Treatments & Surgery - Cataract Surgery and Glasses
Take Control of Your Eyesight
In cataract surgery it is normal for the lens of the eye, which contains the cataract, to be removed. This means a loss of focus which is then corrected by implantation of an intraocular lens (IOL). This is standard practice the world over. The eye is measured prior to surgery so that the “correct” IOL can be chosen.
So, what then, is the “correct” IOL?
Traditionally surgeons have recommended that an IOL be inserted to make the eye in focus for long distance, so that glasses are not generally required for, say, driving or TV viewing. This is the standard approach using monofocal IOL’s and for many people is very satisfactory. However, if both eyes are operated with such IOL's then reading glasses are inevitably required. Often, glasses are needed for computing as well. Again for many people this is quite acceptable.
There are some alternatives. One option is what is termed “monovision”. In this instance, one eye is corrected to be in focus for long distance, whilst the other eye is left somewhat short sighted so that it is only in focus for near vision, e.g. reading. So one eye does one task and the other eye the opposite task.
Does that sound strange? For suitable people this is a very useful solution and means that they are almost completely independent of glasses. However, there are some people who will not tolerate one eye being blurred and for them, monovision is not acceptable. Testing prior to surgery can usually sort out whether or not one is suitable for monovision.
Another option is the use of “multifocal” IOL's. Using tiny prisms embedded in the lens material these IOL’s allow some near vision whilst maintaining reasonably good long distance vision. There are some limitations to what can be achieved with these IOL’s. The overall quality of the distance vision is somewhat reduced compared to standard monofocal IOL's. Secondly, fine reading detail may still require the use of reading glasses. However, for many day to day activities, multifocal IOL’s provide a measure of spectacle independence. Some people are not suitable for multifocal IOL’s, especially those with macular degeneration and young people. Generally, both eyes would need to have the multifocal IOL.
Many people have what is called “astigmatism”. The eye is more the shape of a rugby ball rather than a soccer ball. Astigmatism affects vision clarity to varying extents. Small amounts of astigmatism can be corrected during cataract surgery by placing the surgical incision in specific locations. For larger amounts of astigmatism, correction can be achieved by the use of “toric” IOL’s. These premium IOL's have built in astigmatism correction and have to be very accurately placed within the eye to have the desired effect. This requires some special marking of the eye immediately prior to the operation. By using toric IOL’s many people with a lot of astigmatism can be much more independent of glasses than they would have been with ordinary monofocal IOL’s.
Some people have very high degrees of myopia (short sighted) or hypermetropia (long sighted) without cataract. In certain instances, when LASIK is not applicable, these errors can be corrected using the same techniques of cataract surgery and IOL implantation.
