Multifocal lens implants (known as Intraocular Lenses or IOLs) for cataract surgery are an innovative technology designed to reduce your dependence on eyeglasses as compared to a standard "single focus" lens implant. A standard lens implant provides your eye with optimum focus, but at a set distance that does not change. You would then need to wear glasses in order to shift this focus closer or farther away.
With bifocal eyeglasses, you look through the top part of the lens for distance, and through the bottom area of the lens for near. The multifocal lens implant is a specially engineered optic, which provides both, a distance focus, and a near focus at all times. Your brain will learn to automatically select the focus that is appropriate for the task at hand.
For the majority of patients, multifocal lens implants will not entirely eliminate eyeglasses. There may be situations where the print or the images are simply to small or too far away to see without the help of glasses. Your retina must be completely healthy to achieve the optimum results.
Depending upon the size of your pupils, you may see linear halos at night, which appear as thin circles within a light source. These halos are different from, and much less problematic than those caused by cataracts. They relate to viewing distant lights through both the near and far focusing zones of the lens. These halos become less noticeable and distracting over time as the brain learns to selectively ignore them through a process called neuroadaptation. How quickly this adjustment occurs varies for different people, but usually over a one year period of time. Even a standard lens implant can produce some halos at night. This is because the pupil dilates in the dark allowing more light to enter the interior of the eyeball and scatter off of the peripheral parts of the lens implant. Many patients seem to hardly notice them at all.
Yes, this is possible when the other eye already has a standard implant, or when there is no cataract in the opposite eye. Although some doctors do this, Dr. Lindahl prefers to implant them bilaterally, as they perform best as a binocular system.
This is always possible but entails the risks of additional surgery. However, there may be a rare individual for whom the halos continue to be unacceptable, and who then elects to have the multifocal lens replaced with a standard lens implant. One should not rush into this decision because the ghost images nearly always improve over time.
Unfortunately it will not cover the cost. Health insurance, whether a PPO, HMO, or Medicare, cover a cataract operation with a standard lens implant when the cataract is bad enough to be considered "medically necessary." The additional fee to upgrade from the conventional to the multifocal lens implant is not covered, because the added convenience of reducing your dependence on glasses is not considered "medically necessary."
The multifocal lens implant is the one technology that can allow a 50+ year-old to have focus both far and near without glasses. For this reason, people over the age of 50 wearing strong prescription glasses may elect to have multifocal lens implants in order to see better without glasses. However, with no cataract present, health insurance covers none of the costs. The procedure is performed the same way as for cataract surgery. Therefore, patients electing to have lens implant surgery to reduce their need for glasses, will never have to worry about developing cataracts later in life.
Every artificial lens implant model, both standard and multifocal, is manufactured in more than 60 different powers. As with prescription eyeglasses or contact lenses, it is important to match the appropriate artificial lens implant power to your eye. The appropriate power of the lens implant can be estimated using mathematical formulas that utilize preoperative measurements of your eye's dimensions. For a multifocal lens implant to work well, it is very important for the selected lens power to match your individual eye. Every type of eye procedure intending to reduce a person's need for glasses may need to be "enhanced" with additional surgery. This unpredictability is understandable because we are working with human tissue, not machining plastic or metal. The need will also depend on how much better one wants to see without glasses.
The decision about which type of artificial lens implant to have will only affect your ability to see without glasses following cataract surgery. With both standard and multifocal lens implants, most people will see reasonably well in the distance without any glasses. Multifocal lens implants will provide the added convenience of being able to read many things without glasses. Multifocal implants are an excellent option for patients who already need cataract surgery and want to decrease their reliance on glasses, and should greatly improve the odds that you will be able to read and see better overall without glasses.