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Medical Use Contact Lenses

Contacts for Managing Seizures and Color Deficiency

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Updated March 25, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

When most people think about contact lenses, they think of them as devices used to improve their vision. But contact lenses are used for more than vision correction: sometimes contact lenses are used to treat or manage eye diseases and disorders. Doctors often refer to these lenses as medical-use contacts. These specialized lenses are fit the same way as standard contact lenses, but they are often made of different materials.

Two ways doctors are using contact lenses medically include the management of epileptic seizures and the improvement of color deficiency.

Contacts and Epileptic Seizures

Light sensitivity can be a major problem for people who suffer from epilepsy. Bright light can cause severe anxiety if a person is at risk of having reflex seizures, and regular sunglasses do not always help, and can be cumbersome to wear indoors.

But studies have shown that blue-tinted contact lenses may help reduce the photoparoxysymal or photoconvulsive response that some epileptic patients have. A photoparaxysymal response describes the abnormal brain activity that produces a response to light stimulation, flashes of light, or strobe lights that cause seizures. Blue lenses seem to be more effective than other colors. An ophthalmic company called Zeiss produces a lens called Z1 that is very effective at reducing this response.

Scientists are investigating exactly what type of wavelength should be blocked to reduce these types of abnormal reactions. In one study, a two-year-old suffering from severe epilepsy and seizures would have shock-like muscle contractions and jerks along with flickering hand and eyelid movements. Scientists tried various tinted lenses and found that some of the tinted lenses actually blocked many of the seizures. Their studies suggest that certain cells in the retina can be blocked to reduce seizures.

Contacts and Color Deficiency

Tinted contact lenses have also been shown to help people with color blindness. While true color blindness is rare, many people suffer from color deficiency. With color deficiency, different colors are detected but often confused.

In 1974, it was discovered that a red or magenta-colored lens fitted onto the non-dominant eye will almost always improve color differentiation on color vision tests. One of the most popular lenses for this type of problem is the X-Chrome lens, a red-tinted, rigid gas permeable contact lens worn on the non-dominant eye that seems to improve color perception in red-green color-deficient individuals.

Marietta Vision is a company that developed the ChromaGen lens system. This contact lens system offers several tints with different hues and densities that allow a doctor to select a certain tint that may perform better for certain individuals. The lenses can be worn on one or both eyes, and the tints are available in magenta, pink, violet, yellow, aqua, orange and green. In 2001, investigators studied this system in 14 color-deficient patients. The lenses not only significantly reduced color perception errors, but also made those patients feel that they had enhanced subjective color perception and improved function in everyday tasks that require color perception.

It is important to point out that these lenses do not restore perfect color vision by any means, but instead enable individuals to differentiate colors based off other light and color cues rather than true color discrimination. While these patients can now differentiate colors they previously had problems with, sometimes the lenses create new problems with other color pairs.

Source:

Szczotka-Flynn, Loretta. Tinted contact lenses for wavelength-specific treatments. Contact Lens Spectrum, Dec 2012, pages 10-11.

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