# Cortical Hyperexcitability, Visual Stress, Visual Distortions & Hallucinations



## Dr B (Apr 23, 2014)

Striped patterns (i.e., gratings) with particular spatial frequencies (density of the stripes) are known to produce visual stress and discomfort, induce phantom visual distortions and somatic sensations in susceptible observers. These phenomena have been termed 'pattern-glare', are the result of increased visual stress, and are thought to reflect increased degrees of cortical hyperexcitability in the brain and be associated with visual distortions, hallucinations and aura. The idea is that the stripes over-stimulate pockets of neurons in the visual system - even more so if inhibitory neural processes are hampered in some way.

Pattern-glare effects have been shown to exist for Migraineurs with aura, Epileptics (photo-sensitive epilepsies), Anxiety / mood disorders, Dyslexics, Autistic spectrum disorders, Meares-Irlen syndrome, Sleep disorders, and some non-clinical hallucinating groups (out-of-body experiences). What is also interesting is that although cortical hyperexcitability may well show a general trend to be increased in these groups, its level can increase / decrease over time, like a wave function, depending on other internal and external stressors (poor sleep / anxiety / fever). The more increased it becomes, the worse it is for the individual and the likelihood of anomalous perceptions and possibly even seizure increases.

In our laboratory we are studying striped induced visual discomfort with non-clinical participants who show elevated signs of anomalous experiences. Effects of pattern-glare can be alleviated in some cases. For example, wearing tinted lenses can aid some groups. However, each person needs to have their visual system examined via what is known as an "intuitive colorimeter" in order to ascertain the maximally beneficial colour, saturation, hue of the tint. Tints do not work for everyone. Also the tints you may find helpful now, may not be helpful in about 5 years time. For reasons unknown, the type of tint most helpful can change over time.

If any of this is interesting to you, if you suffer from visual stress, pattern-glare, migraine, aura, or find bright light (sunlight / fluorescent lighting) or some patterns visually painful or irritating - then you may have visual stress which may require treatment. Note - there are sources of irritation in the natural environment that could trigger attacks or make current attacks worse. I would recommend the following. Avoid high-contrast environments (excessively bright lights / direct sunlight), avoiding being in spaces with uncomfortable visual patterns, have your computer monitor checked (it may be flickering just underneath the cusp of consciousness - this is still irritating your visual system), Flat screens may be more helpful, set the flicker rate to maximum. LED monitors set to low contrast. Avoid working under fluorescent lighting (it flickers and can be irritating / stressful to the visual system). Do you wear sunglasses all the time to help with your symptoms? If so, you may need to get coloured tints. Get your visual system examined by an opthalmologist for low-level ocular anomalies that can underlie many visual distortions. If all is OK, then get examined via intuitive colorimetry and see if you would benefit from a precision ophthalmic tint!


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## Dr B (Apr 23, 2014)

*Some further helpful information*

Braithwaite, J.J., Broglia, E., Brincat, O., Stapley, L., Wilkins, A.J., & Takahasi, C. (2013). Signs of elevated cortical hyperexcitability associated with spontaneous anomalous bodily experiences in the non-clinical population. Cognitive Neuropsychiatry. doi.org/10.1080/13546805.2013.768176.

Braithwaite, J.J., Broglia, E., Bagshaw, A.P, Wilkins, A.J. (2013) Evidence of elevated cortical hyperexcitability and its association with out-of-body experiences in the non-clinical population: New findings from a Pattern-Glare Task. Cortex. 49, 793-805.

Evans, B. J., Patel, R., & Wilkins, A. J. (2002). Optometric function in visually sensitive migraine before and after treatment with tinted spectacles. Ophthalmic and Physiological Optics, 22, 130-142.

Evans, B. J. W., & Stevenson, S. J. (2008). The pattern glare test: A review and determination of normative values. Ophthalmic and Physiological Optics, 28, 295_309.

Wilkins, A. J. (1995). Visual stress. New York, NY: Oxford University Press.

Wilkins, A. J., Baker, A., Amin, D., Smith, S., Bradford, J., Boniface, S., . . . Fish, D. (1999). Treatment of photosensitive epilepsy using coloured filters. Seizure, 8, 444_449.

