Corneal Cross-linking

What is keratoconus?

Keratoconus means "conical or cone-shaped cornea". It is a condition where the cornea (the clear window on the front of the eye) becomes stretched and thin and begins to bulge into a cone-like shape. The cornea is the major focusing surface of the eye, so keratoconus causes blurred and distorted vision. In keratoconus the normal physical properties of the cornea are altered, and this causes refractive error, usually short-sightedness (myopia) and irregular high astigmatism. It usually affects both eyes, but sometimes one eye may be badly affected whilst the other eye shows very little sign of the condition.

What is corneal cross-linking?

Developed in Switzerland and Germany in 1998, corneal collagen cross-linking uses ultraviolet light and riboflavin eye drops (vitamin B2) to stiffen the cornea. It works by cross- linking the collagen fibres in the cornea to each other and within themselves. This procedure has been carried out in early stages of keratoconus as a way of halting its progression. It is often used in combination with intracorneal ring implantation (kerarings), or to treat post-LASIK ectasia. Collagen cross-linking mimics the corneal stiffening which occurs naturally with ageing. This is the reason why keratoconus does not usually progress in people aged 50 and over.

Corneal cross-linking (CXL) is the only treatment currently available which appears to stop progression of keratoconus. Its purpose is not necessarily to improve the vision – this is done by the use of spectacles or contact lenses after treatment. Evidence from three randomised clinical trials one year after CXL showed success in halting keratoconus progression in over 90% of treated eyes, with over 45% of eyes also gaining an improvement in corneal shape. Longer-term results (up to five years) from a different study suggest a similarly high success rate in preventing keratoconus progression.

The procedure

Mr Wilkins performs a rapid version of ‘epithelium-off’CXL, which is an up-to-date, and potentially safer, variation of standard CXL. Standard CXL involves 30 minutes of ultraviolet (UV) light treatment. Rapid CXL speeds this process up, by delivering the same total amount of UV light energy in eight minutes.

You will be given eye drops to use after the procedure. The soft ‘bandage’ contact lens will remain in your eye until the surface has healed (about seven days). If the bandage lens falls out during this time, please throw it away – do not attempt to reinsert it. The anaesthetic drops applied during surgery will wear off later on the day of your procedure, and your eye will be gritty, red and sensitive to light for several days. Everyone’s experience of pain is different, with some patients reporting very little discomfort and others describing the first few days as very painful. Wearing sunglasses helps alleviate light-sensitivity. Your vision will be quite blurred at first, but will clear gradually over the first few weeks.

If you experience increasing pain three of four days after your procedure, please visit A&E to check for infection. Infection is relatively rare, affecting fewer than 1% of patients.

Activity limitations

  • You should allow at least one week off while most of the surface healing occurs, or two weeks if your job involves a lot of computer work, and the treatment is being done on your best eye. You will be putting eye drops in every hour for the first day, and then every four hours for the following days. Using your eye soon after surgery – for example, to read, watch TV or use a computer – will not do any damage, but you might find it more comfortable to rest with your eyes closed early on.
  • Dusty environments are unlikely to damage the eye, but may be irritating, and should be avoided for 2 weeks after surgery. If you get dust, dirt or an eyelash in your eye, wash out with an eye drop.
  •  Do not rub your eyes after the procedure. Eye rubbing may cause progression of keratoconus and should be avoided in all circumstances. Put an artificial tear drop (the   lubricant prescribed on the day) into the eye if feels itchy or irritated.
  • For the first week:
    • Please refrain from running, aerobics or gymnasium (in case of injury or sweat running into the eyes) or any racquet/batting sports.
    •  Do not use eye make-up.
    • Try not to get water or shampoo in your eyes in the shower or when washing your face (dab very gently with towel if you do).
    •  It is a strongly advised that you do not fly any long haul flights within the first week.
  • For the first 2 to 4 weeks :
    • you should not swim in chlorinated water, play rugby, scuba dive or practice any type of martial arts or contact sports (boxing, kick-boxing) where there may be a direct blow to the eye. Chlorinated pools can irritate the eyes and public pools are commonly contaminated. Wear goggles when swimming (once allotted healing time is complete).

You will be given an appointment the following week to check your eye is healing properly. You may drive when you can read a number plate at 20 meters with both eyes open while wearing glasses or contact lenses as appropriate; we will check your vision in the clinic the week after your procedure to confirm if your vision is good enough to drive. It is normally safe to resume contact lens wear once the eye surface skin layer has healed. This typically happens around the end of the second week after your procedure.

Am I suitable?

Cross-linking is usually offered to those who are under 35 whose keratoconus is changing. The way that we see these changes is through analysis of the patient’s current and previous prescriptions and the scans carried out during the consultation. Occsasionally, patients under 18 may be treated at the time of diagnosis to prevent worsening of vision. Patients who are 35 and over tend to have stabilised keratoconus and are therefore offered other treatment options including intracorneal ring segments, corneal graft and contact lenses or spectacles.