Phakick Intraocular Lenses

Phakick intraocular lenses are a relatively new invention which are used to correct nearsightedness. These lenses are highly thin and can be permanently implanted into the eye in order to help reduce the need for glasses or contact lenses. The lenses themselves are made of plastic or silicone and Phakick refers to the fact that they are implanted into the eye without removing the natural lens of the eye. During the implantation surgery, a small incision is made in the front of the eye, the phakic lens is then inserted through this incision and placed either just in front of or behind the iris. Phakick lenses are mostly used to treat refractive errors, which are errors which occur in the eye's focusing power. The majority of Phakic lenses are currently used to treat myopia (nearsightedness). In those with normal vision the cornea and the lens of the eye focus light in order to create and image on the retina. This bending and focusing of light is known as refraction and problems in the focusing power of the eye, cause images which appear on the retina to be blurred or out of focus.

Those who are nearsighted have a lot more difficulty seeing objects at a distance as the images of distant objects come into focus in front of the retina. Phakic lenses cause any light which enters the eye to be focused on the retina which can help to provide much clearer vision at a distance without the use of glasses or contact lenses. Depending upon how nearsighted you are and several other factors, you may benefit from other types of surgery to correct your refractive errors such as PRK (Photorefractive Keratectomy) and LASIK (Laser Assisted In-Situ Keratomileusis).

The Procedure

Before going ahead with the procedure you will need to have an examination to make sure your eye is healthy and suitable for surgery. Your doctor will examine your medical history and test your eye health using a number of methods in a thorough examination of both eyes. These will include; measuring your pupils, the depth of your anterior chamber (which is the distance between your cornea and your iris) and the cells located on the back of your cornea, known as endothelial cells will be counted. If you wear contact lenses then you may be advised to stop wearing them before your examination so that the refraction and keratometry (a measure of how much your cornea curves) tests will be give accurate results. It's at this stage you should inform your doctor of any medications or vitamin supplements you are taking, any allergies, any eye or medical conditions and whether you have undergone any previous eye surgery.

A couple of weeks before surgery your doctor may schedule you for a laser iridotomy, this will prepare your eye for implantation of the lens. Before the procedure you are normally given eye drops in order to make the pupil smaller and to numb your eye. The doctor will firstly rest a large lens on your eye and will then make small holes in the outer edge of the iris (the coloured part of your eye) by using a laser. These holes are there to prevent a buildup of fluid and pressure in the back chamber of your eye after the implantation surgery begins. This procedure should only take a few minutes. After the iridotomy procedure, your surgeon will check your eye pressure and then you should be able to return home. Before the surgery itself you may be advised to stop wearing contact lenses for a few weeks. Similarly you may also be required to cease the use of certain medications that could increase the risk of bleeding during surgery. You may also be prescribed antibiotic drops to help protect against infection or anti-inflammatory drops to help prevent inflammation before surgery. It's also likely you'll be advised not to eat or drink anything on the day of surgery.

The surgery itself is performed under a local anaesthetic, meaning you will be awake throughout. You may be given a sedative or other medication in order to help you relax and to keep you comfortable. Your surgeon may inject some medication around the eye to numb it and another injection may be given to prevent you from being able to move your eye. Your eye and the surrounding area are then cleaned and a instrument is put in place to hold your eyelids open. Your surgeon will begin by making an incision in either your cornea, sclera (the white part of the eye) or the limbus (where the cornea and the sclera meet). Your surgeon will then place a lubricant onto your eye to help protect the rear of the cornea, where the endothelial cells are located, during the insertion of your phakick lens. The lens itself is inserted through the incision in the eye to the anterior chamber. Depending upon the specific type of lens it will be attached either to the front of the iris in the anterior chamber or behind the iris and in front of the lens in the posterior chamber. Your surgeon then removes the lubricant and, depending on what sort of incision is made, it may be closed up using tiny stitches. You will usually be given some more eye drops and ointment and then your eye will be covered with a patch or shield. The entire process takes around 30 minutes. You should be allowed to return home the same day and will be given antibiotic and anti-inflammatory prescriptions to help promote healing.

Aftercare

Immediately following the surgery you may find you are sensitive to light and may experience the sensation of a foreign object in your eye. Any discomfort you experience after the procedure should be minor but your surgeon may prescribe some pain medication to make you more comfortable during the first couple of days after surgery. It's normal to have regular followup visits with your doctor to monitor your progress and check your healing. You will need to take eye drops for a few weeks after surgery, as they will help decrease inflammation and help prevent against infection. You may be required to keep wearing the shield constantly or, in some cases, it can just be worn at night. The shield will help protect against eye rubbing or accidently putting too much pressure on the eye and also protects against accidental poking of the eye. Your vision will be blurred or hazy for a few days after surgery but you should notice improvements after about five days. It takes between two to four weeks for your vision to fully stabilise. In this period it's important that you don't rub your eyes. You may experience a sensitivity to glare or see halos around lights but these symptoms should steadily decrease as your eye heals.

The Risks

As with any other surgical procedure, the implantation of phakick lenses is not without risk. Although most implantations are performed safely, in some cases patients can experience severe vision loss which cannot be corrected by surgery. Although visual symptoms usually disappear as the eye heals, in some cases difficulty seeing at night, halos or double vision can stay for a longer amount of time and can even become permanent. If a complication occurs in the initial surgery then you may require an additional operation in order to reposition, replace or remove the phakick lens. While Phakic lenses are intended to remain in the eye permanently, they can be surgically removed. However there is no guarantee that you will return to the level of vision you had before the lenses and it may cause some damage to the eye. There is also a danger of being over or under-treated and a large proportion of treated patients don't achieve twenty-twenty vision after surgery. This can be due to the power of the implanted lens being too strong or too weak because of difficulties in determining what power lens you require. This can mean that even after surgery you may still require glasses or contact lenses. Other risks include a clouding of the cornea, developing a cataract or a retinal detachment. Infections, bleeding and severe inflammation can also occur but it's usual to be given eye drops to prevent against these.

Important notice