An intraocular lens (IOL) is a tiny, artificial lens for the eye. It replaces the eye's natural lens that is removed during cataract surgery.
The lens bends (refracts) light rays that enter the eye, helping you to see. Your natural lens should be clear. But if you have a cataract, your lens has become cloudy. Things look blurry, hazy or less colourful with a cataract. Cataract surgery removes this cloudy lens and replaces it with a clear IOL to improve your vision.
IOLs come in different focusing powers, just like prescription eyeglasses or contact lenses. Your ophthalmologist will measure the length of your eye and the curve of your cornea. These measurements are used to set your IOLs focusing power.
Most IOLs are made of acrylic or other plastic compositions. They are also coated with a special material to help protect your eyes from the sun's harmful ultraviolet (UV) rays.
The most common type of lens used with cataract surgery is called a monofocal IOL. It has one focusing distance. It is set to focus for up close, medium range or distance vision. Most people have them set for clear distance vision. Then they wear eyeglasses for reading or close work
Some IOLs have different focusing powers within the same lens. These are called multifocal lenses. These IOLs reduce your dependence on glasses by giving you clear vision for more than one set distance. These IOLs provide both distance and near focus at the same time. The lens has different zones set at different powers.
For people with astigmatism, there is an IOL called a toric lens. Astigmatism is a refractive error caused by an uneven curve in your cornea or lens. The toric lens is designed to correct that refractive error.