The Monofocal IOL
Monofocal IOLs have one single focus, this means that near object may not be completely focused without the possible need for reading spectacles. To enable a person to see over a greater range without the need for glasses or contact lenses there are several other types of intraocular lenses.
The Multifocal IOL
Multifocal IOLs work by having various fixed areas of focus within the one lens. This means that a person can choose to concentrate on either a distant object or a near object. The brain has to learn to select the visual information it needs to make an image for either near or distant objects. This means that multifocal IOLs do require some adjustment. A person may adjust better to multifocal IOLs if they are placed in both eyes. These types of intraocular contact lenses work in a similar way to multifocal glasses.
The Accommodating IOL
Accommodating IOLs work by using the natural focusing mechanism of the eye. There are various designs but they all tend to work on the principal that as a person tries to focus on a near object the ciliary muscle in the eye contracts and causes the accommodating IOL to either shift forwards or change shape allowing the eye to change its focus.