Keratoconus

Keratoconus symptoms

Keratoconus symptoms vary from person to person, depending on how advanced the condition is. For some, it develops quickly, while for others it progresses slowly over many years or even decades. 
 
Symptoms usually begin in the early teens to early twenties, though they can appear earlier or later. 
 
Any changes in your vision should be checked by an optometrist as soon as possible. 
 
Below are some of the main symptoms of keratoconus, depending on the stage.

Advanced symptoms of keratoconus

Here are some advanced stage keratoconus symptoms:

Visible 'pointing' eye shape

In later stages of keratoconus, the cornea appears more pointed or cone shaped, instead of being rounded with a smooth curve.

Noticing 'ghost' images

As keratoconus progresses, you may notice there are multiple 'ghost' images that surround a main image when looking at things (known as 'monocular polyopia'). These can appear scattered randomly around the main image. Over time, the way these 'ghost' images appear can change.

Very blurry keratoconus vision

Your vision gets progressively worse, with blurriness, distortion, or cloudiness making it more difficult to see clearly. 
Learn more about cloudy vision and blurry vision

Corneal scarring

As your cornea gets thinner, it can be more easily damaged. This can cause scarring on the cornea, which can make vision blurrier.
Learn more about corneal abrasion

Contact lenses no longer fit

Because your cornea has changed shape so much, it can become hard or impossible to wear normal contact lenses.

Eye discomfort

While keratoconus isn't usually painful, it can cause discomfort, throbbing, a gritty feeling or even a burning sensation for some people. 
Learn more about eye pain

Stages of keratoconus

Keratoconus may progress through four stages ‑ mild, moderate, advanced, and severe. It develops in different ways for different people. For some, keratoconus never develops beyond the mild stage, while for others it can progress to more advanced stages within a few years. In most cases, progression slows or stops by your 30s or 40s. 
 
If you have keratoconus, regular appointments with your optometrist are crucial. They can monitor any changes and help you to manage the condition.

Mild keratoconus

Your cornea starts to become thinner and bulges slightly. You will experience some problems seeing things further away and some blurring. You may also notice you're more sensitive to light.

Moderate keratoconus

The cornea takes on more of a cone shape, which is known as corneal steepening. Scarring may happen, and blurring along with visual distortion becomes more pronounced.

Advanced keratoconus

In the advanced stage, the cornea bulges more noticeably, becomes thinner, and develops scarring. You may experience increased blurring, visual distortions (such as multiple 'ghost' images), and other symptoms.

Severe keratoconus

Cornea becomes very thin and bulges outwards. Vision is often badly affected, with blurring and distortion. In some cases, a split can develop in the back layer of the cornea (called hydrops), causing painful swelling and scarring.

Causes of keratoconus

Experts still don't know exactly what causes keratoconus ‑ it's likely to be a mix of things coming together. Here are some of the main keratoconus causes that experts believe contribute to the condition.

Genetics

There is evidence that there is a genetic element to keratoconus ‑ it often runs in families. It is also more common in people who have certain genetic conditions, like Down syndrome.

Eye rubbing

People who rub their eyes a lot are more likely to develop keratoconus. Excessive rubbing can damage the cornea. People with allergies, eye infections, dry eye syndrome, or eczema may rub their eyes more often. 
Learn more about dry eye syndrome

Hormonal shifts

Keratoconus appears to be connected to hormonal changes (hormones are your body’s chemical messengers). Symptoms often begin around puberty as well as other times of rapid hormonal change, like pregnancy or menopause.

Environmental factors

Some environmental factors, such as pollen, high levels of ultraviolet light or even air pollution could be possible keratoconus causes.

Keratoconus diagnosis

If you've noticed you have symptoms of keratoconus vision, it's really important to visit your optometrist. They will do tests to diagnose what's happening. The sooner you get a diagnosis, the more your optometrist can do to help manage the condition ‑ and potentially stop it from getting worse.

Book an eye test

Medical history

Your optometrist will ask about when the symptoms began, what things look like for you, and if you notice any patterns (such as times of day it's more noticeable). They will also want to know if any of your relatives have similar issues ‑ it's worth asking around your extended family.

Visual acuity tests

Your optometrist will do some tests to check for things like short‑sightedness or astigmatism. They will usually ask you to read off a Snellen chart, where the letters go from large to small. 
Learn more about snellen charts

Slit lamp exam

A slit lamp is a powerful microscope with an attached light that lets the optometrist see your cornea very close up. 
Learn more about slit lamps

Retinoscopy

A retinoscope lets the optometrist check how well your eyes focus. It helps the optometrist work out how short‑ or long‑sighted you are. 
Learn more about retinoscopes

Keratometer

This is a device that measures the curve of your cornea. It helps with monitoring how your keratoconus is advancing. 
Learn more about keratometers

OCT scan

This powerful machine helps optometrists view the inside of your eye and can help monitor changes in shape over time. 
Learn more about OCT scans

Can keratoconus be prevented?

It's not always possible to prevent keratoconus ‑ some of the things that cause it (like genetics or hormonal changes) are out of your control. But there are some things you can do to reduce your risk. 
 
Most importantly, you should avoid excessive eye rubbing, since this can make the cornea weaker and thinner. You can also reduce exposure to environmental factors too. For example, wearing UV protected sunglasses reduces the effects of UV radiation. Staying away from things that cause allergies or taking antihistamines can also help. 
 
Having regular eye examinations can also help catch the condition early, and potentially stop it from progressing.