What is premium IOL?
During a cataract operation the lens which has become cloudy is removed using small incision phacoemulsification technique and an intraocular lens (IOL) is inserted. Prior to the operation several eye measurements are taken to determine the power of this IOL. There are two types of Intraocular lenses (IOL).
Standard IOL: Also called monofocal IOL. The monofocal IOL gives clear focus at a fixed distance. So if the clear focus is for far distance you will need glasses to read books or work on the computer. If the clear focus is for near vision, you will need to wear glasses for distance vision such as while driving or watching television. It means with the monofocal IOL the spectacle dependence is certain.
Premium IOL: Premium IOLs are specially designed to provide an additional function. This can be to provide focus at all distances (multifocal IOL), to correct astigmatism (toric IOL) or do both (multifocal toric).
What is Multifocal IOL
Multifocal IOLs, as the name suggests, has multiple focal points. Different technologies exist in manufacturing these lenses. So the outcome of insertion of these lenses will be dependent on which type of lens is inserted. For example the ‘Bifocal’ lenses are designed to give two distinct areas of clear vision, near (eg read normal print books) and far (eg driving). The new ‘Trifocal’ technology gives an additional area of clear vision for intermediate distance (eg computer screen). The technology which uses Extended Depth of Focus (EDOF) allows smooth transition of vision from distance to near but less clear vision for near than the ‘Bifocal’ or ‘Trifocal’ technology. So EDOF lenses sit somewhere between monofocal and multifocal IOL. Because all multifocal IOLs split light into two or three focal points there is loss of contrast sensitivity by up to 20%. So the distance vision is not as crisp and clear as the monofocal IOL. These lenses are not funded on the NHS.
What is Toric IOL
The toric IOLs are designed to correct astigmatism. Some people’s cornea is shaped more like the side of a rugby ball than a football. This is known as astigmatism which is routinely corrected in your spectacle when you get glasses from optician. After the cataract surgery, you will continue to need to wear glasses all the time to correct this. However this astigmatism can be corrected by putting a toric IOL in the eye. A small amount of astigmatism does not need toric IOL. But if you have moderate to severe astigmatism, a toric IOL will remove the need to wear glasses for distant vision.
What is Multifocal Toric IOL
Multifocal Toric IOL combines features of both. If you have significant astigmatism, you can still have the multifocal IOL. But astigmatism will need to be corrected for the multifocal IOL to be effective. You will need multifocal toric IOL to achieve the desired outcome.
What is Monovision?
Monovision simply means vision with one eye only. If you want to see distance and near without needing to wear glasses but do not want multifocal IOL, it is possible to use standard lens with one eye focusing for near (to read a book) and other eye focusing for distance (drive a car). It is an inexpensive way to achieve near and distance vision without any potential side effects of multifocal IOLs. However only one eye is used at a time and as a result people do not have binocular vision either for distance or near vision.
Which IOL is suitable for me?
Not everyone is suitable for premium IOLs and not all IOLs will suit everyone. Some people may have certain eye conditions which would make it unsafe for them to have multifocal IOL. Besides, the selection of IOL is dependent on many other factors such as individual’s lifestyle, hobbies, professions etc. You need a full assessment with Mr Patwardhan to discuss whether you are a suitable candidate and which IOL is suitable for you.