In our forties we start to experience difficulty in reading. This occurs due to changes that occur in the natural lens of the eye. With age the lens becomes hard, and cannot change shape any more in order to change the focus of the eye from distance to near.  This is called presbyopia and is a consequence of age, irrespective of our spectacle use. The experience is usually that the arms are getting too short to read clearly. The natural progression means that we get progressively more dependent on spectacles, not only to read, but also for computer work or reading the paper. When the lens fails us altogether, we also experience difficulty with our distance vision. It becomes difficult to read the print on the TV, or the writing on road signs.

This process is known as Dysfunctional Lens Syndrome.

Multifocal intra-ocular lenses provide a permanent solution. The newest trifocal lens replacements have been available since 2012, and permit sharp vision at three distances without the help of spectacles. The first focal point is distance for watching TV and driving. Intermediate vision is required for many daily tasks, including work on the computer, reading on a cellphone or tablet, as well as seeing your face in the mirror. Near vision is corrected at 45 cm in order to be able to read small print. The intermediate distance is important, and the distance varies with different intra-ocular lenses. Some lenses provide vision at 80 to 90 cm, but this is not functional and at arms length. The more functional distance is 60 cm, and only provided by some multifocal intra-ocular lenses.

The success of multifocal lens replacements are excellent. Approximately 95% of patients are completely spectacle independent after the implantation of multifocal lenses. The rest might sometimes need thin spectacles, for instance a reader might be needed in poor lighting conditions. It does take some time to adapt to the lenses, just like any new spectacles. Some individuals are completely spectacle independent after a week, but for most it will take two to three months before they are comfortable at all distances. The most common experience reported by patients is some difficulty on either the computer or reading, but this improves very quickly.

It is important to note that the result of a refractive lens replacement (otherwise known as refractive lens exchange) and cataract surgery is permanent: the patients’ vision will not change significantly in the future. The patients vision changed because of his own lens becoming harder and cataracts with age. The implanted lens is made from an acrylic plastic and is fixed in its final position four weeks after the procedure. The shape of the eye might change a little in future, but the change in vision is insignificant.

Intra-ocular lenses (IOL): choices

Multifocal intra-ocular lenses provides the ideal solution for most patients to provide complete spectacle independence. The technology has improved tremendously, and Dr. Hartog uses the latest trifocal intra-ocular lenses. A trifocal lens is very effective in providing spectacle independence, since it can focus at the three distances we need for our daily tasks. We need good distance vision for driving and watching TV. Intermediate vision is important for most of our daily tasks, like computer work, as well as seeing well on the cellphone, whereas near vision is important for reading. Trifocal intra-ocular lenses correct your vision at all three distances, thereby permitting very good functioning without the need for spectacles.

There are an increasing number of multifocal intra-ocular lenses available. This is partly driven by the demand from patients, but also by the success of the newer generation of lenses. All lenses are not equal in their functioning and success in providing spectacle independence though. This is why it is very important to receive adequate guidance from your ophthalmologist. Despite all the available choices for lens replacements, it is important to note that we all have very similar expectations and requirements: we need good distance, intermediate and near vision. It is also to consider the distance at which the lenses permit good vision, especially so for intermediate vision. We need good vision at approximately 60cm in order to see well on the PC, cellphone or read the paper. Only specific lenses can provide this, and therefore again the choice of multifocal lens is very important.

The trifocal intra-ocular lenses does not resemble multifocal spectacle lenses, or multifocal contact lenses. Multifocal spectacle lenses change in power from the top to the bottom. The stronger area at the bottom permits reading, but poses problems seeing obstructions at floor level while walking. Multifocal contact lenses differ in that one contact lens corrects distance vision and the other one reading, with some overlap.

The trifocal intra-ocular lenses work in all areas of gaze due to small rings that help to focus the light at three distances. The lens permits good distance, intermediate as well as near vision. The rings are the cause of small rings around lights, called halos. This phenomena occurs at night, when patients report fine rings around lights that disappears as the light gets closer when driving. The reason for this is the fact that the pupils of our eyes get bigger in poor light conditions to permit more light to enter the eye. The light entering from the side is poorly focussed though, and this causes halos and glare. We are not nocturnal animals by design.

Dr. Hartog always endeavours to provide reduced dependency on spectacles for all his patients. In instances where multifocal intra-ocular lenses are not an option for a patient, he utilises increased depth of focus lenses with planned mini-monovision. With this procedure most individuals only occasionally need spectacles for small print. The lens has an elongated focus point, and by planning for a small difference between the two eyes, the visual overlap provides excellent vision at different distances.


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