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Crystalens

When cataracts develop, there are now more options than ever for synthetic, replacement lenses, called intraocular lenses (IOLs). These possibilities include both monofocal and multifocal IOLs, the latter of which have two or more zones of thickness and curvature that the brain learns how to look through selectively. While giving high quality results, these multifocal IOLs still fail to do something that occurs naturally in the human eye: To change the shape of the lens adaptively in order to switch from near distance to far distance, or vice versa.

The development of accommodative IOLs relies on the same eye muscles, called ciliary muscles, that allow for normal accommodation. The ciliary muscles attach to the lens, and when they contract in young and healthy eyes, they pull on the lens to make it less thick and slightly less curved, allowing focused vision at close range. When the ciliaries relax, the pupil goes back to its normal, more curved, thicker shape, focusing further away. With age, the lens becomes stiffer and doesn’t change shape as much as it should when the ciliary muscles contract. This leads to age-related far-sightedness, called presbyopia, with increasing difficulty focusing on nearby small print or objects. However, the ciliary muscles themselves still work, even if a bit weakened with age, and remain able to contract and relax. It is the stiffening lens that fails to respond adequately.

Accommodative IOLs came on the scene in the past decade with FDA approval of the Crystalens in 2003. These prosthetic visual devices consist of the central lens part of the IOL, called the optic, plus four little handles, to which the ciliary muscles of the eye are attached. Whereas the normal lens will stretch and become thinner (less curved) in response to the ciliary muscles contracting, the Crystalens will move slightly forward and back with ciliary contraction and relaxation. Hence the same net result is achieved – accommodation to focus at short distances – with a slightly different approach than nature uses. Accommodative IOLs that actually change shape in response to ciliary muscles are also under development and testing.

Of course, the main reason for lens replacement – the exchange of a cloudy, cataract-filled lens for a new, clear one – is also accomplished. This is always the case, even if a small percentage of people do not achieve complete resolution of their presbyopia and sometimes still need reading glasses. The majority of patients receiving an accommodative Crystalens are thrilled to have both their cataracts and their presbyopia corrected simultaneously. Nonetheless, insurance companies continue to view vision gains beyond improved clarity as a luxury, given that using corrective eyeglasses or contacts lenses for presbyopia is easily done.

Therefore, insurance coverage for the accommodative Crystalens, and all other forms of ‘premium’ IOLs, will only be for what the cost of a basic monofocal lens would be. The difference is in the neighborhood of two thousand dollars, and the patient must absorb this as an “out-of-pocket” expense – though one can ask the eye surgeon for a partial reduction of their fee. One must remember, though, that it is not just the premium lens itself that is more expensive, but that these generally involve a bit more time and manipulation to implant than the basic monofocal variety. In other words, you get what you pay for. For those who can afford the difference, the accommodative Crystalens gives a result as close to natural vision as is currently possible.

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