Traditional monofocal lenses, including lens implants, focus light to only one point
in space. An accommodative lens is able to provide vision at multiple distances,
in a mechanism similar to the natural, crystalline lens.
An accommodative lens implant moves inside the eye as the eye's focusing muscle
contracts, mimicking the eye's natural ability to focus. This feature addresses
distance, intermediate and near vision and makes the recipient less dependent on
glasses or contact lenses. The lens is typically used in patients who have both
a cataract (cloudiness in the natural lens) and presbyopia (the loss of focusing
power of the natural lens that occurs in eyes older than 40 years).
The advantage of the accommodative IOL is that it has the potential to restore the
most natural focusing mechanism back to the aging eye of any IOL currently available.
The reason for this is that it is the only IOL that moves and, thus, changes the
focal length of the eye optics, similar to that of the natural lens. However, because
the lens is able to move inside the eye, some disadvantages occur.
The main disadvantage is that the lens must heal into place inside the natural lens
capsule of the eye from which the natural lens has been removed. The precise position
the accommodative IOL ends up in cannot be accurately predicted preoperatively and
depends on each individual eye's healing mechanism. The front to back position that
the lens ends up in determines both how clear the unaided distance vision will be
and also how much near vision will be available. On average, the accommodative IOL
heals into position such that the distance vision is quite good and "social" near
vision is achieved. If the lens heals into position slightly more forward than average,
the near vision may be better than "social" while the distance vision will be more
blurry. Conversely, if the lens heals into position slightly further back than average,
the distance vision will likely be quite good but the near vision will be more blurry.