During the mid-90’s, a revolutionary concept was introduced into the field of refractive surgery. Image formation within the eye mainly occurs by means of the corneaThe cornea is the clear, transparent 'front window' of the eye through which light enters the eye. It handles about two-thirds of the focusing power of the eye and is critical for good vision. See Info on Eyes – Anatomy. and the crystalline lensThe lens fulfils the same role as the lens in a camera. It handles about one-third of the focusing power of the eye and is critical for good vision.See Info on Eyes – Anatomy.. Initially, the cornea received all the attention to surgically modify the refractive power of the eye. During the late 1980's, two pioneers in ophthalmology, Dr's Jan Worst from The Netherlands, and Fyodorov from Russia worked independently on a concept to modify the refractive power of the eye by implanting extra lens power into the eye. Since then, others also followed, and currently there are a number of different lenses and lens designs on the market available for implantation.
These lenses are divided into two broad categories - the anterior chamberThe anterior chamber is the section in the eye between the cornea and the lens. See Info on Eyes – Anatomy. and posterior chamberThe posterior chamber is the section between the lens and the retina, which is filled with a jelly-like substance called the vitreous body. See Info on Eyes – Anatomy. lenses. These names indicate the location at which the lenses are placed. The two most popular anterior chamber lens designs are the ArtisanARTISAN® intra-ocular lenses represent a specific design of intra-ocular lens where the lens is fixed to the iris to correct severe refractive errors of the eye, or aphakia after cataract removal.™ and ArtiflexARTIFLEX® Phakic Intra-ocular lenses are used to correct myopia, hyperopia and Astigmatism. An Artiflex lens is foldable and is implanted through a small self-sealing incision of 3.2 mm.™ iris claw lenses, designed by Dr Worst. Only one successful posterior chamber lens is currently available, the STAAR ICLThe STAAR ICL (Implantable Contact Lens) is a custom-made phakic lens and one of the latest technological advancements to correct vision. See Other Options – Phakic Lenses.™. Various clinical criteria provide guidelines on the selection of the proper lens for implantation. Dr Potgieter was one of the very first ophthalmic surgeons in South Africa to perform phakic lens implantations during 1997 and has experience with all these lens designs.
A phakic intraocular lens is indicated for those cases where the refractive error is beyond the realm of other modalities.
Scope of correction:
- Short-sightedness (myopiamyopia is also known as nearsightedness. It results from an eye that is larger in size compared to a normal sized eye and/or a cornea that is relatively too steep, causing the image to focus in front of the retina instead of on the retina itself. See Info on Eyes, Optics and Refractive Errors - myopia.): up to -25.0 diopter
- Far-sightedness (hyperopiahyperopia is also known as farsightedness. It results from an eye that is smaller compared to a normal sized eye and/or a cornea that is relatively too flat, causing the image to focus behind the retina instead of on the retina. See Info on Eyes, Optics and Refractive Errors - hyperopia.): up to +15.0 diopter
- astigmatismAstigmatism is a condition caused by a cornea that has more than one curvature, similar to a rugby ball. The same image, therefore, focuses on multiple points in front of, on and/or behind the cornea, creating multiple and ghost images. Astigmatism may also be found in association with either myopia or hyperopia, which complicates the condition substantially. See Info on Eyes, Optics and Refractive Errors - Astigmatism.: up to -7.5 diopter
- Combinations of astigmatism and hyperopia/myopia
These refractive errors fall outside the range of laser or alternative corneal technologies, as this will result in extremely poor quality of vision.
As can be seen from the above values, this type of surgery is for really blind patients! The good news is that it is possible to treat these patients, and also that this type of procedure is frequently covered by medical schemes, depending on their internal rules.
Advantages of Phakic lenses
- In contrast to other refractive techniques, very high degrees of astigmatism, near sightedness and farsightedness can be corrected.
- The procedure is fully reversible. The lens may be removed at a later stage, replaced or changed if the prescription changes.
- The cornea, which is the most important refractive component of the eye, remains intact. There are consequently no permanent changes to the actual structure of the eye.
- In the past there was a risk that a cataractA cataract forms when the natural lens in the eye is, or is starting to become, opaque. If not treated, it can lead to blindness, which in most cases can be treated. See Cataract Centre – Understanding Cataracts. could form. New techniques reduced the risk substantially but, should it nevertheless occur, it can be treated.
Disadvantages of Phakic lenses
- Since this is a very delicate intervention, we prefer to treat patients under general anaesthetic. This gives Dr Potgieter full control over what happens during the surgery, so that there may not be any unexpected movement by the patient, compromising the surgery. We believe that this approach is part of the reason why we have seen very favourable outcomes since 1997.
- As this is an intraocular procedure, there is a small risk of infection. Worldwide statistics show an average infection rate of 0.025% or 1 in 4,000 cases for any intra-ocular procedure. We do, therefore, take extensive precautions against infection by doing the operation in a sterile environment, and provide detailed instructions for after-care to the patient. To date, over more than a 15 year period, we have not had an infection in one of our patients.
- Due to the mechanics of fluid distribution within the eye, the pressure within the eye may rise shortly after the procedure if the lens is not in perfect position. For this reason, we always keep our patients for an hour or two for observation after the procedure, so that we may react promptly upon any sign of pressure increase. During this time, you may relax in our company, and enjoy a cup of tea and sandwiches, or just doze off after the anaesthetic.
- Phakic lenses are relatively expensive, since these lenses are made to the patient’s prescription.
- These lenses may only be ordered upon a written approval from your medical scheme stating that they will cover the expense, or otherwise you may make a deposit to the value of the lens to guarantee its order. Once we receive such confirmation, it may still take up to 3 months for the lens to be manufactured and delivered, as it comes either from The Netherlands or from Switzerland, depending on the type of lens we are going to use.