms of keratoconus?

Common symptoms include frequent changes in your glasses or lenses prescription, blurry eyesight, ghosting or double vision, eye strain and difficulty with night vision. If you notice these changes, a detailed diagnosis by an ophthalmologist or eye care specialist is essential.

3. Is keratoconus hereditary or genetic?

Yes, keratoconus can be hereditary but it doesn’t always run in families. About 1 in 10 individuals with the disorder have a close relative who also has it. Research shows certain mutations and inherited differences in collagen structure may contribute to corneal weakness, making it more vulnerable to change.

4. Does eye rubbing cause keratoconus?

Chronic eye rubbing is one of the strongest environmental factors linked to keratoconus. Rubbing applies direct pressure to the corneal surface, leading to thinning, steepening and potentially worsening of the condition. Managing allergies (a common trigger for rubbing) is crucial to protect your vision.

5. Can hormones or medical conditions influence keratoconus development?

Yes – hormonal changes during adolescence, pregnancy and even menopause can affect the structure of the cornea. Certain medical conditions like Down syndrome, Ehlers-Danlos syndrome and sleep apnoea are also associated with higher occurrence of keratoconus due to systemic connective tissue disorders.

6. How is keratoconus diagnosed?

Keratoconus is diagnosed using advanced techniques like corneal topography, retinoscopy and slit-lamp examination. These tools detect changes in corneal thickness, curvature and structure, often before symptoms become severe. At our Leicester and Irthlingborough practices, we include OCT and videokeratography as part of our assessments.

7. What treatments are available for keratoconus?

Treatment depends on the severity and stage of the condition. Early stages may be managed with specialist contact lenses, while progressive cases might require corneal cross-linking to stabilise the corneal structure. In advanced stages, keratoplasty (corneal transplant) or other surgical interventions may be considered.

8. Can lifestyle or environmental factors increase risk?

Yes. UV light, air pollution and long hours on screens may contribute to keratoconus progression through increased eye irritation and oxidative stress from free radicals. Wearing sunglasses and taking screen breaks can reduce unnecessary eye strain and rubbing.

9. Why does keratoconus often start during the teenage years?

The onset often coincides with puberty, suggesting a hormonal role, particularly due to the effect of oestrogen on the cornea’s collagen structure. This makes the cornea softer and more prone to deformation in genetically susceptible individuals.

10. How can I protect my child if keratoconus runs in the family?

If you have keratoconus, your child has a higher risk factor. Start regular eye visits from ages 12–14 and ask about corneal topography scans. Early diagnosis offers more effective management options and can help preserve their visual acuity and function long-term.

Leicester Practice
156 Fosse Road North, Leicester, LE3 5ES
Tel: 0116 2531750 

Irthlingborough Practice
24 High Street, Irthlingborough, NN9 5TN
Tel: 01933 653226