Implantable Collamer Lenses
The need for glasses can be reduced considerably or, in many cases, entirely by refractive laser eye surgery. There are some patients either with strong prescriptions (typically -8.00D and above; +4.00D and above), thin corneas or corneas at risk of warping (ectasia), where removing sufficient tissue is not possible. For these patients alternative techniques based around placing a lens inside the eye are more suitable. A number of different lens implants have been developed for correcting refractive errors. The Implantable Collamer Lens (ICL) is the safest of these.
The ICL is made from a soft biocompatible gel material based on natural collagen. Because the lens is implanted within the eye, no cleaning is required. The first ICL was implanted in 1993. Since then, over 30,000 ICLs have been implanted. 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 ICLs are an option that may be suitable alternative to laser surgery.
In high myopia (>-8.00D) the eye has too much focusing power. Without glasses, light from objects in the distance is focused in front of the retina, forming a blurred image. The ICL for high myopia (-8.00D and above) is a negative lens which acts to neutralise the excessive focussing power of the eye allowing clear vision in the distance.
The ICL for hypermetropia (+4.00D and above) 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).
ICL implantation can be performed under either general or local anaesthetic. The operation usually lasts 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. Your surgeon will talk you through this. You should stare straight up at the operating microscope light throughout the procedure. This will 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. 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.
80% of patients with no other eye problems are able to see 6/6 or 20/20 without glasses after ICL (or TCL) implantation at Moorfields Eye Hospital. 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.
After the operation
At the end of the procedure a plastic shield 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 eye may be relatively light sensitive in the first few days after surgery. Beyond this, any postoperative discomfort should be minimal.