What are phakic lenses and what types are available?
Phakic intraocular lenses are intraocular lenses which are not inserted to replace crystalline lens but in addition to it. According to the type used, they are either anchored to the iris (anterior chamber) or between the iris and the crystalline lens (ciliary sulcus).
There are currently two types of phakic lenses available: the VISIAN ICL lens or the VERISYSE lens.
The Visian ICL (Implantable Collamer Lens) is a lens made from a flexible material called collamer, which is biocompatible with the eyeball. The foldable nature of this lens simplifies the surgical procedure, as very small corneal incisions are made. It is sold by STAAR Surgical and is placed in the posterior chamber of the eye, directly behind the iris. As a result, it is not visible to the naked eye, and can only be detected by a professional using a slit lamp. This type of lens can be used to treat myopia, hypermetropia and astigmatism.
The Verisyse lens, on the other hand, is made from a more rigid material, called PMMA (polymethyl methacrylate). Also available is the Veriflex lens, a flexible version, made from a material called Polysiloxane which allows for smaller corneal incisions to be made. Both are implanted into the anterior chamber and anchored to the iris.
Apparently it is possible to see that patients treated with Verisyse or Veriflex are wearing a lens in the anterior part of the eye, but this is barely noticeable. This lens can be used to treat myopia and astigmatism.
What does the procedure involve? Is it safe? What can you expect from phakic intraocular lenses?
BEFORE THE OPERATION:
If you are a contact lens user, you should stop wearing your lenses at least a week before the pre-operative visual assessment. Contact lenses can modify the curvature of the cornea and it is essential for it to return to its natural state to avoid refraction or calculation errors.
The surgeon may make an appointment for you one or two weeks before surgery to perform iridotomy using a YAG laser. This is only for patients who want to have their hypermetropia treated with ICL, as a preventive measure. This involves creating a small opening at the edge of the iris to allow the aqueous humour to circulate correctly. This is done with a view to preventing a potential increase in intraocular pressure (IOP) after the surgery. This procedure is performed during the appointment with your ophthalmologist, and is quick and painless. Today, there is an ICL lens version called “AquaFlow”, which is considered a major advance in the intraocular lens market as it avoids the need to perform iridotomy on patients who want to be treated for myopia and astigmatism. It ensures that the IOP remains stable and the constant exchange of aqueous humour between the ocular media also considerably reduces the risk of developing a secondary cataract. As a precaution, an iridotomy should still be performed on patients suffering from hypermetropia.
ON THE DAY OF THE OPERATION:
The procedure with phakic lenses takes around 10 minutes in the hands of an experienced surgeon and the patient must be accompanied by a trusted acquaintance, as they should not drive or travel alone after the operation.
Firstly, drops are applied to anaesthetise the eye and alleviate any discomfort during the procedure. In some cases, sedatives can be used to aid relaxation.
Corneal incisions are then made. The length of the incision is 6 mm for a Verisyse lens and 3.2 mm for Veriflex. With Visian ICL the incision is smaller, at just 2.8 mm.
Verisyse and Veriflex lenses are placed in the anterior chamber of the eye, whereas the Visian ICL lens is placed in the posterior chamber, between the iris and the crystalline lens. Once inserted, the lens unfolds inside the eye. Corneal stitches are only required with Verisyse lens treatment.
Finally, in some cases an eye patch is applied which must be worn for one or two days after the procedure. The surgeon will prescribe antibiotic and anti-inflammatory drops to be administered at home on the days following the surgery.
AFTER THE OPERATION:
Patients notice an immediate improvement in vision after the procedure with phakic lenses. Having said that, they may find their vision slightly cloudy or blurry and even experience an increase in sensitivity to light on the first few days after the operation. It can sometimes take two to four weeks for vision to become stable. In general, recovery with the Visian ICL lens is quicker than with Verisyse. Discomfort is usually minimal during the post-operative period, although you may sometimes experience dry eye or foreign body sensation.
An initial follow-up visit is required on the day after the operation. It is also essential to follow the instructions given to you by the surgeon regarding eye care and be strict with the medication prescribed. Ensure to attend scheduled medical checks to avoid any complications. Do not rub the eye, lift heavy objects or participate in physical activities until the eye is fully healed.
In general, most people can return to daily life immediately provided that they are cautious and follow all the instructions given by the ophthalmologist.
Are you a candidate for this intraocular implant technique?
Candidates for phakic lens implants are people who would like to stop using spectacles, enjoy optimum quality of vision and who, for some reason, cannot or do not want to have laser surgery. The lens is designed to remain in the eye indefinitely.
What happens if a cataract appears after I have a phakic intraocular lens implanted?
No problem. The great advantage of this technique is that it is totally reversible. The lens can be explanted through an equally simple procedure as that used to implant it. This allows for normal cataract surgery to be performed, where the crystalline lens is replaced with another intraocular lens.
It is important to stress that laser surgery is not reversible and that it also permanently modifies the shape of the cornea.
Do not hesitate to ask your specialised ophthalmologist to perform a full assessment and provide you with more information. This will enable them to recommend the best option for you.