by Patricia Woloch
As we age, changes take place in the eyes as well as many other parts of the body. Two of the ways our vision gradually becomes impaired are cataracts and presbyopia.
* Cataracts are opacities in the eye's lens - the lens transparency becomes impaired by clumping of the proteins within the lens. The clumps prevent light from reaching the retina ("camera film" at the back of the eye). The retina is full of light-sensitive cells which receive images and send them to the brain via the optic nerve. When some of the light is blocked before it reaches the retina, that image information is incomplete, and we have blurry vision.
* Presbyopia is blurry near vision which sends us out to the store for reading glasses at around the age of 40. Our eyes may still be 20/20, but aging reduces the lens' ability to change curvature. It cannot become convex enough to bend light rays coming in from close-by objects. It remains too flat, so that the light focuses behind the retina, giving you blurry near vision. Vision for distant objects remains clear, since light from far away doesn't need to be bent as much as light coming from close-up.
So far, eye surgeons have not found a way to remove cataracts from the lens, nor a way to restore the lens' lost ability to become steeply curved (convex). Therefore, treatment for both cataracts and presbyopia is typically done by inserting an intraocular lens (IOL) to replace the natural lens.
Loss of the Natural Lens Means Loss of Accommodation
If you stop reading this text and examine your hands for a minute, then look out the window at a tree or the building across the road, you are using your eyes' ability to accommodate. The eye's lens changes its curvature each time we change our visual focus. It is controlled by tiny muscles at each side (ciliary muscles), which contract or relax. This causes the lens to become flatter or more curved according to whether we're looking at something close up or far away. This is how we manage to see clearly at all distances with no conscious effort. But if the natural lens is removed, so is this ability to accommodate.
What is an IOL?
It is a microscopically precise artificial lens which in one of two ways can mimic the accommodative ability of the natural lens.
1. The IOLs called ReZoom™ and ReSTOR® have concentric areas built into their structure, each of which is set for clear vision at specific distances. The brain learns to use vision information in this slightly different way, so that we continue to have clear vision at all distances.
2. The IOL called Crystalens™ has the same effect but without any built-in areas. Instead, it is attached to the same muscles which had control of the natural lens. This gives you the same automatic adjustment for distance, with the Crystalens moving forward for far vision and back for near vision.
The IOL Procedure
It is an outpatient procedure and takes less than an hour. Using ultrasound, your eye surgeon would carefully break up the natural lens and remove the small pieces, both done through a very small incision outside your visual field. Then through that same little incision, he would insert a folded IOL. It will unfold automatically and place itself into position. The incision will heal without any stitches. Recovery is brief, so that you can usually go back to work or normal activity after a day or two.
The first step in learning whether or not an IOL would be the best way to improve your vision would be to schedule a consultation with a fully-qualified and experienced eye surgeon. You could ask your questions and get a clear understanding of which option would be best for you, and why. In this era of sophisticated eye surgery, there is usually no need to live with faulty vision, losing contact lenses or reading glasses, and having to get them constantly updated. Why not start now on the quick and easy road to improved vision?
About the Author
If you're interested in learning more about IOLs, contact the Northeastern Eye Institute for more information or to schedule a consultation.
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