What are the different types of Intraocular Lenses (IOLs)?
When the natural human lens becomes cloudy, it is called a cataract. Intraocular lenses (IOLs) are artificial lenses that are placed inside the eye to take the place of the natural human lens. Usually this is performed immediately following removal of a cataract as part of cataract surgery. These lenses are most commonly made of acrylic and are not able to be felt. Be aware that intraocular lenses are very different from contact lenses because IOLs are inserted into the eye and are considered permanent. They can be removed or exchanged, but this is performed rarely and only in extreme circumstances. Intraocular lenses are similiar to cars in that there are many makes and models. Personal preference, performance, and cost factor into the best-individualized choice.
Below are some videos that will help you understand these lens and laser options.
Most IOLs are monofocal, meaning they provide the best focus at one distance. The focal distance of the lens is determined by the doctor and the patient and is usually set for near, intermediate, or distance vision. A majority of patients choose to have both eyes focused for distance and use reading glasses for near vision. Some patients choose monovision in which the dominant eye is targeted for near or intermediate, and the non-dominent eye is targeted for distance. This helps to minimize the need for reading glasses after cataract surgery.
Some IOLs are multi-focal, meaning they provide focus at more than one distance. These IOLs use special optics to allow for both distance and near vision, or distance and intermediate vision for each eye. The cons of these types of lenses is that the vision is usually not as sharp for the distance or near as it would be with a mono-focal IOL.
Additionally, they have extra associated costs and some patients do not like the percieved “soft focus” of their vision with these IOLs. It is very rare that I recommend multi-focal IOLs.
Some IOLs are toric, meaning they provide some correction for regular astigmatism. These IOLs can be useful to help reduce or eliminate the need for astigmatism correction in glasses or contacts. They are only able to correct certain types and certain degrees of astigmatism and therefore are not appropriate for all patients. Again, these types of lenses have extra associated costs. I usually only recommend toric IOLs for patients with moderate to high levels of regular astigmatism.
The primary goal of cataract surgery is not to eliminate the need for glasses or contacts. The aim is clearing the opacities in the visual axis so that light can be focused on the retina to improve functional vision. It is important to keep in mind that after any type of cataract surgery with any type of intraocular lens, glasses or contacts may be necessary in order to get the best possible vision.