Restricted Spatial Windows of Visibility in ME (2018) Hutchinson et al.

[Daisymay]

http://www.mdpi.com/2411-5150/2/1/2

Restricted Spatial Windows of Visibility in Myalgic Encephalomyelitis (ME)

Nadia S. Ahmed, Irene Gottlob, Frank A. Proudlock and Claire V. Hutchinson *
Department of Neuroscience, Psychology and Behaviour, College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK
Received: 22 November 2017 / Accepted: 11 January 2018 / Published: 17 January 2018


Abstract
Myalgic encephalomyelitis (ME) is a devastating disorder marked by debilitating fatigue. It not well understood and its diagnosis is controversial. It is very important therefore that significant clinical features are investigated. Visual symptoms in ME represent a group of distinct, quantifiable, clinical features that could significantly improve diagnosis and provide insights into underlying pathology.

The purpose of the present study was therefore to explore the effect of ME on spatial windows of visibility using the spatial contrast sensitivity function. Contrast sensitivity was determined for stationary luminance-defined sinusoidal gratings spanning a five-octave range of spatial frequencies (0.5 to 16 c/deg) in a group of 19 individuals with ME and a group of 19 matched (age, gender) controls. Compared to controls, the ME group exhibited a restricted spatial window of visibility for encoding stimulus contrast. This was characterised principally by a contrast sensitivity deficit at lower spatial frequencies and a narrower bandwidth.

Our findings suggest that contrast sensitivity deficits may represent a visual marker of ME, and be indicative of abnormal visual processing at the level of the retina and in the cortical and subcortical visual pathways.

Full-Text - http://www.mdpi.com/2411-5150/2/1/2/htm

 

[Andy]

Thanks for posting Daisymay. I've just edited it to make the text the normal size and put a few line breaks in the abstract to make it easier to read.

 

[Andy]

This work was funded by Fight for Sight and The Thomas Pocklington Trust.

Interesting, not heard of them before. Both of them are concerned with sight loss, I wonder why the interest in sight issues in ME.

 

[Liv aka Mrs Sowester]

Visual disturbances were amongst my earliest symptoms. I assume they are connected to OI and lack of oxygen?

 

[lansbergen]

Interesting, not heard of them before. Both of them are concerned with sight loss, I wonder why the interest in sight issues in ME.

My eyesight is still bad.

Pupilreflex still does not work well and contrast kept going downhill.

The more I try to focus the worse it gets.

 

[Mithriel]

I can't see moving images as it is processing within the brain that is the problem, not fast enough for tracking. Double vision has plagued me since the start and I have had episodes of blindness (which may be MS) Bright lights also close down my vision for hours. It is time that more work was done on the vision problems we have. I can cope with the wheelchair, not being able to do things for myself, even the pain carries some possibility of relief but I am completely helpless when I am blind. I do not know how people cope.

 

[Skycloud]

A possible objectively measured marker?

I wonder why the interest in sight issues in ME.

The references to other research into sight issues was interesting to note as I wasn't aware of it before. I hope my optician knows this stuff.

Snippets I thought were interesting:

Changes in contrast sensitivity are well documented in ageing [17] and are evident in a range of retinal diseases [18]. They are also present in neurodegenerative diseases such as Parkinson’s disease [19] and in inflammatory autoimmune diseases such as multiple sclerosis [20,21,22]. Contrast sensitivity deficits can be present even when there is no detectable impairment in visual acuity.

All patients had a medical diagnosis of ME, confirmed with the DePaul Symptom Questionnaire [23]. Only participants who fulfilled these criteria were included.

People with ME report a range of visual issues. Many more are mentioned here than I was aware of.

Like people with ME, MS patients exhibit a wide range of visual symptoms.

Optic neuritis is common [31] along with reports of loss of vision, colour vision disturbances, pain in the eyes, blurred vision, and visual fatigue [30,31]. A number of studies have examined contrast sensitivity in MS, and although the spatial frequency specificity varies between studies, there is agreement that poor contrast sensitivity is associated with the condition [20,21,22]. MS and ME share phenomenology and neuroimmune characteristics [32]. The onset of ME has been associated with infections and autoimmune disorders and, like MS patients, people with ME exhibit a range of immune abnormalities indicating dysregulation of the immune system [33]. As such, contrast sensitivity deficits, as well as representing a possible clinical marker of ME, may also lend weight to the notion that ME, like MS, is a disorder of the autoimmune system.

One notable limitation of our study concerns our ME sample. Our visual testing protocols required carefully calibrated equipment. As such, we were only able to test ME patients who were able to travel to the university to take part in the study. Whilst the participants in our study were significantly affected by ME, we were unable to measure contrast sensitivity in those most severely affected, e.g., those who are bedbound by the condition. As a result, our findings are likely to underrepresent deficits in this group.

There was also a discussion of the limited utility of the method used in this study for clinical settings; and also of other the usefulness of other methods.


I thought this was really interesting.

 

[Snow Leopard]

I am interested in sight issues as well as I suffer from strong eye pain and eye sight degradation over the last 4 years or so.

The visual issues may be nonspecific and associated with fatigue in general, but it shows that our fatigue has physical effects and is not merely a mistaken signal to be ignored, nor is it merely a muscular problem due to deconditioning.

 

[Forbin]

Commonly-reported visual symptoms include photosensitivity, difficulty focussing on images, blurring of images, halos around images, poor depth perception, pain in the eyes, impaired visual attention, increased susceptibility to pattern glare, and vision-related headaches [7,8,9,10,11]. A number of visual problems have also been identified objectively using experimental measures and include, reduced visual accommodation and poor binocular vision [12,13], increased susceptibility to pattern-glare [14], inaccurate eye movements [15], and impaired visual attention, particularly on tasks on which performance relies upon the ability to detect and/or identify an object whilst ignoring irrelevant visual distractors (selective attention) [16]. Visual symptoms are a pervasive part of the condition, exacerbate other symptoms, and affect the ability to carry out every day tasks [7,8,9]. Indeed, some studies report that up to 25% of those suffering from ME reduce the frequency of driving or stop driving completely due to the vision-related problems they experience [7].
http://www.mdpi.com/2411-5150/2/1/2/htm

The reference to increased susceptibility to "pattern-glare" interested me because I'd had not seen that term used in connection with ME before.

When I went looking for examples of pattern glare, I found the image below, here.

The most unnatural image is one in which all the contrast energy is concentrated in one orientation, and at a limited range of phases and spatial frequencies, such as the scene in figure 2.

Figure 2: An aversive grating

The image that results approximates a grating and the grating is unpleasant to look at if it has a spatial frequency close to that at which the visual system is generally most sensitive – about three cycles/degree.2 Gratings with these spatial characteristics induce a strong neurological response within the visual system:

• they are readily seen at low contrast.3
• they interfere with vision, masking low contrast images.4
• they induce a visual evoked potential of relatively high amplitude.5
• they induce a large haemodynamic response,6 consistent with the inefficient neural processing suggested by computer models.7

Such gratings also give rise to perceptual distortions of colour, shape and movement.2 The cluster of symptoms of perceptual distortion and discomfort that periodic visual patterns evoke is sometimes called pattern glare. https://www.opticianonline.net/cet-archive/171

This kind of pattern, seen in the real world, would drive me up the wall when my symptoms were severe.

This is an interesting paper. The people who wrote it seem unusually well informed about ME.