Keratoconus

Keratoconus causes changes in the shape, strength, and thickness of the cornea. The way this affects your sight will depend on how much the cornea changes. Some people experience fewer sight problems than others. It is usually present in both eyes, but one eye may be worse than the other.

This page contains a summary of our information on keratoconus. To read our full information, download our factsheet:

In this video, Reena talks about her experience of keratoconus, including the treatment she has had.

Your cornea is at the front of your eye and it’s important for your 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. It’s made up of many regular-shaped bundles of collagen. These are firmly joined together, giving the healthy cornea its strength. The clear cornea allows light to pass through it. Its regular domed shape enables it to focus light to give you clear vision.

If you have keratoconus, the collagen bundles within your cornea are affected. This means your cornea becomes weaker and thinner nearer its centre, or just off centre. These changes cause an outward bulging. This causes an irregular cone-like corneal shape to develop.

Research shows that a person’s genes can play a major role in developing keratoconus. The condition affects men and women equally but is more common in non-Caucasian people.

Having allergies may make it more likely to develop keratoconus. Allergies can cause your eyes to become itchy and uncomfortable, making you more likely to rub them. Rubbing your eyes a lot over a long period of time may play a part in developing the condition. It could cause your cornea to become weaker. If your cornea is weakened, you might be more at risk of developing keratoconus. However, this doesn’t happen for everyone who rubs their eyes a lot. It’s important to seek treatment if you do have allergies that make your eyes itchy. Treatment can help you stop rubbing your eyes too much.

Keratoconus does not cause complete blindness but it can affect different people to different extents.

In the very early stages of the condition, your vision may not be affected very much at all. Your vision can become more blurred as your keratoconus progresses, and your cornea changes its shape.

You may be more sensitive to light (photophobic) and experience glare at times. You may also have difficulty with your vision when the light is dim. Photophobia and glare can lead to discomfort and difficulty seeing things in brighter lit conditions.

Early keratoconus is usually picked up by your optometrist (optician) during an eye examination. It’s important your optometrist refers you to an ophthalmologist (hospital eye doctor) early on if they suspect you have keratoconus. An ophthalmologist will diagnose and monitor your keratoconus. The shape of your cornea will be monitored over a period of time to check for signs of progression. This will identify early on whether CXL treatment is appropriate in your case.

Where keratoconus is mild, you may achieve a good level of vision just by wearing glasses or soft contact lenses. However, if your cornea continues to change shape, there may come a time when your vision with glasses isn’t as good as it could be. Your sight may be better when you wear rigid contact lenses instead.

Contact lenses sit on the front of your eye. They provide a regular front surface on the cornea. This means they mask the corneal irregularities due to keratoconus.

Contact lens wearers with keratoconus usually wear rigid gas permeable (RGP) lenses. However, there are various types of contact lenses that can be fitted. Your optometrist will be able to advise which is the best option for you.

Corneal crosslinking (CXL)

Corneal crosslinking (CXL) is a clinically proven treatment available on the NHS. It can stop progressive keratoconus from getting worse by stabilising the shape of your cornea. It is most effective in treating keratoconus in its early stages.

CXL strengthens the cornea. It prevents further changes in corneal shape and irregularity. CXL does this using riboflavin drops (vitamin B2), ultraviolet A (UVA) light and oxygen. The treatment aims to halt keratoconus progression so that your vision does not worsen any further.

As we age, natural crosslinking occurs which usually stabilises the corneal shape by your mid-30s. This reduces the need for CXL after this age.

Your ophthalmologist will advise if CXL is an appropriate treatment for you by considering:

• your age
• the shape, thickness and irregularity of your cornea
• whether your keratoconus is progressing.

In some hospitals, a specialised laser treatment called TransPRK can also be combined with CXL treatment. The CXL treatment stabilises the keratoconus to prevent it getting worse. The TransPRK laser helps to make the corneal shape more regular again. This combined treatment aims to prevent further deterioration. However, TransPRK laser is not available everywhere at the moment.

More information on CXL can be found by downloading our full keratoconus factsheet.

Corneal ring segments

Intracorneal ring segments (ICRS) and corneal allogenic intrastromal ring segments (CAIRS) are both examples of corneal implants. They are designed to improve your vision when your keratoconus has progressed. Typically, this is when combined CXL and TransPRK treatments will not be helpful on their own. CAIRS is a relatively new treatment for keratoconus. Your ophthalmologist can advise whether it is being offered in your hospital. ICRS are thin plastic semi-circular rings. CAIRS uses donor cornea prepared into semi-circular rings. These rings are then implanted into the corneal stroma. The aim of this treatment is to flatten the central cornea and give it a more regular shape. For some people, this can allow for a better contact lens fit or better vision with glasses.

Corneal hydrops is a rare complication of keratoconus. It makes your cornea look milky and cloudy and causes your vision to worsen very quickly. It happens when the aqueous fluid from inside your eye leaks into the stroma through due to breaks in a layer called Descemet’s membrane. These breaks cause sudden swelling and blurred vision that doesn’t improve with contact lenses. Your eye may become red, watery and more sensitive to light, and it can be painful.

These breaks usually heal in two to three months. During this time, you’ll be advised not to wear your contact lenses to avoid further complications. Your ophthalmologist might give you eye drops to make your eye feel more comfortable if you are in pain. They might also suggest injecting a gas behind your cornea to help seal the breaks and/or compression stitches to speed up the healing process.

After healing, vision often improves, but you might need new contact lenses if your cornea has changed shape during its recovery.

Now that CXL is more widely available, corneal transplants are a less common treatment for keratoconus. However, a corneal transplant can still be an effective treatment option for some people. This may be because your keratoconus is advanced, and contact lenses are no longer effective in maintaining your vision.

A corneal transplant is surgery to remove all or part of a damaged cornea. The damaged area is replaced with healthy, clear corneal tissue. This comes from the eye of a donor who has died. Corneal transplants are very successful in treating keratoconus. Afterwards, your eye will heal, and your vision will stabilise. However, it’s still likely you’ll need to wear glasses or contact lenses to get the best possible vision.

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), where a ‘full- thickness’ of corneal tissue is transplanted, and 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 keratoconus can be very upsetting. It’s normal to find yourself worrying about the future and how you will cope. 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. It may even vary within the same day. 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 to make some things stand out. You’ll be more comfortable if your environment causes you minimal glare. This can involve the lighting around you and the devices you’re using.

You can find out tips for making the most of your sight by downloading our booklet:

Useful contacts

UK Keratoconus Self Help and Support Association is a registered charity that works to raise awareness of keratoconus. They can provide information, factsheets and peer support for people in the UK who are living with the condition.