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WHAT IS A MIGRAINE?
Migraine headaches, sometimes preceded by warning symptoms, can have specific triggers but also can vary in severity and type.
As distinct from the tight band type tension headache and the cluster headache often around one eye, the classic migraine is on one side of the head with the vision effected. Migraine is a common headache disorder with no conclusive cures, of many types affecting about 15 per cent of the population, but much is underdiagnosed and can have serious health risk warnings eg women suffering from migraine with aura at any age should never use oral contraceptives accordingly.
A diagnosis of migraine is one of exclusion. especially in recent onset cases, increasing severity/frequency, neurological symptoms of pins and needles and visual field defects all indicate further work up is indicated eg MRI with a neurologist or neuro-ophthalmologist
Migraine can be triggered by many factors such as food, medication,weather, stress, lack of sleep, skipping meals, dehydration. Triggers need to be kept in a diary,ideally.
WHAT CAUSES MIGRAINES ?
WHAT CAUSES MIGRAINE PAIN ?
Researchers have identified more than 20 irregular chromosome segments associated with migraine. Each potential genetic error affects how nerve cells work in a different way. The most effective treatments control the individuals triggers for migraines often called predisposing and precipitaing factors.
The brainstem is a complex intersection of nervous system wiring at the base of our brain in clusters of cell bodies called nuclei. From these nuclei, new signals are rerouted to other parts of the brainstem and the rest of the brain.These nuclei control pain, stress, balance, mood, sleep and the autonomic nervous system.
MEDICAL FILTERS
The FL-41 tint has been used successfully for migraine sufferers and in certain neurological conditions.
READ MORE
At 75% luminous transmittance or 25% absorption as an over the counter sunglass category 2 (43% to 80% luminous transmittance) it would have to be marked
“Not suitable for driving at twilight or night” or “Not suitable for drivng at night or under conditions of dull light”
Traffic signal visibility requirement must also be met for OTC and prescription. If they don’t then they must be marked “Notsuitable for driving and road use”
If they are considered precription, then AS/NZS ISO 8980-3 applies,
6.3.4 Driving in twilight or at night refers spectacle lenses with a luminous transmittance less than 75% shall not be used for driving in twilight or at night.
Medical filters are dyed according to the transmission curve
MEDICAL FILTER LENSES can be used for
• Age-related macular degeneration
• Albinism
• Diabetic retinopathy
• Retinitis pigmentosa
• Achromatopsia (colour blindness) Migraines
• Cone-rod-dystrophy
• Iris coloboma
• UV protection for pseudophakia and aphakia
• Photochemotherapy,
Medical filter lenses absorb short-wave blue light components more strongly than conventional sun protection lenses or contrast-enhancing lenses. Medical filters lenses can restrict peripheral vision due to the (almost) complete absorption of short-wave blue and violet light – which is extremely important in sports.
The short-wave violet and blue light causes scattering in the eye, which leads to glare and a reduction in acuteness of vision.
The contrast is increased by the difference between the strongly and less strongly exposed receptors.
Visual symptoms such as blurred vision, visual aura and photophobia can occur during migraine attacks, but not necessarily always.
Less than half of current migraine sufferers have been formally diagnosed, and about one-third are thought to receive appropriate treatment with prescription medications.
Colourimeter research data determines certain specific tints can help migraine sufferers whose migraines are triggered by pattern glare.
BPI manufactures the pink FL-41 dye is a mixture of colours that blocks the blue-green wavelengths.
BPI is the world’s largest manufacturer of optical tints.
Though the efficacy of Blue Light Blockers can vary, environmental exposure to blue light, including those from digital screen technology, does not cause significant damage to eyesight. Therefore, filtering out the blue light from screens is not essential but can be helpful.
The FL-41 tints in 25, 50 and 75% transmissions. (The % related to how dark the tint saturation is.) are sometimes prescribed for patients with migraine or brain trauma.
Research shows that there is not one specific colour to treat migraine (or any condition) as peoples vision and brains react differently and need to be treated individually. This is the reason the Colorimeter has 110,000 different colour combinations.
