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Everyone will develop cataracts, or clouding of the lens of the eye, as they age. The proteins in the human lens are arranged such that they are clear and allow light to pass through undisturbed. The most common cause of cataracts is aging, which results in the eventual degradation and breakdown of those proteins resulting in structural changes. These changes cause clouding and yellowing of the lens. Other common causes of cataract include family history, medical diseases such as diabetes, eye injuries, medications such as steroids and U/V light exposure. The typical forms of cataracts consist of nuclear sclerotic, cortical and posterior subcapsular.

The rate at which a cataract develops varies for each individual and can be different for each eye. The majority of age-related cataracts progress relatively slowly over a period of years and often are removed when the patient is in their late 60s, 70s or older. Diseases such as diabetes, or medications such as steroids, however, often results in cataracts at a younger age which may progress rapidly over short periods of time.

As cataracts become visually significant, the symptoms typically include a painless blurring of vision, glare or light sensitivity (especially with night driving), difficulty seeing at night or needing a brighter light to read, double vision in one eye and fading or yellowing of colors. Cataract changes often result in eyeglass prescription changes and the symptoms can sometimes be temporarily improved just with a change in eyeglasses.

Once these symptoms begin to interfere with a person’s ability to function or their activities of daily living and cannot be corrected with eyeglasses, it is time to consider treating them.

At this time, surgical intervention is the only treatment available for cataracts. Today’s most prevalent method of removing cataracts is with phacoemulsification technology. Ultrasound energy is used to break up the cataract into pieces which are then aspirated and removed from the eye with the same instrument. Once the cataract is removed, an artificial lens is implanted to provide the focusing power now needed.

The most common lens has been a monofocal, or fixed-focus lens, which will provide clear vision at a specific distance. This can be biased for distance vision or near vision, depending on the person’s needs or lifestyle. In order to see clearly, however, at all distances, some sort of eyeglass prescription is necessary. There is a vast array of choices and the actual lens used is usually determined by the surgeon’s preference. An example of one such lens is the AcrySof® Natural IOL.

The newest developments, however, in cataract surgery are offering some exciting alternatives for today’s cataract patients. As stated previously, the monofocal implant corrects one distance, either far or near, and glasses are needed to see at all distances. The newest lenses are either multifocal or accommodative lenses. These provide correction for myopia, hyperopia and presbyopia and may provide a spectacle-free lifestyle.

A multifocal intraocular lens is made up of concentric circles with areas of different focusing power and use either diffractive and/or refractive principles. The area of the lens being used determines the focus for distance and near. The fact that during accommodation, or reading, the pupils become smaller, results in using the central portion of the lens for near work and the outer portion for distance. Two common multifocal lenses available to patients today are the ReZoom™ lens by Advanced Medical Optics and the AcrySof® ReSTOR® by Alcon®, Inc.

The accommodative intraocular lens has an entirely different design. This type of lens is designed to move forward with accommodation to see objects at near and backward to see objects at distance. The Crystalens® by eyeonics™, Inc. is an example of an accommodating intraocular lens. The hinge design provides the flex point for the forward and backward movement.

The advantage to these lenses and what makes them exciting to today’s patients is the fact that over 75 percent or more of them, depending on the lens design, never have to wear glasses. Each lens design has its advantages and disadvantages and the lifestyle and activities of the patient can be used to determine which lens is most appropriate.

These various technologies are examples of what are available to today’s cataract patients who desire spectacle-free vision. This desire will continue to increase and the technologies will continue to improve and evolve to meet that desire.

Dr. Victor B. Thomas is a board-certified ophthalmologist with Eye Physicians of Central Florida.


July 2007

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