Refractive Lens Exchange
Refractive lens exchange, simply put, is cataract surgery for someone without visually significant cataracts. Refractive lens exchange can also correct extreme glasses prescriptions that fall outside the range of other surgical techniques such as LASIK.
Many people with presbyopia, usually in their fifties, choose to have lens-replacement surgery before cataracts have a chance to develop. These people don't want to wear eyeglasses or contacts, and they choose not to have other forms of refractive-error correction, such as LASIK, since within a few years they might well need cataract surgery. With refractive lens exchange, they are basically killing two birds with one stone - eliminating the need for glasses now and the need for cataract surgery later.
Replacement Lenses
More than 99 percent of cataract surgery patients have intraocular lenses (IOLs) implanted when the natural lenses are removed. Since the cloudy human lens is removed from the eye during cataract surgery, it must be replaced by a man-made lens, the IOL, in order for the eye to recover vision.
Modern IOLs are made of acrylic, silicone, or collagen polymers. They can be rolled or folded to fit through a very small incision. Once inside, they unfold to about a quarter of an inch in size. Side struts, called haptics, hold them in place within the capsule.
The lens implants become part of the eye. They are safe, stable, and reliable, and they require no care or maintenance other than general practices for good eye health.
Research and development are continually producing IOL refinements: Toric lenses to correct astigmatism, blue-blocking lenses to filter out ultraviolet and high-energy blue light, and aspheric lenses for better contrast sensitivity are just a few examples.
Intraocular lenses fall into two general categories: single focus (standard) and full focus (premium). Imagine your range of vision as encompassing five zones, from nearest to farthest. Single focus lenses provide good vision in only one or two zones, whereas full-focus lenses enable you to see well in three to five zones.
Single-Focus lOLs
A single-focus IOL, also called a monofocal IOL - like a disposable camera lens - a single fixed focal point, usually designed for mid-distance vision, so you'll need eyeglasses to see near objects and those farther than
arm's length. Still, your vision will be better at some distances than it was before surgery.
If you don't mind wearing glasses, monofocal lense might work well for you. If you choose the standard single-focus IOL, you should be prepared to wear glasses for many or most activities.
Full-Focus lOLs
Full-focus lOLs are more like high-end Nikon camera lenses, automatically adjusting their focus to provide good near, mid-range, and distance vision without glasses. Many patients who choose full-focus IOLs can do almost anything they wish without glasses. Manufacturers of full-focus lenses use different technologies in the production of lenses.
Full-Focus Multifocal IOLs
Multifocal IOLs have different focusing zones built into the lens, allowing a wide range of vision with decreased dependence on glasses. Since these IOLs work by dividing the light that enters the eye, they can produce glare and halos, particularly at night.
Full-Focus Accommodating Lenses
Most lOLs, once implanted, remain in a fixed position within the lens capsule. Accommodating lenses, also called adaptive lenses, respond to contracting and loosening of the ciliary muscles, moving within the eye for smooth accommodation through the entire range of vision. The ciliary muscle changes the shape of the synthetic lens, just as it did with the natural lens while it was still flexible, before the onset of presbyopia.
Though your vision will be better immediately after implantation of an adaptive lens, it can take up to a year for the ciliary muscle to get used to the new lens. During that time, you'll experience slight fluctuations in clarity of vision.
Monovision
Monovision refers to implanting lOLs in different strengths, making one eye distance-dominant and the other eye more near-dominant. If the implants are premium accommodating IOLs, a wide range of sharp vision without glasses is possible.
If you've successfully worn monofocal contact lenses, you might be a good candidate for monovision. The brain usually adapts to the difference in refraction. Very seldom are the results unsatisfactory, requiring corrective LASIK. If you and your doctor are considering monovision for your lens implants, he or she might want you to try wearing monofocal contact lenses for a while before your surgery.
Piggyback Lenses
If you have had cataract surgery and you're not satisfied with the results, it's possible to implant new lenses on top of the existing ones. This process is called piggybacking. It can't correct every type of damage, and the best option is to choose your surgeon carefully so that the procedure will be done right the first time. To find out more, you can check out How Do Lenses Correct Vision.