CATARACTS

Your eye works a lot like a camera. Light rays focus through your lens on the retina, a layer of light sensitive cells at the back of the eye. Similar to film, the retina allows the image to be "seen" by the brain. But over time the lens can become cloudy and prevent light rays from passing clearly through the lens. This cloudy lens is called a cataract.

The typical symptom of cataract formation is a slow, progressive and painless decrease in vision. Other changes include: Blurring of vision, glare, particularly at night, frequent eyeglass prescription change, a decrease in color intensity, a yellowing of images and in rare cases, double vision.

Normal lens versus a cataract lens.

Blurring of Vision

This picture stimulates blurry vision as seen through cataract lenses.

Decrease in color intensity

The picture on the left stimulates vision through normal lenses. The picture on the right stimulates the decrease in intensity of colors as viewed through cataract lenses.

The picture on the left stimulates vision through normal lenses. The picture on the right stimulates the yellowing of vision experienced through cataract lenses.

Ironically as the lens gets harder, farsighted or hyperopic people experience improved distance vision and are less dependent on glasses. However, nearsighted or myopic people become more nearsighted or myopic, causing distance vision to be worse. Some types of cataracts affect distance vision more than reading vision. Others affect reading vision more than distance vision.

A cataract is a loss of transparency, or clouding, of the normally clear lens of the eye. The lens lies behind the iris and the pupil.

Diagram of the eye

It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away. The lens is made of mostly water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.

Diagram depicts the focusing power of a normal lens.

A normal human lens focuses light clearly on the retina. But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see.

A cloudy lens (Cataract) keeps light from focusing clearly on the retina.

Researchers suspect that there are several causes of cataract, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years.

In a normal eye, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain. The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image you see will be blurred.

As one ages, chemical changes occur in the lens that make it less transparent. The loss of transparency may be so mild vision is hardly affected or so severe that no shapes or movements are seen, only light and dark. When the lens gets cloudy enough to obstruct vision to any significant degree, it is called a cataract. Glasses or contact lenses cannot sharpen your vision if a cataract is present.

The most common cause of cataract is aging. Other causes include trauma, medications such as steroids, systemic diseases such as diabetes and prolonged exposure to ultraviolet light. Occasionally, babies are born with a cataract.

Reducing the amount of ultraviolet light exposure by wearing a wide-brim hat and sunglasses may reduce your risk for developing a cataract, but once developed there is no cure except to have the cataract surgically removed. Dr. Najafi-Tagol can perform surgical procedures to remove the cataract through either a small incision (phacoemulsification) or a large incision (extracapsular extraction). The time to have the surgical procedure is when your vision is bad enough that it interferes with your lifestyle.

Presbyopia is a condition experienced by many individuals starting around age 40. When a patient diagnosed with presbyopia is young, the lens inside the eye changes shape to focus at different distances–allowing a full range of vision.

Diagram depicts presbyopia.

Gradually the lens loses it ability to change shape and focus at different distances. Bifocals and trifocals become necessary to see distant, near and intermediate objects.

The only way to eliminate the symptoms of a cataract is to have the natural lens removed and replaced with an intraocular lens (IOL). However, by choosing a Multi-focal IOL to replace your cataract, you can enjoy a full range of vision, decreased dependency on glasses, and a dramatically reduced need for bifocals or trifocals.

Cataract surgery

Cataract surgery is a very successful operation. One and a half million people have this procedure every year and 95% have a successful result. As with any surgical procedure, complications can occur during or after surgery and some are severe enough to limit vision. But in most cases, vision, as well as quality of life, improves.

The common visual side effects of Multifocal IOL lenses is halos (rings) around lights at night.

However:

• Degree of side effect varies with each patient
• Most noticeable during first few months after procedure
• Should not impair the ability to function at night

The first step is to determine if ReSTOR™, Crystalens™ or Rezoom™ Multifocal IOL is right for you with a complete eye examination.

Extracapsular cataract extraction is a method for surgically removing a cataract.

Extracapsular Cataract Extraction

In extracapsular cataract extraction, an incision is made in the side of the cornea at the point where the cornea and sclera, the white part of the eye, meet. Carefully entering the eye through the incision, the surgeon gently opens the front of the lens capsule and removes the hard center, or nucleus, of the lens.

