Keratoconus (pronounced keh-rah-toe-cone-us) is an eye condition that affects the cornea on the front of your eye. It usually starts in your teens or 20s and generally worsens over time, finally becoming stable by the time you reach 40.
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As the condition progresses, it causes changes in the regular shape, strength, and thickness of the cornea. The way this affects your sight will depend on the severity of these corneal changes, so that some people experience fewer sight problems than others. It is usually present in both eyes, although one eye may be more affected than the other.
This page contains a summary of our information on keratoconus. To read our full information, download our factsheet:
Living with keratoconus – Reena’s story
In this video, Reena talks about her experience of keratoconus, including the treatment she has had.
The cornea and keratoconus
Your cornea is important for sight. A healthy cornea has a regular dome-shape and is made up of several layers. It is normally strong, smooth, and transparent.
The largest, middle section of the cornea is called the stroma, and it’s made up of many regular-shaped bundles of collagen which are firmly joined together, giving the healthy cornea its strength. The cornea’s regular domed shape enables it to focus light to give you clear vision.
If you have keratoconus, the collagen bundles are affected within your cornea, so that the cornea becomes weaker and thinner nearer its centre, or just off centre. These changes in corneal thickness lead to an outward bulging, causing an irregular cone-like corneal shape to develop.
What causes keratoconus?
The cause of keratoconus is not completely understood. It’s not caused by an infection or inflammation. Keratoconus is usually diagnosed when someone is in their late teens or early twenties, and it affects men and women equally. It is more common in non-Caucasian people.
Keratoconus is not considered to be an inherited condition but for around 10% (1 in 10) of people who have keratoconus, it does affect more than one member of their family. However, most people have no family history of the condition.
It’s possible that people who have allergies might be more likely to develop keratoconus. Allergies can cause your eyes to become itchy and uncomfortable, making you more likely to rub them.
How does keratoconus affect sight?
Keratoconus can affect different people to different extents, but it does not cause blindness.
In the very early stages of the condition, your vision may not be affected very much at all. However, as your keratoconus progresses and your cornea changes its shape, your vision will become more blurred.
You may be more sensitive to light (photophobic) and experience glare, leading to discomfort and difficulty seeing things in brighter lit conditions.
How is keratoconus usually managed?
Where keratoconus is mild, you may achieve a good level of vision just by wearing glasses. However, if your cornea continues to become steeper and more cone-shaped, your sight may be better when you wear contact lenses. Contact lenses sit on the front of your eye, providing a regular front surface on the cornea and masking the irregularities due to keratoconus.
Contact lens wearers with keratoconus usually wear rigid gas permeable (RGP) lenses. However, there are various types of specialised contact lenses that can be fitted. Your optometrist will be able to advise which is the best option for you.
Are there any treatments for keratoconus?
Corneal crosslinking (CXL)
Corneal crosslinking (CXL) is the only clinically proven treatment that can stop keratoconus from getting worse by stabilising the shape of your cornea, and it is available on the NHS. It is most effective in treating keratoconus in its early stages when there are signs your keratoconus is progressing.
CXL works by using riboflavin drops (vitamin B2), ultraviolet A (UVA) light and oxygen to strengthen the cornea and prevent further changes in corneal shape and irregularity. The treatment aims to halt keratoconus progression so that your vision does not worsen any further.
CXL is less likely to be suggested as you get older. This is because crosslinking occurs naturally as you age, typically stabilising your corneal shape by your mid-30s.
For some people, combinations of CXL and a specialised laser treatment called TransPRK can be used. This combination of treatments stabilises the keratoconus to prevent further deterioration and helps to make the corneal shape more regular as well.
More information on CXL can be found by downloading the keratoconus factsheet.
Intracorneal ring segments (ICRS)
If your keratoconus has progressed beyond the stage at which combined CXL and TransPRK are helpful, intracorneal ring segments (ICRS) can be used to improve your vision. The procedure involves implanting two C-shaped rings in the corneal stroma to flatten the central cornea and give it a more regular shape.
You might also be offered CXL a few months later, as a follow-on procedure, to “hold” the corneal shape achieved by the ICRS.
Complications of keratoconus - corneal hydrops
Corneal hydrops is a rare complication of keratoconus which gives your cornea a milky, cloudy appearance and makes your vision get worse very quickly, even when wearing a contact lens. It occurs when the aqueous fluid from inside your eye enters your corneal stroma through breaks at the back of the cornea as your keratoconus has progressed. Your eye feels more uncomfortable, even painful, and becomes red and watery and your sensitivity to light increases.
These breaks in your cornea will usually take two to three months to heal and you’ll be advised not to wear your contact lenses while your eye is recovering. Your ophthalmologist might suggest injecting a special gas behind your cornea to stop further aqueous fluid from passing through it.
Once the breaks have healed most people find that their vision improves again.
Corneal transplant (keratoplasty)
A corneal transplant is surgery to remove all or part of a damaged cornea and replace it with healthy, clear corneal tissue from the eye of a donor who has died. Corneal transplants are very successful in treating keratoconus and remain a good treatment option if you already have advanced keratoconus.
There are two types of corneal transplant which are appropriate for treating keratoconus:
- Deep anterior lamellar keratoplasty (DALK), where only the outer layers of the cornea are replaced
- Penetrating keratoplasty (PK), which is a ‘full thickness’ transplant, where all the layers of your cornea are replaced.
Your ophthalmologist will be able to tell you which type of corneal transplant is best for you.
Being diagnosed with an eye condition can be very upsetting. You may find that you are worried about the future and how you will manage with a change in your vision. We’re here to support you every step of the way, and to answer any questions you may have – just get in touch with our Sight Loss Advice Service
Having keratoconus can mean your sight is variable from day to day or even within the same day. When your vision is reduced, you may find some tasks, such as reading written text, are made easier by making things bigger and bolder. Using contrasting colours can also help, for example, when making the edges of steps stand out. You’ll be more comfortable too, if the lighting around you and the devices you’re using are not causing you glare.
You can also find out tips for making the most of your sight by downloading our booklet:
UK Keratoconus Self Help and Support Association is a registered charity that works to raise awareness of keratoconus, as well as providing information and support for people in the UK affected by the condition.
Page last reviewed: Sept. 1, 2022
Next review due: Dec. 31, 2022