For some patients, either with strong prescriptions, thin corneas or corneas at risk of warping (ectasia), removing sufficient tissue is not possible. In such cases, alternative techniques to refractive laser eye surgery, based around placing a lens inside the eye, are more suitable. Several different lens implants have been developed for correcting refractive errors, the safest of which is an implantable collamer lens (ICL).
WHAT IS AN IMPLANTABLE COLLAMER LENS (ICL)?
The first implantable collamer lens (ICL) was implanted in 1993 and, since then, over 30,000 ICLs have been implanted. The ICL is made from a soft biocompatible gel material based on natural collagen. The lens is implanted within the eye so no cleaning is required. ICLs do not cause discomfort and are not visible in the eye.
AM I SUITABLE?
If your prescription is above -8.00D for myopia and above +4.0D for hypermetropia, then an implantable collamer lens may offer a suitable alternative to laser surgery:
A high myopia (-8.00D and above) ICL is a negative lens that acts to neutralise the excessive focussing power of the eye allowing clear vision in the distance.
A hypermetropia (+4.00D and above) ICL does the reverse. It is a positive lens that acts to neutralise insufficient focussing power.
Astigmatism (uneven focusing power) can also be corrected using the toric ICL (TCL).
Implantable collamer lens (ICL) implantation can be performed under either general or local anaesthetic and usually takes around 30 minutes. The surgeon will switch on a bright operating microscope light. This may be very dazzling at first, and it is often helpful to look away for 30 seconds before looking straight up into the light. You should stare straight up at the operating microscope light throughout the procedure to keep the eye in the ideal position for the surgery. Blinking is no problem but it is helpful to keep both eyes open between blinks.
Some movement is normal, and will not be a problem for the surgeon but excessive movement will tend to slow the procedure down. The surgeon may elect to freeze the muscles around the eye, in addition to numbing the eye surface, in order to complete the operation. This is achieved with an injection of anaesthetic behind the eye. Although this may sound difficult, it is usually straightforward and pain-free. Many surgeons and anaesthetists administer these muscle blocks in all their patients.
AFTER THE OPERATION
Following ICL (or TCL) implantation at Moorfields Eye Hospital, 80% of patients with no other eye problems are able to see 6/6 or 20/20 without glasses. Over 95% are able to see at the driving standard or better, and simple enhancement procedures are available for many patients who are not initially at this level. The quality of vision for most patients is similar to that obtained in contact lenses. For patients with significant astigmatism, it is often better. TCLs provide better stability of vision than soft toric contact lenses.
At the end of the procedure a plastic shield is placed over the eye. This protective shield is normally worn for the journey home and during sleep for the first 7 days after surgery. Visual recovery after ICL implantation is rapid. Patients can commonly see at the driving standard or better within 2 days of surgery. Mild gritty discomfort is normal, and the eye may be relatively light sensitive in the first few days after surgery. Beyond this, any postoperative discomfort should be minimal.
Moorfields Private Outpatients Centre
9-11 Bath Street
King Edward VII Hospital
5-10 Beaumont St, Marylebone, London
T:0207 566 2603
M:07831 919 634