Post on 13-Jan-2016
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Migraine prevention using colour filters
Dr Yolande KnightGP ST2
Mid Sussex/Brighton VTS
Introduction
Introduction Concepts Basic migraine pathophysiology Cortical hyperexcitability Visual stress Precision spectral filters and ophthalmic tints
Evidence 'Seeing the light' Clinical application
Migraine pathophysiology- cortical excitability
www.CGRPinmigraine.com (Merck)
Migraine pathophysiology
Visual aura, photophobia
Visual triggers
Migraine pathophysiology- cortical hyperexcitability
www.CGRPinmigraine.com (Merck)
Migraine art-the perceptual experience of migraine
Visual stress- aversive art
Bridget Riley exhibition. Daily Telegraph (1971): guards complained of headaches and requested dark glasses
Visual stress-uncomfortable art
Least uncomfortable images
Most uncomfortable images
AJ Wilkins, 2006
Visual stress- aversive imagery from a migraineur's view
www.debbieaylesartist.co.uk
www.debbieaylesartist.co.uk
Visual stress- aversive imagery from a migraineur's view
Visual stress- visual environments
Pretty J, Peacock J, Sellens M and Griffin M. 2005. Int'l Journal of Environmental Health Research 15(5), 319-337
Text as a visual stressor
Pages of print can resemble visually stressful patterns
Visual stress-spatial frequency and threshold of discomfort
Some people find striped patterns uncomfortable to look at The discomfort depends on the spatial frequency of the
stripes
Spatial frequency: 3 cycles per degree
Degree of discomfort depends on individual susceptibility Migraineurs experience discomfort from patterns causing only
mild aversion in non-migraineurs, typically 3 cycles/degree
(AJ Wilkins, 2006)
Visual stress-symptoms and signs
Visual stress Also known as Irlens syndrome Co-morbid with migraine? Or a sub-symptom of migraine? Associated with dyslexia
Visual distortions Illusions of motion, shape, colour Reading difficulties
Physiological symptoms Eye strain Nausea Headache Seizures
Signs Using finger as a marker for reading Skipping words Excessive blinking
Visual stress-mechanism and manipulation
Mechanism Hyperexcitability in the visual cortex
Hypothetical manipulation Pattern of excitation in ophthalmic cortex neurons changes in
response to colour stimulus, either by direct stimulus of that colour or absorption of opposing colour
Which colour reduces hyperexcitability is 'specific to the individual'
Assessing visual stress-colorimetry
Intuitive Colorimeter projects coloured light onto a page of text found to be stressful or aversive to the migraineur
Manipulate hue and saturation to identify the most comfortable colour (of 100,000 possible colours)
Replace text with a stressful stripe pattern of 3cpd to test the effectiveness of this particular colour in reducing visual stress
POTs in practice
Cerium manufactures Precision Tinted Lenses (PTL) Spectacles Contact Lenses
Coloured Overlays Coloured plastic sheet to overlay on text
The effect of POTs on reading
Evidence -Precision Ophthalmic Tints (POT) in migraine
Wilkins et al. Cephalalgia 2011. N=11 migraineurs
9/11 h/o visual triggers for migraine 7/11 MwA 11/11 experienced illusions/distortions during study
fMRI Reduced cortical activation in V2 in migraineurs
wearing POT under visual stress visual discomfort score (/10)
8.0±2.1 without lens 2.4±1.7 with POT lens
Evidence -Coloured lenses in migraine
Huang et al. Cephalalgia 2002. N=17 migraineurs
12/17 MwA In 45% of MwA patients, headache frequency reduced by
50% or more on days when POTs were worn versus days wearing control colour lens
Afra et al. Headache 2000. Visual evoked potentials N=12 MwA vs controls Glasses in red, green, yellow, blue, grey No effect in MwA
Evidence - rose tinted spectacles...
Good et al. Headache 1991. 20 children with clinically diagnosed migraine Rose vs blue tint for 4 months After 4 months, those with rose tint had mean h/a
frequency improve from 6.2 episodes to 1.6 per month
Mechanism of light-sensitivity in migraine? Noseda R et al. Nat Neurosci. 2010
Posterior thalamo-cortical neurons that are both dura- and light-sensitive apposing photo-regulatory retinal ganglion axons
Seeing the wood for the trees
Pros Cons
Some supportive studies in migraineurs, albeit with small numbers
Field is dominated by 1 lead researcher (Wilkins) who also worked with Cerium and MRC to develop the Intuitive Colorimeter and lens specs.
No significant reported side effects of wearing colour lenses
RCTs are lacking
Does not require GP referral. Direct attendance at Optometrist
Within the Ophthalm field there is some scepticism about Irlen and her theories of visual stress
Low cost to the NHS: private payment American Academy of Paediatrics does not believe there is any scientific basis for the use of coloured lenses in children to treat 'visual stress' because “the method used to select the lens or filter colour has been highly variable,the colour selection has also shown considerable variability,and the test-retest consistency has been poor”
American Assoc of Optometrists and of Ophthalmologists believes there is no evidence for use of coloured lenses nor of a distinct Irlen syndrome entity
Information for patients
Wear the tinted glasses for all daily activities Cost
£55 each colorimetry test, performed twice before precision lenses made
£90 to make coloured lenses Total £200 Local variance in DLA/subsidized costs
Optometrists Check on the Cerium website for nearest specialist
Optometrist with an appropriate Intuitive Colorimeter www.ceriumoptical.com
Irlen support www.irlen.co.uk