Pattern glare tests involve tints (that later can be prescribed) often but not always blue or yellow to reduce nausea that can arise from stripe patterns for some people by reducing or changing the contrast between black and white.
The theory is some people have a hyperactivity imbalance between their central and peripheral vision for light, flicker and specific spatial frequencies in stripes and patterns and can make reading difficult.
Optometrists do not treat “dyslexia” or even learning difficulties, but learning-related vision problems, and in the above cases treat people with pattern glare with tints when it affects reading.
Migraine is a complex and the most common neurological condition and classified by the World Health Organisation as the 7th most disabling disease worldwide, the 4th for women. It is three times more common in women than it is in men and is usually inherited. It is a very individual condition. Some people experience only an odd attack, while others suffer them regularly
TYPES OF MIGRAINES
RETINAL MIGRAINE
A retinal migraine (aka ophthalmic, migraine, visual, ocular ) has the temporary loss of vision effect by definition. (A headache that lasts from 4 -72 hours.)
An aura usually appears in both eyes.
Retinal migraines involve episodes of temporary vision loss or blindness in one eye only.
A retinal migraine often comes on suddenly in concert with head pain and nausea from a vascular spasm in or behind an eye.
Retinal migraines are apparent in 1 in 200 migraine sufferers with short-term loss of vision in one eye only.
• flashing lights or haloes
• blind spots in your field of vision
• partial or complete blindness
• affect one side of the head
•painful
• aggravated by activity
• nausea and vomiting
• sensitivity to light/sound
MIGRAINE WITH AURA
Aura :
Blind spots
Flashing lights
Zig-zag patterns
Pins and needles on one side usually starting in the fingers/ arm, sometimes spreading up into the face.
Slurring of speech
Muscular weakness
Loss of co-ordination
Confusion) up to an hour duration can occur in about 20% of cases before the actual headache.
The actual headache:
Intense throbbing headache, usually on one side of the head, worsened by movement and lasting from 4-72 hours.
Nausea, sometimes vomiting.
Sensitivity to light, noise, smells, Stiffness of the neck and shoulders, Blurred vision.
MIGRAINE WITHOUT AURA
Most commonly, migraine occurs without the aura but with the headache
The intense throbbing headache, usually on one side of the head, worsened by movement and lasting from 4-72 hours.
Nausea, sometimes vomiting
Sensitivity to light, noise, smells
Stiffness of the neck and shoulders.
Blurred vision
MIGRAINE WITHOUT HEADACHE
Occasionally migraineurs can experience only the aura of
Blind spots
Flashing lights
Zig-zag patterns
Pins and needles on one side usually starting in the fingers/ arm, sometimes spreading up into the face.
Slurring of speech
Muscular weakness
Loss of co-ordination
Confusion
OPTHALMOPLEGIC
As well as the headache occurring mainly in young people, there is the weakness of one or more of the muscles that move the eye, dilate the pupil and control the eyelids.
BASILAR
Rarely in young women, mainly loss of balance, double vision, blurred vision, difficulty in speaking and fainting.
Headache, loss of consciousness. Basilar migraine occurs when the circulation in the back of the brain or neck is affected.
HEMIPLEGIC
It is rarely headache but with temporary numbness, weakness, or even paralysis on one side of their body up to a few days in duration.
MRIs, CT scans and other neurological tests are required to rule out stroke, blood clot stroke, pituitary tumour, detached retina, or drug abuse.
Treatment causes etc
Acute medications used include the normal NSAIDs such as Ibuprofen,anti-nausea medication as well as preventative medications.
VESTIBULAR
Many migraine sufferers experience some vestibular symptoms during their lifetime, such as dizziness, sensitivity to light/sound and stiffness of the neck
but severe vestibular migraine can encompass
Severe dizziness
Vertigo
Sensitivity to light, sound, smell
Nausea and vomiting
Ataxia (loss of control over bodily movement)
Neck pain
Muscle spasms in the upper spine area
Confusion
At 75% luminous transmittance or 25% absorption as an over the counter sunglass category 2 (43% to 80% luminous transmittance) it would have to be marked
“Not suitable for driving at twilight or night” or “Not suitable for drivng at night or under conditions of dull light”
Traffic signal visibility requirement must also be met for OTC and prescription. If they don’t then they must be marked “Notsuitable for driving and road use”
If they are considered precription, then AS/NZS ISO 8980-3 applies,
6.3.4 Driving in twilight or at night refers spectacle lenses with a luminous transmittance less than 75% shall not be used for driving in twilight or at night.
