Intra Ocular Lens Implants

For a minority of patients an intraocular lens implant may be the most appropriate solution for vision enhancement as not everyone is eligible for laser vision correction. This may either be because of extreme refractive error (short sight, long sight and/or astigmatism), unusual corneal findings or other eye health concerns (e.g. cataract).

For such patients another good alternative to laser vision correction is the option of surgically implanting an Intra Ocular Lens (IOL) inside the eye to improve vision in order to reduce dependence on glasses and/or contact lenses.

Inevitably, for some patients there may be some overlap as to whether a laser procedure or implantation of an intra ocular lens inside the eye is the method of choice. Our highly experienced team will advise at the time of consultation.

These lenses are known as phakic intraocular lenses or anterior chamber intraocular lenses. The lens is inserted into the anterior chamber of the eye (in front of the iris) and the natural lens within the eye is not disturbed. These procedures are sometimes appropriate for patients who require an implant and where there is no need to remove the natural lens from the eye.

Refractive treatments (to reduce dependency on spectacles) are elective procedures and are not covered by private medical insurance. If you are considering having a procedure for cataracts, your insurer may be willing to pay for part of the cost of your procedure. Each insurer is different however, so it is important that you speak to them before you commence your treatment.

An Intra Ocular Lens (IOL) is simply a small, artificial lens implanted inside the eye to correct focusing errors. There are two different types of lens implants procedures. The natural crystalline lens inside the eye can be replaced with an IOL (refractive lens exchange) or an additional lens can be implanted into the eye (anterior IOL).

As with all procedures, extensive diagnostic testing and planning is required before treatment can commence. Consultation will be performed by a combination of skilled optometrists and Consultant Ophthalmic surgeon. If you elect for treatment, an interval of approximately 4-6 weeks is required in order to receive the custom made lenses to the correct specification. The procedure is performed in a specialist, sterile theatre and takes about 20 minutes. A local anaesthetic injection and anaesthetic drops are used to numb the eye. You will not therefore feel any pain. Drops to constrict the pupil are also used. A small incision is made at the edge of the cornea through which the ARTISAN lens is inserted and then carefully clipped to the iris tissue. Sutures are used to close the wound. After intraocular lens treatment you are able to go home but it is essential that you are accompanied. The treated eye will be patched and you will be given instructions for use of eye drops to prevent infection and help healing. You should notice improvement in your vision by the next day, although the final optical outcome will settle further with time. An appointment will be made for one week after treatment when specific aftercare schedules are decided. You should be able to drive and return back to work within a few days of the procedure. Bear in mind however, that your vision will be unbalanced during the interval between the treatment of each eye. Over the past few years the ARTIFLEX lens has been developed from an earlier lens design called ARTISAN. ARTIFLEX lenses are made from a combination of an ultraviolet absorbing Polysiloxane optic, and rigid haptics (the part that attaches the lens to the iris) made from Perspex CQ UV (polymethylmethacrylate - PMMA). These lenses can be used to correct myopia (from -2D to -14.5D). The potential advantage of using a flexible lens is that it can be inserted through a much smaller incision and therefore better control post-op astigmatism. Further details of the ARTISAN/ARTIFLEX lens can be found by visiting their website.

Over the past few years intraocular 'implantable collamer lenses' have been available. STAAR Implantable Collamer Lenses are made partly from collagen - the fibre that is the basic building block of the eye. At present, there is only fairly short-term follow-up data available on patients who have had these lenses inserted, but the biocompatibilty of the Implantable Collamer Lenses (ICL) seems good. Implantable Collamer Lenses can be used to correct both short-sight (from -3D to -18D) and long-sight (from +1.5D to +18 D). A new toric Implantable Collamer Lenses (ICL) to correct astigmatism has recently been introduced. Unlike the Artisan lens, the STAAR Implantable Collamer Lenses (ICL) is placed into the eye via a very small incision at the edge of the cornea and is then positioned behind the iris and in front of the natural crystalline lens of the eye. The insertion of the Implantable Collamer Lenses (ICL) is also generally carried out under local anaesthetic. Drops are put into the eye to dilate the pupil and anaesthetise the cornea. A small incision (3mm) is made at the edge of the cornea and the Implantable Collamer Lenses (ICL) is injected into the eye and carefully placed over the natural lens. A drug solution is then injected into the eye to constrict the pupil. After the operation antibiotic drops are given to help prevent infection and steroid drops to suppress inflammation. Visual recovery is rapid, with functional vision virtually straight away and stabilisation of refraction within a few weeks.

