What is a multi focal intraocular lens?
A multi focal intraocular lens is a lens implant used during cataract surgery with the aim of giving good distance vision, intermediate vision and near or reading vision. They do this by having more than one focal point. They are for people who desire spectacle independence. glasses may still be required for certain visual functions.
How does multifocal intraocular lens work?
Multifocal intraocular lenses work to improve your distance, intermediate and near vision. The surface of the lens has concentric rings. These allow the image you see to be focused at a number of different distances reducing the need for glasses.
Which is the best multifocal intraocular lens?
The best multifocal lens is one that provides focused vision at the distances that you require. Each brand has advantage and disadvantages.
Acrysoft reStor relies on the pupil size to give better visual outcomes at different distances. It has a central diffractive zone and an outer refractive zone. When the pupil is small the diffractive zone which provides clearer intermediate and near vision is used. When the pupil is larger the refractive zone for clearer distance vision is used. There is an option that aims to give reduced side effects for night driving. The distance vision may be slightly blurred,
reZoom has a number of different optical zones which form rings on the surface of the lens. This are to provide focused vision for distance, intermediate and near. This lens may require the need of glasses for reading in low light conditions.
Technis multifocal lenses are diffractive lenses with a wavefront technology to reduce spherical aberrations. This may help reduce the incidence of halos and glare at night. It has concentric rings on the lens to give focused vision and may be better at reading in low light conditions. The vision may be slightly blurred for distance and some may report the vision as waxy in particular light conditions.
With all multifocal lenses there is a process of adaptation and there is always a possibility that adaptation may not occur.
Which lens is better monofocal or multifocal?
Whether a multifocal or a monofocal lens is better depends on what you require. The evidence suggests that multifocal IOLs do offer better uncorrected near vision and less dependance on glasses compared to monofocal IOLs. This does however come with more visual phenomena such as halos and glare compared to monofocal intraocular lenses.
Are multifocal lenses worth it?
Multifocal lenses are worth considering if you are wanting to be spectacle independence in most situations and are happy to have the risk of more halos and glare as a result. They are shown to reduce the need for glasses in uptown 90% of visual functions. Glasses may still be required for some activities. If you are comfortable wearing glasses and are not wanting to have the increased risk of halos and glare a monofocal lens is probably more suitable for you.
How long does it take to get used to multifocal lens implants?
Getting used to multifocal lens implants can take time and varies from person to person. It may take a few days in some people particularly if they have been comfortable with multifocal contact lenses in the past. Others may take a 2-3 months or even 6 months. There are some people who may not get used to them at all. In these cases lens replacement surgery may be needed. Monofocal lenses would then be used in the second procedure.
What is the difference between toric and multifocal lenses?
A toric lens is a monofocal lens that tries to improve the visual acuity by correcting the astigmatism. Astigmatism occurs when there is an uneven surface to the cornea or the lens in the eye. A multifocal lenses trie to give glasses free vision at different distances to give more spectacle indepedendance. These lenses are used after cataract extraction and are inserted into the eye to give better vision.
What type of intraocular lens is most popular?
A monofocal lens remains the most common lens used worldwide. It is designed to give clear vision at a particular distance and provides the greatest contrast sensitivity. Greater contrast is useful for patients who have other conditions such as age-related macular degeneration or macular oedema. Monofocals are used when you have irregular corneal astigmatism or are happy wearing glasses. The clarity of the vision is less dependant on the pupil diameter. Night vision tends too have less glare and halos than the multifocal group. Glasses may be required for clear intermediate visual acuity and to correct any residual refractive error following the surgery.
Why are multifocal lenses so expensive?
Multifocal lenses are more expensive due to the additional technology used in designing the lenses. They are classes as a premium IOL although this does not mean that they are superior. They serve a different purpose to give better vision at an intermediate distance and reading. Cataract patients may want to consider these lenses if they want a range of visual function without glasses or corrective lenses. Photic phenomena such as glare and halos are a risk and some people are not able to adapt to these lenses. They are used in refractive lens exchange surgery is where that natural lens in the eye is removed and a multifocal is used to try and give vision that is less dependant on glasses. This is a form of refractive surgery.
Monofocals and multifocal IOL's can both lead to posterior capsule opacification. This is where the clear capsule that the new lens is placed in becomes cloudy with time following the IOL implantation. It requires a laser procedure done in the clinic to restore the clear vision.
How much do multifocal lenses cost?
Depending on the type of multifocal lens used they can cost from 300 to 600 pounds more than a standard monofocal lens. This is a significant difference in cost to some patients whilst others are happy to have this additional cost and potentially reduce their costs on having more expensive varifocal glasses in the future.
Can multifocal IOL correct astigmatism?
Multifocal lenses can correct regular astigmatism f they have a toric function included. They are then able to correct the astigmatism and provide less spectacle dependance for a range of vision compared to a monofocal lens.