Medical filters are dyed according to the transmission curve
MEDICAL FILTER LENSES can be used for
• Age-related macular degeneration
• Albinism
• Diabetic retinopathy
• Retinitis pigmentosa
• Achromatopsia (colour blindness) Migraines
• Cone-rod-dystrophy
• Iris coloboma
• UV protection for pseudophakia and aphakia
• Photochemotherapy,
Medical filter lenses absorb short-wave blue light components more strongly than conventional sun protection lenses or contrast-enhancing lenses. Medical filters lenses can restrict peripheral vision due to the (almost) complete absorption of short-wave blue and violet light – which is extremely important in sports.
The short-wave violet and blue light causes scattering in the eye, which leads to glare and a reduction in acuteness of vision.
The contrast is increased by the difference between the strongly and less strongly exposed receptors.
Visual symptoms such as blurred vision, visual aura and photophobia can occur during migraine attacks, but not necessarily always.
Less than half of current migraine sufferers have been formally diagnosed, and about one-third are thought to receive appropriate treatment with prescription medications.
Colourimeter research data determines certain specific tints can help migraine sufferers whose migraines are triggered by pattern glare.
BPI manufactures the pink FL-41 dye is a mixture of colours that blocks the blue-green wavelengths.
BPI is the world’s largest manufacturer of optical tints.
Though the efficacy of Blue Light Blockers can vary, environmental exposure to blue light, including those from digital screen technology, does not cause significant damage to eyesight. Therefore, filtering out the blue light from screens is not essential but can be helpful.
The FL-41 tints in 25, 50 and 75% transmissions. (The % related to how dark the tint saturation is.) are sometimes prescribed for patients with migraine or brain trauma.
Research shows that there is not one specific colour to treat migraine (or any condition) as peoples vision and brains react differently and need to be treated individually. This is the reason the Colorimeter has 110,000 different colour combinations.
Pattern glare tests involve tints (that later can be prescribed) often but not always blue or yellow to reduce nausea that can arise from stripe patterns for some people by reducing or changing the contrast between black and white.
The theory is some people have a hyperactivity imbalance between their central and peripheral vision for light, flicker and specific spatial frequencies in stripes and patterns and can make reading difficult.
Optometrists do not treat “dyslexia” or even learning difficulties, but learning-related vision problems, and in the above cases treat people with pattern glare with tints when it affects reading.
Migraine is a complex and the most common neurological condition and classified by the World Health Organisation as the 7th most disabling disease worldwide, the 4th for women. It is three times more common in women than it is in men and is usually inherited. It is a very individual condition. Some people experience only an odd attack, while others suffer them regularly
The post Migraines and Eyes appeared first on Peter D'Arcy Optometrist.
]]>The post Colour Vision Testing appeared first on Peter D'Arcy Optometrist.
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Colour vision defects can be tested by recording discriminated patterns or numbers on the Ishihara colour vision plates, and sometimes further diagnosis occurs in specially equipped colour vision clinics. Defective colour vision is not ‘colour blindness and is common and inherited.
1 in 12 men (8 per cent)
1 in 200 women (0.5%)
Present at birth and remains unchanged.
There is no treatment, but different techniques to allow the colour to be inferred by brightness are being researched and developed. Sometimes tints can be used to select more specific wavelengths but will not cure colour vision defects. Typically greens, yellows, oranges and reds can be confused. It causes colour matching problems, colour naming problems and the inability to perceive the brightness of colours.
Colour blind glasses
Supposed colour blind glasses, often magenta, create a brightness difference, so even a person who perceives all colours as a single hue (a monochromat) would pass.