Wilkins, A. J., & Evans, B. J. W. (2001). Pattern glare test. London, UK: IOO Marketing Ltd.

Wilkins, A. J., & Nimmo-Smith, M. I. (1984). On the reduction of eye-strain when reading. Ophthalmic and Physiological Optics, 4, 53_59.

Wilkins, A. J., Nimmo-Smith, M. I., Tait, A., McManus, C., Della Sala, S., Tilley, A., . . . Scott, S.(1984). A neurological basis for visual discomfort. Brain, 107, 989_1017.

Wilkins, A. J., Patel, R., Adjamian, R., & Evans, B. J. W. (2002). Tinted spectacles and visually sensitive migraine. Cephalalgia, 22, 711_719.

*Useful Google search terms:*

Visual stress
Cortical hyperexcitability
Pattern-glare

Intuitive colorimetry


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## Dr B (Apr 23, 2014)

If the OP is really interesting to you - (because you recognise the symptoms) - you need to see an opthalmologist or similar eye-specialist who possess an intuitive colorimeter and can give an eye exam.

Ask to be assessed for tints. Describe your symptoms. Note, standard opticians will not have these devices (unless you're lucky) and visual stress (per-se) will not show up on standard eye tests. Its a specific thing.

Another way is to do a pattern-glare test (viewing of striped patterns) - this will probably mean a trip to a university or research centre assuming someone is there with an interest in pattern-glare. Visual stress can come and go as the background excitability of the cortex varies (rises and falls). You still have it, even if the symptoms have temporarily lessened to some degree. We had one instance where we were measuring visual stress in one migraine patient every day for 2 weeks and 24hrs before a severe attack, their hyperxcitability had increased a great deal relative to the other days of testing....something in the brain was changing (affecting visual stress, irritability and hyperexcitability) 24hrs before a migraine attack with aura. There were no other signs that a storm was brewing....


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## Dr B (Apr 23, 2014)

And this is what a colorimeter looks like.


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## Dr B (Apr 23, 2014)

The lenses


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## Dr B (Apr 23, 2014)




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## Dr B (Apr 23, 2014)

One final point. Do not go to what is known as an 'irlen practioner' using the irlen method - its not the same thing, and is not regarded as being scientific. They will also charge you a fortune for tinted lenses, and there is no evidence that their method works (and could make things worse).

Remember, get examined by a professional vision expert and get examined with an 'intuitive colorimeter'.

An assessment may cost between £60 - £80 and tinted lenses around £220 (UK prices).


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## Guest (Jan 11, 2015)

Wish I could afford this. I deal with the pattern glare effect and ocular migraines w/ aura, triggered by patterns on my shirt/curtains and fluorescent lights respectively. Sunglasses seem to ameliorate symptoms, so possibly tinted lenses would be a better alternative for everyday use.


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## Dr B (Apr 23, 2014)

Yes, its interesting isnt it. I've spoken to many people (with dissociation and DPD) who say that they use sunglasses to help with bright lights. However, these turn the light down across the entire spectrum and just make everything dull and harder to see. Its a kind of 'using a sledgehammer to open a walnut' sort of a thing. It works, but brings with it a lot of 'overkill'. There can also be problems during the evening and when driving.

The optimal solution is to be examined for POTs (precision opthalamic tints). However, please be aware - they don't work for everyone. My hunch is they will work more for those of you with migraine, or derealization.


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## Dr B (Apr 23, 2014)

Bump....using this now with DPD at sub-clinical levels with a double-blind trial. Its working!


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## TDX (Jul 12, 2014)

> Bump....using this now with DPD at sub-clinical levels with a double-blind trial. Its working!


Reference? And what exactly is it doing?


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## Dr B (Apr 23, 2014)

As said above, its working - that is to say, its ongoing, not finished yet we want a larger sample.

We are finding that POTs (Precision Opthalmic Tints) (and not placebos) are helping to reduce visual symptoms (irritation, aversion, visual distortions) for those scoring higher on measures of dissociation and DP. Its early days, but working really well. 

it wont work for everyone....

I've met a number of DP patients that 'self-medicate' with sunglasses....which, years ago, got me thinking...


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