What is an accommodating IOL?

A key function of the human eye is to focus on objects at various distances. This ability relies on the lens of the eye changing shape. The muscles surrounding the lens contract and relax in order to change the shape of the lens, and therefore the focus of the vision. When an object is far away the muscles will relax, flattening the lens. If an object is very close then it will contract, curving the lens. The trouble is, as we age the lens becomes less flexible.

Conventional IOLs are designed primarily for distance vision. This means that people who wear them are unable to effectively switch their focus when the viewing distance changes. Though the standard IOL implant can be a very effective remedy for cataracts, their inability to switch focus leaves their users at a distinct disadvantage.

The flexibility of the eye's natural lens is very difficult to assimilate artificially. However, accommodating IOLs present a solution to this problem. By interacting with the ciliary muscles and zonules within the eye, accommodating IOLs are able to move forwards and backwards by attaching themselves to the mechanisms that adjust focus in a normal, functioning eye. Rather than the shape of the lens changing, accommodating IOLs move, very slightly, forward and backwards in response to changes in distance. This slight forwards and backwards motion is made possible by contraction and relaxation of the ciliary muscle, which loosens the zonules, and the pressure caused by the vitreous body of the eye. The lens uses the natural mechanisms that switch focus in a normal eye to make the accommodating IOL work.

These accommodating IOLs are made using a long hinged plate design with polyimide loops at the end of the haptics. It is these haptics (or 'legs') which provide the flexibility in the IOL. The hinges allow for unlimited flexing within the eye and are made using an advanced silicone to allow for this. The lens itself is a 4.5 mm square edged optic. Some accommodating IOLs also include a central, focusing optic which is partially flexible. This flexibility gives the lens a far greater ability to magnify when viewing objects which are very close, like when reading.

Accommodating IOLs offer many clear benefits.

They are able to adjust their focus giving excellent vision whether the object is far away, near, or somewhere in between. They also provide the user with vision free of unwanted retinal aberrations, whilst giving no decrease in central system adaptation or contrast sensitivity.

Also, in order to reduce halos, glares and other aberrations, the light is focused on a single, precise point. Following cataract surgery, accommodating IOLs are an effective way of reducing dependency on glasses.

For some, they also offer a viable alternative to monovision and refractive lens exchange (RLE).

Who are Accommodating IOLs designed for?

Accommodating IOLs rely on the ability of the ciliary muscles and zonules to move the haptics of the lens. If the patient no longer has this ability then the accommodating IOL will simply function as a standard, stationary IOL.

Good candidates for accommodating IOLs are people over 50 who are suffering from cataracts, myopia, hyperopia and presbyopia.

Before anyone embarks on having accommodating IOL surgery they need to be realistic about the potential outcomes. No matter how successful the surgery is, it will not be able to restore vision to the same standard it was prior to the onset of presbyopia. It is also worth considering that an eye implanted with an accommodating IOL is just as susceptible to changes that may occur due to a patient's age as an ordinary eye might be.

What results can you realistically expect with accommodating IOL surgery?

The surgery is designed to improve both your long and near distance vision. Realistically, you can expect to see an increase in your distance vision as well as a decreased dependence on reading glasses or bifocals for your near vision. It is very important however, that you do not expect to have your dependence on glasses removed completely.

Following the implantation of an accommodating IOL the prescribed care is very similar to standard IOLs. One very important addition is the strict regimen of ophthalmologic exercises that must be made part of the patients daily routine. These exercises will include close reading activities, such as word games and puzzles, and are designed to tone and strengthen the ciliary muscles. These exercises are critical in order for the patient to get the full benefit of an accommodating IOL. Usually these exercises are performed for three to six months following the surgery and the progress of the patient is closely monitored by an eye care professional.


A little about the lenses we use

The accommodating IOL that we use in our procedures is called a Crystalens AO. The Crystalens AO is designed specifically to treat both presbyopia and cataracts. It is a very dynamic lens that adjusts to give great increases in vision. The Crystalens AO, though it still operates by moving forwards and backwards to shift focus, is a very flexible IOL. This means that those using them will enjoy much better results when viewing objects that are close to them.

The Crystalens AO is the only accommodating lens to be approved by the FDA (Food and Drug Administration) in the US. It is a highly effective lens which has been proven to significantly reduce the experiencing of halo's and glares as well as greatly increasing night vision. Another key benefit of the Crystalens AO, is that rather than projecting many images to the back of the eye, as many multifocal lenses do, it only projects one. This makes it far easier for your brain to process, due to a decreased need to neuroadapt, resulting in a significant improvement in sight.

In clinical trials 88.4% of patients implanted with a Crystalens AO could see better at all distances. This is in comparison to just 35.9% of patients implanted with a standard IOL. Crystalens AO has also proven to have excellent longevity. The majority of patients implanted with the lens still report excellent vision 7 years after the operation. Worldwide, over 200,000 crystalens IOLs have been implanted. A number which rises on a daily basis.


More on Accommodative IOL's

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If you have been affected by any of the symptoms mentioned above, please don't hesitate to give us a call.

We have a team of experts on stand-by who are ready to take your call at our Manchester (0161 907 2685) Clinic or our Blackpool (01253 308 031) Clinic.