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A lens implant is a mechanical device that is surgically implanted to replace the natural lens of the eye. Most often, this procedure is performed to improve impaired vision due to cataracts. However, it may also be done to correct certain refractive disorders, such as myopia or astigmatism. Remarkably, the patient is usually awake for the procedure, being prepped with only a local anesthesia. Equally remarkable is that most lens implants can be in place in under an hour, with a recovery period of only one to three weeks.
There are different types of lenses used in lens replacement surgery. First, a lens implant is generally referred to as an intraocular lens, or IOL. Initially, all IOLs were monofocal, meaning that they were intended to correct vision in only one direction -- either near or far. This is somewhat limiting since it means wearing glasses when eyesight of a different distance is needed. This kind of lens implant may be particularly disappointing for patients affected by presbyopia, or age-related farsightedness.
While monofocal IOLs are still appropriate for some patients, there have been new developments over the years to help others. For example, the multifocal lens implant enables the recipient to see clearly at all distances, without the assistance of eyeglasses or contact lenses. In this class, there are several products designed to address more specific needs. In fact, there are even lens implants that help to reduce glare and minimize sensitivity to light.
There is another key difference between monofocal and multifocal IOLs to consider. Unlike the former, which are “fixed,” some multifocal IOLs are designed to function just like a natural lens, which adjusts in order to change focus. This physical characteristic, technically known as “accommodation,” may require a longer period of adjustment for the patient. In fact, retraining the brain to target and interpret images at varying distances with this type of lens implant can be difficult unless both eyes receive one at the same time.
Unfortunately, not everyone with poor vision is a candidate for lens implant surgery. First, eye growth must be complete, which generally excludes anyone under the age of 40 years. In addition, the patient should be in overall good health, possess sufficient thickness of the cornea, and experience balanced refraction for a minimum of six months prior to surgery. Finally, certain medical conditions usually cause rejection for this procedure, such as pregnancy, HIV infection, hepatitis C, diabetes, and the presence of a pacemaker.
While adverse reactions are relatively rare, there are certain risks involved with getting a lens implant. Corneal edema, or swelling, is the most common complication, but this usually clears up on its own within a few days after surgery. Infection is the most serious concern since it can lead to blindness, if left untreated. Additional risk factors include glaucoma, retinal detachment and, ironically, cataract development. However, it is estimated that only five percent of lens implant recipients experience any of these complications.