How keratoconus affects your vision

When you have keratoconus, your vision becomes blurred. This is because the front of your eye is not completely smooth and round. This affects the focus of your eye causing short sight (myopia) and astigmatism, in which the light that passes through your eye forms an unclear image at the back of the eye. In advanced stages of keratoconus, some patients develop scarring in the cornea, which makes their sight blurred by reducing te amount of light which can enter the eye. A small number of patients may experience a sudden, painful loss of vision if fluid from the eye enters a very thin cornea. This is called hydrops and will settle with time.

What causes keratoconus?

We do not know exactly what causes keratoconus. It may be partly genetic (passed on in a family through the genes) and it happens more in people who have allergies like asthma or eczema. There may also be a link between keratoconus and people who rub their eyes frequently.

Who can get keratoconus?

Keratoconus is usually diagnosed in young people at puberty, late teens or early twenties. It is more common in non-caucasians and affects up to 1 in 450 people (depending on ethnicity).

How can the ophthalmologist tell if I have keratoconus?

The eye doctor (ophthalmologist) or optometrist (ophthalmic optician) will examine your eyes with a microscope called a slit-lamp. You might also have a corneal topography scan (pentacam). This is a quick, painless photo which checks the shape and thickness of your cornea in detail.

What treatment is available for keratoconus?

There is no cure for keratoconus and it cannot be treated with eye drops or medication.

In the early stages, some patients will simply need glasses to see well, but many patients eventually require contact lenses for better vision. The contact lenses are usually small, hard lenses (rigid gas permeable lenses) but some people may wear soft (hydrogel) lenses and some need special lenses made specifically for keratoconus eyes. Contact lenses do not made the condition worse of better, they just improve your vision while you are wearing them. In very advanced cases, where contact lenses fail to improve vision, a corneal transplant (‘graft’) may be needed. Most patients with keratoconus will not need a corneal transplant.

Corneal collagen cross-linking (CXL)

CXL is a new treatment that can stop keratoconus getting worse. Also known as C3R, it uses ultraviolet light and vitamin B2 (riboflavin) drops to stiffen (and strengthen) the cornea. It is effective in over 90% of patients with a single 30-minute outpatient procedure. It is only suitable for some people with progressive keratoconus. As with all operations there are risks: CXL is safe, but there is a small chance of worse vision afterwards. Because it is a new treatment, we do not know the long term effects for sure, although we believe the risks of any unexpected long-term side effects are very low.

What is cross-linking?

Keratoconus gets worse because the cornea weakens. CXL uses ultraviolet light and vitamin B2 to stiffen the cornea which used together cause fibers within the cornea to cross link or bond more tightly. This treatment mimics the normal age-related stiffening of the cornea, which is known a natural cross-linking.

Which patients benefit from CXL?

The treatment is recommended only for patients whose corneal shape scans show that their keratoconus is getting worse, or for those who are at particularly high risk of worsening keratoconus. It usually stops getting worse by age mid 30s due to natural age-related cross-linking so CXL is not normally required for older patients.

What to expect from cross-linking

We will only ever operate on one eye at a time (not both together in the same procedure).

The procedure is conducted in the Day Surgery Unit at The General Hospital and takes approximately 30 minutes.

Anaesthetic drops are used to numb the surface of the eye, and a soft bandage lens is placed over the eye at the end of the procedure.

The anaesthetic drops will wear off later on the day of the procedure and your eye will be gritty, red, and sensitive to light for several days. Sunglasses can help with this.

After treatment, you will still need to wear spectacles or contact lenses. Your eye will be sore for about a week post operatively, and over the counter pain killers like paracetamol can help with this.

Although the vision can be hazy, most patients can resume contact lens wear after a week or two, and return to work after a week

You should allow at least one week off from work or studies. Day to day activities like watching TV or using a computer will not damage your eye.

It is important to put the eye drops in regularly as prescribed. Wash and shower normally, but try to avoid getting water in your eyes.

You may exercise but should not swim till the surface of the eye has healed.

Post operative management

· Mr Spiteri will give you preservative free drops (Chloramphenicol & Dexamethasone) to use 4 times per day. Use them 5 minutes apart so as not to wash them out.

· You will also be given spare bandage contact lenses, and preservative free Proxymetacaine anaesthetic drops to be used if necessary.

· Finally, you will be given preservative free Hypromellose drops to be used hourly (a lubricating drop)

What are the risks of CXL?

In general, CXL is very safe but like all operations, your eye needs time to heal and problems do occasionally occur. As with all procedures, there is a small chance (about 1 in 30) of worse vision afterwards. Without CXL treatment, at least 20% of patients with keratoconus will eventually require a corneal transplant.