Seizure protection in a bottle!

With this blue tint, opticians can apply effective photosensitive seizure protection to plastic lenses.

If your local optician can tint eyeglasses, it’s now possible to get protection from visually triggered seizures without ordering therapeutic Zeiss lenses. Lenses tinted using the new Deep Blue Zee lens tint are nearly the same color and appear to be just as effective as Zeiss Z1 F133 lenses.

Brain Power Inc. of Miami, and its UK arm, Brain Power Ltd. of Warwickshire, England, have introduced a cobalt blue optical tint that, according to the company, is nearly identical to the color-filtering specifications of the Z1 F133 lenses used in Capovilla’s photosensitivity studies. Brain Power, which supplies optical tints and laboratory equipment to opticians, optometrists, ophthalmologists, and lens manufacturers, developed the Deep Blue Zee tint specifically for photosensitivity protection. BPI describes itself as the world’s largest manufacturer of optical tints, chemicals, and instruments.

My daughter has been wearing a locally tinted pair for the past week and is finding them quite effective. She actually prefers them to the Zeiss because they aren’t quite as dark and therefore don’t darken her entire view as much. Because they’re not as dark, she is still able to see when watching DVDs from farther away from the screen.

The therapeutic properties of the Z1 F133 lens are due to its color and the way it blocks out shades of red. The amount of light a lens lets in across the color spectrum is measured by a spectrometer and shown in a spectrum curve (see graphs below), and each lens color has a unique spectrum curve. Capovilla and colleagues tried many colors and lens types before settling on the cobalt blue shade that lets in very little light in the red part of the spectrum. The big dip in this graph, excerpted from Capovilla’s 2006 study, shows that very little light is transmitted through the lens in the range of red wavelengths, measured in nanometers.

This is the Z1 spectrum curve from the Capovilla studies:

BPI set out to make a tint with the same light transmittance properties.  As the spectrum curve of Deep Blue Zee shows, it’s very close to the Z1 specifications in keeping out red wavelengths:

For the tint to be absorbed properly by the lens, the lens needs to be made of a particular plastic lens material, a plastic called C-39. If you have existing lenses you’d like tinted, they need to be made of CR-39 and can’t already have a hard coating that would prevent the lens from absorbing tint. BPI recommends that the lens be kept in the dye solution for at least 30 minutes to achieve the proper color. According to BPI, after half an hour of immersion in the dye, the absorption process goes more slowly.

As we’ve discovered in the past week, although the locally tinted ones weren’t as dark as the Zeiss lenses, it doesn’t seem to matter. If the lenses turn out not as dark as you’d like, your optician can make them darker by returning them to the dye solution for a little while. The price for tinted lenses will vary depending on the brand/quality of lens that your optician uses. And the quality and effectiveness may vary as well, depending on the optician’s skill, judgment, and choice of lens manufacturer.

The optician who tinted Alice’s blue lenses is:

Paul Dimos, owner

Eye Look Optical
1760 Massachusetts Ave
Lexington, MA 02420

phone: 781-862-4510
fax: 781-674-0366

The same day we got the new clip-ons, I had the idea that Alice might be able to watch certain DVDs (no anime!) on a small screen without needing to take so many breaks. She is doing well watching DVDs on a portable 7-inch DVD player. She sits several feet away from it so that the screen doesn’t take up too much of her field of vision. If she sat very close, that would cancel out the advantage of a small image that by its size minimizes the impact of video on her brain.

We now have a spare pair of cobalt blue clip-ons, allowing us the opportunity to compare the two side by side. Can you tell which is which?

One pair from Zeiss and the other tinted by our optician.

Not a pretty picture: Z1 photosensitivity lenses disappear [updated]**

preventing video game seizures with protective Z1 glassesIn 1999 Italian researchers led by Giuseppe Capovilla published a study documenting their development of a special blue lens that showed great promise for protecting people sensitive to flashing light. The lens was manufactured for the researchers by the optics giant Zeiss and was given the name Z1. The Z1, which is a lovely shade of cobalt blue, blocks a great deal of the total incoming light. In addition it filters out the longer red wavelengths that are most likely to provoke seizures in those with photosensitivity. Ordinary polarized sunglasses, which some patients find helpful, don’t do this.

When wearing the Z1 lens, 77 percent of the photosensitive people in the study no longer showed any abnormalities on their EEG when exposed to flashing light. An additional 19 percent of study participants showed reductions in their abnormal EEG response. But it was a small study that involved only 83 participants.

When Capovilla and colleagues published a larger, follow-up study of 610 photosensitive individuals in 2006, they replicated these remarkable results. In the larger study, EEG abnormalities during exposure to flashing light disappeared in 463 (75.9%) of the participants, and the EEG abnormalities were considerably reduced in an additional 109 (17.9%). A mere 6.2 percent of the study participants experienced no change. Pretty impressive numbers. The authors concluded:  “The Z1 lens is highly effective…in a very large number of photosensitive epilepsy patients irrespective of their epilepsy or antiepileptic drug treatment. The lens might become a valid resource in the daily activity of any clinician who cares for patients with epilepsy.”

The Z1 lens has the potential to change lives, allowing those with photosensitivity to participate in everyday activities without constant fear of visual seizure triggers. These lenses are an attractive alternative to anti-epileptic drugs, which have many unpleasant and potentially serious side effects and which in many cases are not effective for photosensitivity.

But these therapeutic lenses aren’t available in the US.** For a time it was possible to obtain prescription glasses made with Z1 lenses. Here in the US some opticians connected with Canadian suppliers who ordered the glasses from Germany. Now, due to corporate restructuring and distribution changes at Zeiss, the Z1 is unavailable here. It’s not clear whether the lenses are still available in Europe, where the follow-up study said they were commercially available. Meanwhile, Zeiss is selling “portable eyewear” to deliver 3D viewing for Playstations, iPods, iPads, and other video-delivery devices. What’s wrong with this picture?

My attempts to contact Zeiss about the Z1 have not been successful. Anyone out there have information on this that you can share with us here?

**3/28/12 Note:  Thanks to responses from readers I have found several sources and my daughter has her new lenses! I recently posted quite a bit more about these lenses, including information on my daughter’s experiences with them and on how to order. Please see

**5/15/12 Note: Now there is also a cobalt blue tint for lenses, developed as an alternative to the Zeiss lenses, that we have found equally effective. See