In this procedure the natural crystalline lens is replaced with an implanted contact lens of appropriate power. The procedure is commonly referred to as Refractive Lens Exchange (RLE) or Clear Lens Exchange (CLE). It is essentially the same procedure as routinely performed the world over for Cataracts, where the natural crystalline lens becomes cloudy and reduces visual performance.

To calculate the correct power of the intraocular lens implant, it is necessary to make measurements of the eyes preoperatively, including an assessment of the length of the eye by either ultrasonic biometry or laser interferometry (IOL Master). This information allows the surgeon to predict with a fair degree of accuracy what the final optical state of the eye will be. The surgeon can then discuss the possibilities of the various optical outcomes from the surgery with the patient, and select an appropriate lens to achieve the desired result.

The majority of lens implants used are of fixed focus (monofocal), but there are also multifocal implants which give vision for both distant and near objects. However, if monofocal lenses are implanted in both eyes with one eye left a little short-sighted, a similar range of vision can be achieved. In people who have a significant amount of astigmatism, special toric (aspherical) intraocular lenses may be required to achieve the desired optical outcome, or incisions can be made in the cornea at the time of surgery in order to reduce the astigmatism (astigmatic keratotomy). Alternatively the surgery can be followed by laser surgery to the cornea (e.g. lasik), to correct the astigmatism.

Clear lens extraction surgery can be carried out with local anaesthetic. Drops are used to anaesthetise the eye and injections made beside the eye, to stop the eyelid and eye moving during the surgery. Since local anaesthetic has little effect on the patient's general condition, they are fit to return home shortly after the procedure, and an in-patient hospital stay is not usually necessary. Alternatively the surgery can be carried out under a general anaesthetic.

The natural lens of the eye has a diameter of around 12mm, so if it is to be taken out in one piece, the incision into the eye must be at least this long. When a large wound is created in the eye, there is almost always distortion of the corneal shape during the wound healing process and this creates optical distortion - astigmatism - which then requires spectacle correction. To overcome this problem it is preferable to break up the lens inside the eye and then remove the lens matter a little at a time through a small incision. The phakoemulsification instrument has a small probe connected to an ultrasonic transducer. The ultrasonic vibrations fragment the lens matter and the emulsified fragments are then aspirated in a flow of saline solution. Once the lens matter has been removed the intraocular lens implant is introduced through the same small incision. Made from deformable plastic, the implant is rolled or folded up and injected into the eye. Inside the capsular membrane (remnants of the natural lens), the lens implant unfolds and its optical part is held centrally behind the pupil by supporting loops or plates (haptics).

In the majority of cases lens extraction has a favourable outcome. Sometimes other eye conditions such as glaucoma or macular degeneration may limit the quality of the visual outcome. Very rarely the surgery may be complicated by problems such as inflammation or infection. Occasionally the function of the retina can be impaired by the lens extraction surgery - for example central visual function may be permanently impaired by leakage of fluid into the retinal tissue (cystoid macular oedema). Lens extraction surgery can lead to the vitreous jelly breaking away from the back of the eye (posterior vitreous detachment), with an increase of 'floaters' in the vision. A proportion of patients suffering posterior vitreous detachment go on to develop retinal detachment, which if left untreated can cause irreversible visual loss. High myopes are at increased risk of vitreous and retinal detachment anyway, and there is no doubt that lens extraction is associated with an increased incidence of these problems post-operatively. Treatment planning and recovery is similar to that described in the earlier section on phakic IOLs.

In phakoemulsification surgery 98% of the lens is removed, leaving only the outer lens capsular membrane. This membrane is used to support the intraocular lens implant. After some time, usually some years, the lens capsule can become hazy in around 30% of patients. When the problem arises it is simply remedied by the use of a YAG laser. This invisible infra-red laser beam is focused on to the capsular membrane and vaporises the tissue - so clearing the optical path for light rays to reach the back of the eye. A YAG capsulotomy takes only a few minutes to perform, is entirely painless, and ensures that the visual pathway remains clear of capsular membrane indefinitely.