Fibromyalgia, the Optic Nerve, and Neurodegeneration

Abnormalities Discovered in the Eye

A close-up of a man's eye reflecting a circle of lights in his pupil.
Researchers are looking in the eye for clues to fibromyalgia. Milan Tarlac / EyeEm / Getty Images

Are the eyes the window to whatever's going wrong with the brain in fibromyalgia? Research published in 2015 and 2016 suggests that it just might be.

Fibromyalgia is widely believed to be a condition of the central nervous system, which includes the brain and spinal column. It also includes the eyes and the structures that help our brains interpret what we see.

Chief among these structures is the optic nerve, which is similar to a cable made up of many smaller fibers.

Among them is a layer of nerves called the retina nerve fiber layer (RNFL).

Those nerve fibers are of special interest to researchers because of other recent work that's uncovered dysfunction of the small nerve fibers. It suggests that, in people with fibromyalgia, small-fiber neuropathy (nerve damage) may be responsible for at least some of the pain.

In two studies, Spanish researchers have also discovered evidence of neuropathy in the small fibers of the eye.

Blood-Flow Problems

In the study published in 2015, researchers looked at blood flow to the optic nerve and the RNFL. Blood flow, also called perfusion, is hypothesized to be irregular in several regions of the brains of people with fibromyalgia.

Researchers examined and took photographs of the eyes of 118 people with this condition plus 76 healthy people in the control group.

The photos were then analyzed with special software. The researchers concluded that the fibromyalgia eyes did in fact show low perfusion rates in several sectors, but the only significant difference was in certain RNFL.

Optic Nerve Thinning

The study published in 2016 built on that research, involving many of the same researchers. This time, they included 116 people with fibromyalgia and 144 in the control group.

They found:

  • a significant decrease in the RNFL in fibromyalgia compared to controls
  • a thinning of multiple structures in the eye
  • greater optic nerve thinning in those with severe fibromyalgia than in those with a milder case
  • greater optic nerve thinning in subgroups without depression than in those with depression

Neurodegeneration

Before now, fibromyalgia has been considered non-neurodegenerative, meaning that no biological structures were being damaged or destroyed as they're known to be in other neurological diseases such as multiple sclerosis or Alzheimer's disease.

However, this research suggests that fibromyalgia may in fact involve some neurodegeneration in structures inside the central nervous system.

This, combined with earlier research on small nerve fiber damage in the skin, could mean that the degeneration is not confined to the central nervous system but may extend to the peripheral nervous system, which includes the nerves in the limbs, hands, and feet.

What Does it Mean?

Fibromyalgia has always posed problems for doctors. We have pain, but no obvious cause. If this research is accurate, which we won't know until it's been replicated, it could mean that our pain comes from a very understandable source.

After all, neuropathic pain has been recognized for a long time. Suddenly, it makes our "mysterious" pain not mysterious at all.

On the other hand, it opens new doors for questioning. If we have damaged nerves, then why? What is causing the damage?

Possible candidates could include autoimmunity, which would involve the immune system going haywire and attacking the nerves as if they were bacteria or viruses, or possibly problems with how the body uses substances that grow or maintain nerves.

Researchers have long speculated about possible autoimmunity in fibromyalgia, but so far we don't have solid evidence pointing toward it. Now that researchers have discovered actual damage, they may gain better insight into where to look for autoimmune activity. They may also be able to pinpoint shortages or inefficiencies in how nerves are maintained.

When it comes to diagnostic tests, it's too early to say whether abnormalities in the eye could lead to a more objective test than we currently have. If so, it would be a major advancement in how fibromyalgia is detected.

Because the thinning was worse in more severe cases, it could provide a marker for doctors to monitor treatments as well as progression.

It's also possible that these discoveries could lead to targeted treatments.

We won't know the full impact of this research for some time, as any advancement in diagnostics and treatments would have to come after further research either confirms or contradicts these findings.

Sources:

Garcia-Martine E, Garcia-Campayo J, Puebla-Guedea M, et al. Fibromyalgia is correlated with retinal nerve fiber layer thinning. PLoS One. 2016 Sep 1;11(9):e0161574.

Pilar Bambo M, Garcia-Martin E, Gutierrez-Ruiz F, et al. Study of perfusion changes in the optic disc of patients with fibromyalgia syndrome using new colorimetric analysis software. Journal francais d'opthalmologie. 2015 Sep;38(7):580-7.

Uceyler N, Zeller D, Kahn AK, et al. Small fibre pathology in patients with fibromyalgia syndrome. Brain: a journal of neurology. 2013 Jun;136(Pt 6):1857-67.

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