Visual Migraines

Both eyes are affected equally by visual effects of migraines, indicating a problem further into the brain than optic processing.

Three different types of visual disturbance occur, each triggered by different stimuli.

A central irregular polygon of nothingness is the start of the first type of apparition. This version of visual migraine tends to be triggered by a combination of stress and tiredness and often follows classical migraine headaches with vomiting. Luckily the visual effects follow the headaches. The size of the central nothingness might grow for some time, perhaps half and hour, and then disappear. It is an easy one to cheat, because the world can be seen around the edges of the central hole. The boundary of the central area is a polygon of straight but unpredictable sides. After some time the central nothingness fades away to reveal reality.

It seems that the best way to represent this of visual migraine in a painting is to make a conventional oil painting, then superimpose a small irregular polygon in a cold dark colour in the centre. Depicting it the size that it finally grows to makes a less interesting picture.

It is the deep thought image that is affected rather than a problem with retina or optic nerves because the effect is the same whether both eyes are used or whether one or other is covered.

The second type of problem is again deep in the visual processing. It is independent of which eye is used for viewing, or whether both are used. The central expanding polygon is very similar, but with a major difference. The boundaries of the polygon appear to be made of bands of scintillating and pulsating colour. These colours flow around the bands in irregular waves. The central part of the image is not nothingness, but it is a broken and distorted image of what should have been there. Looking for too long at tabular information on a computer screen commonly triggers this type of visual migraine. Spreadsheets are usually kept off my screen. Once the effect has been triggered, it continues for an hour so even when walking across the countryside.

These effects are different to those met by suffers of opthalmic migraine, which is a condition where the severe headache seems to be concentrated at the back of the eyes.

This type of visual migraine seems to be illustrated best with a watercolour painting. It has such a high degree of visual content that it is difficult to express as a painting. The bands of straight lines which make up the central polygon can be shown with bright colours interspersed with white. A broken image can then be painted in the centre. The break-up and distortion can be used with good effect to make it appear that the colours in the bands are shimmering. A fairly conventional, but somewhat misty and unfocussed watercolour painting outside of the central polygon completes the artwork. In this case it is possible to follow reality and show the larger area of disturbance as it develops.

The third type of visual migraine problem is different. It occurs again with spreadsheets, but for entirely different reasons. It also occurs with patterns in curtains, or domestic wallpaper, providing that there is repeating verticals pattern that is spaced at about the same distance as the distance between the eyes. It is triggered by relaxation and suddenly jumps into view. It produces a peculiar sense of space that is not really there. In a way it is even more disturbing than the visual problems with the central polygons. It can quickly lead to a sense of unreality and unballance. The effect can also be brought into play consciously, thus making it very easy to get a 3-D image from a stereoscopic pair of pictures that other people struggle to see.

This 3-D effect of a flat object is hard to represent in artwork. It can be demonstrated to some extent with computer generated wire-frame models. It two superimposed images of the same wire-frame mock-up have been computed from slightly different viewing positions, the effects begins to be seen.

An acquaintance who is a neuro-pathologist was able to tell me exactly which part of the brain caused the effects. They do not worry me too much. They first started some years ago immediately after using large quantities of insecticide. For two consecutive years in Northern Ireland there was a plague of Tiger Moth caterpillars which were stripping the thorn hedges of their leaves, and threatening to kill them. The hedges were draped in their silky nests. For two years I waged war with insecticides on the invaders of my hedges. Assuming that was the initial cause, it will be interesting to try to depict bare-twigged hedges with festoons of caterpillar nests with a centre of nothingness.

The resulting paintings are generally popular with the visitors when shown at art exhibitions.

© High Speed Ventures 2011