Accommodating IOLs – Correction for Cataracts & Reading Vision
Accommodating IOLs are an advanced type of intraocular lens implant designed to correct presbyopia as well as nearsightedness and farsightedness.
Currently available accommodating IOLs do not correct astigmatism, but several options exist for the correction of astigmatism after accommodative IOL surgery, including standard LASIK, custom LASIK (also called wavefront LASIK), PRK, and other laser vision correction procedures. Another option is a non-laser procedure called limbal relaxing incisions.
Accommodating IOLs can be used in refractive cataract surgery for cataract patients or they can be used in refractive lens exchange (RLE) for people who don't have cataracts, but want lens-based vision correction surgery to reduce the need for reading glasses.
How Accommodating IOLs Work
Accommodating IOLs reduce the need for reading glasses by increasing the magnifying power of the eye in response to focusing effort (a process called accommodation). But these lenses work differently than the eye's natural lens.
The natural lens of the eye is flexible and capable of changing shape in young persons. The lens is held in place within the eye by fibrous strands, or zonules, which attach the outer capsule of the lens to the focusing muscle (called the ciliary muscle) that surrounds the lens. Contraction and relaxation of the ciliary muscle changes the tension in the zonules, which in turn changes the shape of the lens to provide the correct focusing power for seeing objects at all distances.
To see clearly far away, the focusing muscle relaxes and the lens becomes flatter. To see clearly up close, the ciliary muscle contracts and the lens becomes more curved.
Because the central optical portion of an accommodating IOLs typically is less flexible than the eye's natural lens, these intraocular lenses must work in a different way. Instead of changing shape, an accommodative IOL moves slightly forward within the eye in response to focusing effort.
This forward movement is made possible by the "legs" (or haptics) of the accommodating IOLs, which are flexible. When an accommodating IOL is implanted in the eye, the haptics of the IOL are positioned within the capsule of the eye's natural lens after the lens has been removed.
When the ciliary muscle contracts, this action loosens the zonules connecting the muscle to the lens capsule. It also increases pressure exerted by the vitreous body — the clear, gel-like material filling the back of the eyeball, behind the lens capsule. These two actions allow the accommodating IOL to move slightly forward, increasing the magnifying power of the eye and providing for better reading vision. When the focusing muscle relaxes (as the person looks across the room, for example), the accommodating IOL returns to its original position and provides for clear distance vision.
Some accommodating IOLs also have an optic (the central part of the IOL that focuses light) that can partially flex. As the IOL moves forward during focusing effort, the optic may also flex slightly, adding to the eye's magnifying power for reading.
Who is a Candidate for Accommodative IOLs?
Candidacy for accommodating IOL surgery is determined using the same criteria used to determine candidacy for either refractive cataract surgery or refractive lens exchange. Candidates also must understand and be willing to accept the potential risks and complications associated with accommodating IOL surgery.
It's also important for accommodating IOL candidates to have realistic expectations about the outcome of their surgery. Accommodating IOLs cannot restore a person's near vision to the same level it was prior to the development of presbyopia, and other age-related changes in the eye may continue to affect visual acuity after surgery.
You still may need reading glasses after accommodating IOL surgery to see small print and for other specific near vision tasks. A realistic expectation is that you will be less dependent on reading glasses after accommodating IOL surgery, and that you will be able to read and see many things up close better than you could prior to surgery without bifocals or reading glasses.
In some cases, an accommodating IOL may be properly implanted, but the ciliary muscle or the zonules attaching the lens capsule to the muscle may no longer function properly. In these cases, an accommodating IOL may not be able to improve near vision, but it will still function well as a monofocal (single power) IOL for good distance vision.
Cost of Accommodative IOLs
Accommodating IOLs are premium intraocular lenses and cost significantly more than conventional IOLs. If you choose to have an accommodating IOL implanted during cataract surgery, you typically will have to pay the difference between the cost of the accommodating IOL and the amount your insurance plan allows for the cost of a conventional IOL. Ask your cataract surgeon for details.
More Information About Accommodating IOLs
Currently, only one brand of accommodating IOL is FDA-approved for use in the United States — the Crystalens accommodating IOL produced by Bausch & Lomb (Rochester, NY). However, other brands are currently being clinically tested and may be available soon.
Note: This information is for general education purposes only. It is not to be used as a substitute for medical advice from your eye doctor or refractive surgeon.
