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Multifocal Lens Implants

Vision Correction At All Distances
Bring Your World Into Focus

Another tremendous improvement in an already great technology, multifocal lens implants are providing people with an even greater level of visual freedom. Intraocular lens implants (IOLs) were first developed over 50 years ago and have been used routinely to correct vision after cataract surgery since the 1980’s. Traditional lens implants do an excellent job for many people in restoring vision after the removal of their natural lens. These implants provide good focusing at one specific distance (monofocal) usually resulting in excellent distance vision and pretty good intermediate vision. To be able to also have excellent reading or near vision, reading lasses are usually required.

Multifocal Lens Implants

For people with more demanding lifestyles, new multifocal lens implants provide much greater visual freedom. Multifocal lens implants offer a more complete range of good vision, from distance to near reading vision, without cumbersome or unsightly reading glasses or bifocals.

Normal Vision

Vision occurs when light passes through the cornea and the lens of the eye and is focused onto the retina. The retina then transmits the image to the brain via the optic nerve. When light passes through a curved surface the rays are bent (refracted). The steeper the curved surface, the greater the bend or refraction of light and the shorter the focal length. The curve of the cornea provides most of the focusing for the eye. The curve of the lens of the eye fine tunes vision to adjust focus (accommodate) between distant and near objects.

At rest, the lens of the eye is in a flatter state and focuses on distant objects. The shape of the lens in controlled by relaxation or contraction of small fibers (zonules) and muscles (ciliary body) which hold the lens in place. When we change attention from a distant object to a near object, the lens almost instantly, gets rounder and the focal length is shortened until the near object of our attention comes into focus.

Presbyopia

At birth the natural lens is soft and flexible, and its shape is easily controlled. As we mature, it becomes less elastic and its ability to change shape is reduced. About the age of 40, the elasticity of the lens has diminished to the point where its ability to change shape can no longer accommodate focusing changes from distance to near. This lack of accommodation is called Presbyopia and results in blurred near vision and difficulty doing close work like reading. When presbyopia begins many people find reading difficult and hold reading material further away in an attempt to see more clearly. Initially, the reading glasses or bifocals are prescribed for presbyopia and eventually some people need trifocals. Multifocal IOL’s can be a great choice for people with presbyopia.

The lens implant procedure

Although similar to traditional cataract and lens implant surgery, multifocal lens implant surgery is more complex and precise. Sophisticated testing and preparation before surgery is required by the doctors and the patient. Pre-surgery examinations are conducted and questions asked to determine unique distant, intermediate and near vision needs. The patient and doctor together must determine the most appropriate implant solution.

What to expect

The lens implant procedure is typically performed on an outpatient basis. You will be asked to arrive about an hour before the procedure. The doctor will place drops in your eye to numb it and dilate your pupil. You may also be given medication to help you relax.

The entire procedure should take less than 30-45 minutes. As you lie on your back, the doctor will use a device to hold your eyelid open and you will be asked to look up into a light. There may be a feeling of slight pressure, but you shouldn’t feel any pain. The doctor will then make a small incision in your eye, remove the natural lens and replace it with a lens implant.

Following the procedure, drops will be put into your eye to prevent infection and inflammation. It’s a good idea to rest for the remainder of the day after your surgery.

The day after the procedure, your eyes will be checked and you may be given more drops to promote healing. Due to increased light sensitivity you may also need to wear protective sunglasses while outdoors.

After multifocal lens implants

You should be able to resume your normal activities with a day or so after your procedure, but avoid heavy lifting or rubbing your eye. Complications following the implant surgery are rare, but can include infection, bleeding, and retinal detachment. People with diabetes, high blood pressure, and chronic infections are at higher risk for complications.

For the first few days after the procedure, your distance vision should be clear. You might experience blurry intermediate or near vision until your visual system adapts to your new multifocal lens implants. Lens implants are usually implanted in one eye at a time. After the first eye has healed the second implant procedure is performed. With multifocal lens implants most people find their ability to adapt to the intermediate and near focusing characteristics of the lens is much better after both lenses have been implanted. Some people find they need reading glasses for close up viewing during the short healing and adjustment period.

Although your vision should improve with the implant, your eyes might take several months to reach their full focusing potential. Reading and viewing objects up close without wearing glasses can help strengthen your eyes. Because everyone’s eyes are different, some patients will not be able to see 20/20 at all distances without glasses.

Phacoemulsification

A small incision is made using special micro surgery tools. Your surgeon will removal a small cap from the lens capsule. Like a grape, your natural lens has an inner material (nucleus) and an outer skin (capsule). Next, using a special phacoemulsification probe, the exposed nucleus is removed using gentle ultrasound waves. Ultrasound reduces the material into small particles that can be aspirated through the “phaco” probe. Removal of the nucleus in this manner leaves the capsule in place to act as a container to hold the new lens implant.

How Do Multifocal Lens Implants Work?

ReZoom and ReSTOR Multiple Optical Zone IOL’S

Multifocal IOL’s with multiple optical zones have a series of concentric focusing rings extending from the center of the lens to the lens periphery. Each ring section has it own focusing power and corresponding focal point. With these lens designs distant vision is very good right after surgery but intermediate and near vision may be blurry during the healing period. Over a short adjustment period the brain learns to “look” through the best area of the lens to provide good distant, intermediate or near vision as required by the object of attention.

ReZoom Multifocal IOL

The ReZoom IOL has 5 focusing zones. The zones are designed to give good distance, intermediate and near vision in a variety of bring or dim lighting conditions.

AcrySof Restor Multifocal IOL

The AcrySof ReStor IOL has 2 regions, a central region with 12 concentric rings with apodized (gradually decreasing or blended) step heights and a peripheral refractive region dedicated to distance vision. The peripheral region is also designed to enhance distance vision under dim light conditions.

Crystalens Hinged IOL

The crystalens IOL uses the eyes zonules and ciliary body muscles to move the lens either forward or backward to adjust the focal point for good vision. Relaxation and contraction of the Ciliary Muscle (a.) results in either an increase or decrease in the tension of the zonules holding the lens capsule and crystalens IOL. This change in tension causes the lens implant to move either forward (b.), or backward (c.), adjusting the focal point for clear near vision or clear distance vision. With this lens design distant vision is good right after surgery, and over time, the brain learns how to manage the zonule and ciliary muscle combination to control movement of the crystalens IOL and provide good distant, intermediate or near vision as needed.

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