As many patients use screens much more than printed text, brightness changes and reversing contrast can help.
There have been many iterations of such glasses since they were first suggested by Seebeck (1817).
The first in contact lenses, X-Chrom, was by Harry Zeltzer (1971)
They are designed to perceive brightness differences as colour differences. One of the requirements of the Ishihara is that it is done under specific lighting without any filters.
HOW IS COLOUR VISION GRADED
Colour is used in schools for teaching purposes, so all children should have their colour vision tested. Children’s vision is fundamental to their learning.
Ishihara test, which is very reliable and only takes a few minutes.
> 3 errors mean fail. Follow up is necessary.
Defects can vary in severity. The Ishihara test doesn’t measure the extent of the defect. By preschool, a child may show signs of having problems recognising and identifying different colours.
While all unaffected individuals would see the number 74, colour defectives may see other numbers or no numbers.
4.5% of the population are colour defective, with males having an 8% colour defective rate.
The CIE chromaticity diagram represents all colours humans can perceive. The CIE system characterizes colours by a luminance parameter Y and two colour coordinates x and y
READ MORE ABOUT COLOUR VISION
Colour vision defects can be tested by recording discriminated patterns or numbers on the Ishihara colour vision plates, and sometimes further diagnosis occurs in specially equipped colour vision clinics. Defective colour vision is not ‘colour blindness and is common and inherited.
1 in 12 men (8 per cent)
1 in 200 women (0.5%)
Present at birth and remains unchanged.
There is no treatment, but different techniques to allow the colour to be inferred by brightness are being researched and developed. Sometimes tints can be used to select more specific wavelengths but will not cure colour vision defects. Typically greens, yellows, oranges and reds can be confused. It causes colour matching problems, colour naming problems and the inability to perceive the brightness of colours.Retinal cone photoreceptors, either contain red, green and blue responsive photopigments. These human eye cone cells can hundreds of shades, and millions of colours. Some rare individuals have a genetic mutation granting them an extra, fourth cone cell. Colour confusion line can be plotted on the CIE
The CIE 1931 RGB colour space and CIE 1931 XYZ color space were created by the International Commission on Illumination (CIE))
What causes colour vision defects?
Accidents and trauma to the retina or brain can cause defects, and acquired colour defects can be crucial in pathology diagnosis.
Nutritional causes such as deficiency of vitamin A and degenerative diseases of the eye – macular degeneration, glaucoma, diabetes and cataracts can all bear on the quality of colour vision.
Inherited colour blindness is the most common cause of loss or partial loss of the different cone systems within the eye due to missing or damaged genes.
Further tests are required to assess this provided by an optometrist, sometimes in specially equipped colour vision clinics featuring such equipment such as the Nagel anomaloscope, D15 test where hue samples are recorded and referenced in a juxtaposed fashion to a reference and the Farnsworth lantern.
The Ishihara test doesn’t measure the extent of the defect.
Further tests are required to assess this.
Follow up can be provided by an optometrist or ophthalmologist.
The rod cells are active in low light, and the cone cells (active in average daylight). A normal eye has three kinds of colour receptors.
For red, green and blue light, Responses are relayed to the brain.
Here they are mixed to perceive many thousands of colours.
Defects occur by:
One receptor is missing.
One receptor is abnormal.
Two or even three receptors are missing is a rarer and a more severe problem.
Colour vision and your job
Everyday problem examples of coping with a colour vision defect:
Recognising the colour of traffic lights.
Seeing coloured flowers on trees.
Judging ripeness of fruit.
Knowing when meat is cooked.
Job requirements where colour vision could be an issue
e.g. Airline pilot
Air traffic controller
Train and tram driver
Policeman
Fireman
Careers in the defence forces
Seafarer
What is the most common colour vision defect?
Red-green colour blindness is the most common type of colour defect because the genes that lead to red-green colour blindness are on the X chromosome, with males having just one X chromosome, whilst females have two.
Blue colour blindness is far less common, being present in just 5% of all colour blindness sufferers. The genes affected are equal in both sexes.
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