Visual Control for Photosensitive Epilepsy.
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This information is provided to assist patients with Photosensitive Epilepsy and their carers to understand the possible benefits of Zeiss Claret Z1 F133 spectacle lenses in managing their condition. please discuss this with your Neurologist or Medical Practitioner as to whether these spectacle lenses may assist your particular form of epilepsy.
In 2006 a paper was published in the journal Epilepsia
that examined the benefits that a commercially available tinted spectacle lens may have in managing seizures. The lens used in this study was the Zeiss Clarlet Z1 F133, and it showed a remarkable benefit in significantly reducing the Photosensitive Epilepsy in 75% of the 610 subjects assessed. This finding permits the possibility of providing additional or non-pharmacological method of controlling Photosensitive Epilepsy.
Zeiss Clarlet Z1 F133
The Zeiss Clarlet Z1 F133 spectacle lens is a deep blue coloured lens that transmits regulates the transmission of light across the visual spectrum. Primarily wavelengths in the blue and green portion of the visual spectrum are transmitted to varying degrees. Light in the yellow, orange and part of the red portion of the spectrum is blocked. The Zeiss Clarlet Z1 F133 spectacle lenses are manufactured in Zeiss’ precision tinting laboratories in Aalen, Germany where over 7000 lenses are produced daily for many practical and therapeutic uses.
The Zeiss Clarlet Z1 F133 spectacle lens is cosmetically a similar density to a dark sunglass lens. It is not possible to lighten the colour of these lenses without affecting their spectrum of transmission. Patients will need to adapt initially to a blue cast over objects. However, once the initial adaption has passed more normal colour perception should be achieved. Educators of patients who wear Zeiss Clarlet Z1 F133 spectacle lenses should be counselled that patients wearing these special spectacle lenses may have some difficulty perceiving certain colours. Therefore special consideration may be required to ensure that educational information is not missed in visually orientated presentations.
Alternative Lens Tints
Alternative tint systems have been suggested including a liquid tinting preparation from BPI called Deep Blue Zee. It is worth noting that the transmission spectrum from this liquid tint is different from that of that of the Zeiss Clarlet Z1 F133. Additionally, precision tinting is not easily achieved in a normal optical lens laboratory setting. Careful control of timing and temperature are required to produce spectacle lenses of the required transmission spectrum. Therefore these products, whilst they may benefit some wearers, are not equivalent to the Zeiss Z1 F133 spectacle lenses.
Considerations in Manufacture
The use of the Zeiss Z1 F133 spectacle lenses in Photosensitive Epilepsy requires that there be minimal visible gaps around the edge of the spectacle frames when worn.
For this reason it is advised that a slightly curved, large sunglass type frame is used. It is advisable to utilise a spectacle frame that can be easily re-purchased for this purpose as it is more likely that a child will damage or break the spectacle frames before they damage the spectacle lenses. By using an easily obtainable frame of consistent manufacturing quality the existing Zeiss Z1 F133 lenses can be transferred to a new frame without re-manufacture of the lenses.
David Stephensen Optometrist can supply suitable spectacle frames, or provide advice as to which frames will be suitable for use.
For patients outside the Brisbane Metropolitan Area we can liaise to supply demonstration or sample frames to trial at home. Careful consideration of the appropriate frames is important in maximising the beneficial effects of the Zeiss Z1 F133 spectacle lenses in assisting patients with Photosensitive Epilepsy.
FOR FURTHER INFORMATION PLEASE CONTACT:
DAVID STEPHENSEN OPTOMETRIST
197 Beaudesert Road, Moorooka, QLD 4105
PHONE: +61 7 3848 8979