Types of Intraocular Lenses (IOL's)
Up to this point, most lenses are replaced with monofocal intraocular lenses. These lenses only provide clear vision at one distance, far or near. A majority of patients prefer to see well far and afterward correct their near vision with the use of glasses or contact lenses.
With the advent of continued research, a second type of lens, the multifocal intraocular lens, was approved by the FDA in 1997 for use in cataracts surgery. This lens provides the patient with the ability to see both far and near, although far vision is still the clearer of the two. Unfortunately, not all patients are eligible for this type of IOL. The doctor will assess the candidate before choosing the multifocal IOL as a replacement. Additionally, some patients that are eligible and choose this form of lens may still require some minor vision correction aid for certain activities that entail near and extremely crisp, clear vision. Fewer individuals however, need glasses and contact lenses when fitted with a multifocal IOL than if a monofocal IOL had been used. Overall, patients who choose the multifocal over the monofocal intraocular lens have expressed greater satisfaction with the increased quality of living that their cataracts surgery has provided them. 15
Since multifocal IOL's have such great prospects for overall vision, researchers continue looking for a way to produce an IOL that will be ideal for a majority of patients and will correct both distant and near vision with equal success. A current possibility that meets these standards is the accommodating IOL.
In 2004, a new type of IOL, referred to as an accommodating IOL, was approved by the FDA for use in cataracts surgery. Candidates for this type of IOL are most often originally farsighted. The goal of this new IOL is to give patients the ability to see both near and far after cataracts surgery without corrective vision aids such as glasses or contact lenses. This lens is not entirely fixed in one position; it is somewhat moveable and changes its position in the eye ever so slightly as the eye attempts to focus on near or far objects. This differs from the monofocal and multifocal IOL's in that they are fixed in the eye and cannot change their focus.
And, finally, for those patients who underwent surgery in the past for cataracts but were not fitted with an IOL at the time, there is now secondary surgery will allows for fitting of an IOL after a previous surgery.
Depending on where in the eye the IOL is placed, there are several different names. An anterior chamber IOL is placed in front of the iris. Behind the iris there is a capsular bag, if the IOL is placed here it is known as a posterior chamber IOL. In the past, the anterior chamber IOL was the preferred method, however, over time and with increased techniques, the posterior chamber IOL is now the most commonly used. 14