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Multifocal and Toric implants

Traditional cataract surgery involves replacing the cloudy lens within the eye with a clear plastic lens or implant (see section on cataract). This is a very successful operation which usually returns the vision back to normal. For people who were significantly long or short sighted prior to the surgery; this is usually taken into account and corrected at the time of surgery (see below and refractive surgery part of the cataract section). The implant however only focuses at one distance (monofocal implant). The end result is that that whilst the distance vision is reasonable without glasses, for close work and reading in all situations, glasses are still required. For the vast majority of people this was the situation they were in prior to the onset of cataract, as they became reliant on glasses for reading  (presbyopic) with age (see normal ageing of the eye).

Nowadays there is the option of not only improving the vision with cataract surgery as above but, at the same time, reducing or even eradicating the need for reading glasses. This is achieved by using an implant that can focus both at near and distance. In fact the actual surgery is the same; all that differs is the type of implant that is used

Yet another option is for those people with astigmatism, (another type of refractive error requiring glasses). Standard cataract surgery does not correct this and therefore these people still need glasses both for distance and near vision. There are special implants (Toric implants) that correct the astigmatism so reducing the need for distance glasses in people with astigmatism (see below).

Eradicating, or much reducing, a person’s reliance on glasses after cataract surgery is often called premium cataract surgery.

Multifocal implants

The use of these types of implants is popular in the USA and many parts of Europe. It is less common in the UK mainly because they are not available on the NHS. In Europe almost all implants used for reducing the need for reading glasses are the multifocal type.

In reality we use not only near and distance vision, but intermediate as well. Some people are more reliant on their intermediate vision. Musicians are the classic example, reading sheet music further away than most people would read a book. Nowadays computer users form the largest group using intermediate vision. Some implants are better for intermediate vision than others. Also, some implants tend to work better than others in lower lighting conditions such as reading in bed.

 There are many different types of these implants, produced by different manufacturers. Most are designed for near and distant vision though some aim to correct for intermediate vision as well. They all have slightly different properties, although each manufacturer will always say their implant is the best! Most surgeons will have their favourites, usually the ones they have the most experience with.

The technology behind these implants, whilst impressive, is not perfect. There are advantages and disadvantages to both which need to be considered carefully before having this type of surgery.
Multifocal implants produce haloes and glare like phenomena, especially in night driving conditions. The vision is never quite as perfect as with a monofocal implant. Colour vision and depth perception can be slightly affected as well. That said, most people do adapt to these changes and eventually don’t notice them. They find the advantages far outweigh the disadvantages.

Accommodating implants have fewer side effects but tend to be not quite as effective for close work. They are also technically more difficult to put in the eye and less forgiving if there is a problem during surgery. At the time of writing most surgeons are using multifocal implants

Implants used to correct presbyopia

Implants used to correct presbyopia

Who should consider multifocal implants?

There are many factors to take into account and these should be discussed with your eye surgeon. The visual requirements for your work and hobbies are important. People who drive for a living or predominantly at night should be cautious. Consider any changing requirements, you may be about to retire for example. Think about what lighting levels you tend to do close work in, most multifocal implants work best for near vision in bright light. Try and decide if you need the best vision in the far, near or intermediate distance
It may be that to maximise one visual function you have to compromise on others. Golfers tend to prefer good distance vision whilst walkers often need better near vision to read maps. If your main need is an implant that functions best in bright light, expect to use reading glasses when reading in bed. Similarly smartphone, tablet, laptop or desktop computer users will have different requirements. Artists and photographers may not want to compromise their colour vision in any way.

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Glare can be a problem with multifocal implants

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In general those with a “type A” personality (engineers being a classic example), find the side effects of multifocal implants less easy to adapt to.

People with significant astigmatism (see below) will have problems with multifocals if the astigmatism is not corrected. There are now implants that are both multifocal and correct for astigmatism as well (toric multifocal).

Slightly short sighted people are used to excellent near vision without glasses and are more likely to be disappointed with the vision offered by multifocal implants. Longsighted people, especially those who require reading glasses as well are usually very happy with multifocal implants.

These implants will much reduce the need for glasses, but it has to be accepted that occasionally glasses will be required such as for reading small print in low light.

Toric implants – Correcting for astigmatism –

People with a significant degree of astigmatism (see refractive errors in the children’s section) will have worn glasses or contact lenses to correct for this most of their lives. Basically the optical power of the eye is greater in one plane.  These people will still have the astigmatism after cataract surgery. This means that they will continue to need glasses both for near and distance vision afterwards. Whilst many people are quite happy with this, it is now possible to put in an implant that corrects for the astigmatism as well as any co-existing long or short sight. This is called a Toric implant.  In most cases this will reduce the need for distance glasses in people previously completely dependant on them.

Anyone with a degree of astigmatism considering multifocal implants (in order to reduce the need for reading glasses), will require the astigmatism to be corrected as well for the multifocal implant to work properly. Therefore they will require a combination of multifocal and toric implant – a toric multifocal implant.

Premium Cataract Surgery from Derby Eye Surgery

Finally, if you do decide to have premium cataract surgery, it is not available on the NHS and you will have to fund it yourself.

General eye problems

Adult Squint
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AMD
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Presbyopia and normal ageing of the eye
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Cataract
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Cataract FAQ's
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Refractive surgery of the lens and correction of presbyopia
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Dry eye
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Glaucoma
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Retinal Vein Occlusion

 

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