In cataract surgery, the cloudy natural lens is replaced by a clear artificial lens implant, also known as an "IOL". IOL stands for Intra-Ocular Lens. There are many types of lens implants, each with their own pros & cons. They come in different sizes, strengths, and features. If you are considering cataract surgery, you should familiarize yourself with the different options. I hope this information helps!
The most basic lens implant is called a "Monofocal" lens implant. Mono = single, and as you might have predicted, a mono-focal lens implant can focus things you see from only one distance. As long as you don't have a significant amount of astigmatism, this lens implant can focus objects that are at a single distance away from you. Most people choose to have their eye focused at a distance far away. That way you can see well while driving or watching TV. Glasses will be needed to see clearly for other distances (such as reading or using a computer). If one has astigmatism, glasses will be needed to be worn all the time to see clearly, as the glasses neutralize the astigmatism.
If one has astigmatism, they should consider a Toric lens. This type of lens is designed to neutralize astigmatism. With astigmatism, the front of the eye is not perfectly spherical, and so the eye does not focus light in a symmetric way. Vertical and horizontal beams of light are focused differently and asymmetrically. So a Toric lens tries to neutralize this asymmetry. This kind of lens implant is designed to neutralize your eyes asymmetry, giving you clearer and less distorted vision. Toric IOL's are the "Yin" to your "Yang".
A Multifocal lens implant can focus things you see at multiple distances. Hence it's called "Multi-focal". If you want the best chance of not needing glasses anymore to see clearly at multiple distances, discuss this option with your doctor. They work well in cataract patients with an otherwise healthy eye. Current multi-focals offer three "sweet spots" of vision, which are far away, intermediate distance (think of a computer), and near (like when reading a book). If a patient has astigmatism, it will also need to be neutralized to see clearly, which is why Multi-focal lens implants are available as a combination: Multi-Focal-Toric. Since these IOL's split the light energy that enters your eye, sharpest vision is achieved when the lighting in your environment is good. The more light energy, the better. Some patients may notice halos and/or starbursts around lights at night. These are tolerated well by the majority of patients.
Extended Depth of Focus (EDOF) lenses attempt to give patients a continuous range of vision, rather than multiple focus points. Current generation EDOF lenses focus your vision from far away objects, and down to intermediate distance vision, such as using a computer. These lens implants generally give great quality distance and intermediate vision, but many patients still need some low power reading glasses for up-close vision. Because these lens implants attempt to give you clear vision from far all the way down to intermediate vision, some patients may notice starbursts from sources of light when in the dark.
Accommodative Lenses attempt to recreate the eyes natural ability to adjust its focal length depending on the activity one is performing. If you are looking far away, far distance should be in focus. If you are looking at something up close, the near should be in focus (like portrait mode). A lens that can provide this would be ideal. While this sounds amazing in theory, technology hasn't advanced far enough where IOL's can provide this experience consistently and reliably. But I'm optimistic that one day we will get there.
