Dr. Frikkie Hartog is an ophthalmologist in private practice, specialising in cataract and refractive surgery. He will discuss the very commonly performed cataract procedure as well as the questions often posed to him.
A cataract is the natural lens inside the eye that becomes progressively harder and cloudy with age. The natural lens is situated behind the color part, or iris, of the eye. Light entering the eye is transmitted through the central black pupil and then through the centre of the lens. Under ideal circumstances the lens will focus the incoming light on the retina at the back of the eye, permitting sharp focused vision. Unfortunately some need the assistance of spectacles though to improve their vision. There are three different spectacle errors, nearsightedness (myopia), farsightedness (hypermetropia) and astigmatism. In astigmatism the front of the eye is not round, but more resembles the shape of a rugby ball.
The second function of the lens is accommodation. In order to change the focus from distance to near, the lens changes shape, thereby refocusing the light for reading. As the lens becomes harder with age, this process also fails, and reading glasses becomes essential to permit clear vision for reading. This process is called presbyopia, and usually becomes significant in our forties. Presbyopia is an age related change that occurs in everyone, irrespective of your previous need for spectacles or not.
The common symptoms associated with cataracts are a decrease in vision, as well as an increasing dependence on spectacles, not only for reading, but also for computer work and distance vision i.e. for driving and reading the footnotes on the TV screen. Due to the cloudiness of the cataract lens, people will also some-times complain of halos around lights, poor vision in poor lighting conditions as well as oncoming traffic lights blinding them. A common complaint is that it seems as though their spectacle lenses are dirty.
A cataract is removed during a cataract procedure. During this procedure the cloudy natural lens is replaced with an artificial lens. The main aim of the proce-dure is to restore clear vision. With improvements in technology, the surgical pro-cedure as well as the concomitant artificial lens choices, the secondary aim of providing spectacle independence, has become very important. The cataract pro-cedure is performed under local anaesthetic, with a thin needle, through a small 2,2mm incision. The duration of the procedure is less than fifteen minutes and completely painless. Healing occurs very rapidly, and most patients perceive a significant improvement in their vision within a few days. The implanted artificial lens grows into its final position within a month, and never needs removal or re-placing. The visual result is also very stable and permanent. The patients vision is stable after the procedure. The natural lens is responsible for progressive specta-cle changes, but the artificial lens provides stability.
An artificial lens is always implanted during cataract surgery, otherwise a person can only see with very thick spectacles. For more than sixty years lenses have been implanted during a cataract procedure in order to restore a patients vision. As can be expected the technology has improved tremendously, and at present all four the spectacle errors or combinations thereof can be corrected with an arti-ficial lens. Spherical lenses correct for nearsightedness (myopia) as well as far-sightedness (hypermetropia). Astigmatism is corrected with toric lenses, and presbyopia is addressed with multifocal intra-ocular lenses.
In our daily functioning we need good vision at three distances. Good distance vision is essential for tasks like driving and watching TV. Near vision is very im-portant for reading, but we also need good intermediate vision at arms length. Intermediate vision is required for many of our daily tasks like seeing your face in the mirror, reading on a cellphone or tablet and common tasks like preparing food. Since 2012 the new trifocal multifocal lenses have become available, and they are able to correct a patients vision for all three distances. The trifocal lenses are very effective in providing complete spectacle independence. Dr. Frikkie Har-tog reports that his experience with these lenses confirm the international report that approximately 95% of patients will be completely spectacle independent after the implantation of these lenses. Some patients still do occasionally need thin reading glasses, especially in poor lighting environments.
The lens best suited to each individual will vary, and best need to be discussed with your ophthalmologist.
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