Based on the focusing abilities they are classified into:

• Unifocal IOLs: these are the most commonly used lenses after cataract surgery; they can be for near, medium, or far vision. Most commonly patients choose the medium vision and use prescription glasses for reading ad distant vision.
• Multifocal IOLs: are lenses that have different zones for different ranges of vision. As cataract has a higher incidence in the elderly population such multifocal IOLs make a huge difference as they correct any underlying presbyopia present before the surgery. They help in near vision and distant vision though they might have a slightly burry image compared to accommodative IOLs in distant vision.
• Accommodative IOLs: are high-grade IOLs that provide clear vision over a range of visual fields. This is possible as the lens is rigid but the ‘legs’ used to attach the lens to the eye called haptics are flexible. This allows movement of the lens in the front to back axis and helps focus the image. They might produce a slightly blurred image while reading books but are superior compared to multifocal IOLs. Patients are comfortable using spectacles for reading when they have accommodative IOLs.
• Toric IOLs: are prescribed to correct astigmatism. This is a condition of impaired focusing of a visual image due to defects in the curvature of the eye.
• Aniridia IOLs: are used to correct defects in the iris (the colored portion of the eye around your pupil) caused either due to trauma or as a birth defect. These lenses have a black diaphragm which helps in cosmetic correction of the iris.

After performing scans and taking appropriate measurements your doctor will decide the power of the lens required to focus the image. After consulting you a decision will be taken as to the type of IOL that will be placed in your eye after the cataract surgery. Most IOLs are placed without any complications but slipping off the lens from its position can occur on rare occasions.