Your lens, which helps you focus, is removed during cataract surgery and is replaced with an artificial lens, the intra-ocular lens implant. This is made usually of acrylic and will, if surgery is uncomplicated, last a lifetime.
Traditionally, the (standard single-vision) lens was selected to allow clear focus for distance vision, but not for any other focal points, often needing ongoing use of glasses.
While glasses are still often required after cataract surgery, there are some advances in technology that means that it is possible to be glasses free or at least less reliant on glasses after cataract surgery.
New technology comes mainly in the form of a range of new lenses, and it is only after detailed discussion of these that it is possible to determine which best suit you and your lifestyle.
Multifocal lenses
Multifocal lenses are lenses that aim to correct vision for both near, mid-distance and distance. They work by using a diffraction grating with rings or zones at three different focal points in the lens. Unlike the natural lens, this lens does not change in thickness, it splits the light three ways to allow the three focal points. These require some time to get used to as the focal points are set and between these points, the vision is blurred. Multifocal lenses do not work for all patients and may cause some visual quality problems such as haloes and glare for example when driving at night.
An example of where this lens has proven useful is for a patient who was still working as a plumber and attended clinic for cataract surgery with three pairs of glasses for near, mid and distance vision. He reported that he would usually lose one of the pairs of glasses and this was affecting his ability to work. He got on very well with the multifocal lenses and now does not need any glasses at any distance after having bilateral uncomplicated cataract surgery.
Extended Depth of Field (EDOF) Lenses
These are the most modern version of the intra-ocular lenses. They offer an increased depth of field allowing good distance and some intermediate vision but no near vision. They do not cause significant glare or haloes like the multifocal lenses, whilst offering a greater depth of field than standard mono-focal lenses. This can be useful for example when wanting to be able to see for distance when driving, but also wanting to be able to clearly see the dashboard without needing glasses. As these do not offer reading vision, a pair of reading glasses will often be required. This is perhaps the most frequently used ‘premium lens’ for its advantages of an increased depth of field but with almost no disadvantage over the standard single vision lens.
Patients report that they can see clearly for distance as well as having a depth of field coming to within arms-length, often allowing screen use without glasses depending on font and screen size.
Monovision
This is a method of combining a clearer distance vision lens in one eye with a clearer focus at arms’ length (mid distance vision lens) in the other, is a good option if you are keen to be less glasses-dependent, but it only works if both eyes are healthy, aside from the cataract. A more gradual transition from the far vision in one eye and the mid-distance vision in the other can now be achieved by combining EDOF lenses.
Spreading the focus between the eyes in this way does not normally stop them working together or make you feel unbalanced, and it helps you to do more activities comfortably without glasses. As the brain does the work of choosing the better image so that the better focused eye is selected, there is a small chance that this arrangement may not be tolerated. Certain tasks will still require ‘top-up’ glasses for at least some activities after surgery and it may take you a few weeks to get used to your new vision. This option requires careful consideration and may not be suitable for all patients.
Having some knowledge of the options and being more informed helps your consultant make the right decision for you as the old saying goes that when there are a number of options in medicine, it means there is no ‘best’ option for all and the treatment must be tailored to fit the individual.