The soft lens cortex is then suctioned out leaving the back of the capsule in place.

An incision requiring sutures is necessary because the lens is removed in one piece. A plastic implant called an intraocular lens, or IOL, is substituted for the original lens.

The implanted IOL allows light to be focused on the retina.

It may be up to six weeks before the sutures are removed and best-corrected vision is achieved. During recovery, it may be necessary to avoid bending over or lifting heavy objects. Side effects include a decrease in color intensity, a yellowing of images and in rare cases, double vision.

Phacoemulsification is a surgical method used to remove a cataract. In phacoemulsification, an ultrasonic oscillating probe is inserted into the eye.

Phacoemulsification

The probe breaks up the center of the lens. The fragments are suctioned from the eye at the same time. A small incision that often does not require sutures to close can be used since the cataract is removed in tiny pieces. Most of the lens capsule is left behind and a foldable intraocular lens implant, or IOL, is placed permanently inside to help focus light onto the retina. Vision returns quickly and one can resume normal activities within a short period of time.

An intraocular lens (IOL) is a tiny, lightweight, clear plastic disk placed in the eye during cataract surgery. An IOL replaces the focusing power of the eye's natural lens.

Intraocular Lens

The lens of the eye plays an important role in focusing images on the retina. If the lens loses its clarity, as it does when a cataract develops, light rays do not focus clearly and the image one sees is blurry. Glasses or contact lenses cannot sharpen vision if a cataract is present.

The only treatment for a cataract is to remove the lens and implant an IOL. Intraocular lenses have many advantages. Unlike contact lenses, which must be removed, cleaned and reinserted, the IOL remains in the eye after surgery.

An IOL may be placed either in front of or behind the iris. Behind the iris is the most frequent placement site.

Intraocular Lens

They can be hard plastic, soft plastic or soft silicone. Soft, foldable lenses can be inserted through a small incision, which shortens recovery time following surgery.

Rapid evolution of IOL designs, materials, and implant techniques have made them a safe and practical way to restore normal vision after cataract surgery.

Different Choices of IOLs

IOLs come in all shapes, sizes, and powers and can correct pre-existing nearsightedness and farsightedness.

Mono-focal IOLs

• Until recently–monofocal IOLs were widely used
• These provide only one point of focus – usually distance
• Spectacle correction required for near and intermediate visual activities

Multi-focal IOLs

• Provides a full range of vision
• Decreases dependency on glasses
• Dramatically reduces the need for bifocals or trifocals

For most patients, multi-focal vision means you can see to read a menu (near), work on a computer (intermediate), and see the building across the street (distance).

A posterior capsulotomy is a surgical laser procedure that may be necessary after cataract surgery.

During cataract surgery part of the front (anterior) capsule that holds the lens is removed. The clear back (posterior) capsule remains intact. As long as that capsule stays clear, one has good vision. But in 10 to 30% of people, the posterior capsule loses its clarity. When this happens, an opening can be made in the capsule with a laser (posterior capsulotomy) to restore normal vision.

Posterior Capsulotomy

Although most cataracts occur in older adults, they can appear in children, in one or both eyes, often at birth. They look like a white or gray spot in the pupil.

Cataracts in children may be inherited or develop because of an infection or a disease acquired before birth, or as a result of an injury. In most cases, no specific cause is found.

Children may lose vision permanently because of amblyopia (lazy eye) if a severe cataract is not removed quickly. The better eye may also need to be patched. Mild cataracts may not need treatment.

The focusing power of the original lens, removed during cataract surgery, must be replaced to restore vision. Intraocular lenses (IOLs), permanent plastic lenses placed inside the eye, are implanted in older children much as they are in adults. In infants, IOLs are controversial because the eyes grow and change their prescriptions during the first few years of life. Many surgeons prefer contact lenses or even glasses for younger children.

Regardless of the type of correction, children need follow-up exams to avoid possible complications, including glaucoma, scar tissue forming in the pupil and amblyopia. Often, children will need eye muscle surgery because the eye turns or crosses.

Despite these problems, cataracts are the single most treatable cause of childhood blindness. After surgery, most children can see the blackboard in school (20/60-20/100). While some do not do as well, with appropriate correction, many children see almost normally.