Optic neuritis

Carol LeBlanc, Example of how optic neuritis affected one eye of a patient with multiple sclerosis, 2008 (quoted from Wikipedia article Optic neuritis; larger image see here)

Optic neuritis, also called retrobulbar neuritis, is the inflammation of the optic nerve that may cause a complete or partial loss of vision (Brass et al., 2008) and sometimes present with visual snow, as shown in the above illustration. As optic neuritis commonly affects one rather than both optic nerves, visual snow due to optic neuritis is most often a monocular visual disturbance, in contrast to the visual snow in the entire visual fields of both eyes that occurs in persistent aura without infarction or HPPD. The most common etiology of optic neuritis is multiple sclerosis (MS), which can be diagnosed on the grounds of pathological findings in neurological examination, MRI, lumbar puncture, visual evoked potentials (VEPs) and/or somatosensory evoked potentials (SEPs), whereas persistent aura without infarction or HPPD display normal findings in the aforementioned medical tests.

IanKC (subject #92), administrator of the Yuku (formerly Ezboard) forum Visual snow or static since 2004, related: "I don't recall any poster here ever being diagnosed with either MS or optic neuritis" (see here). However, according to viper123456's (subject's #42) experience, "MS is often the first diagnosis neurologists pursue with VS patients", as both persistent aura and MS are neurological disorders that may present with multifocal symptoms. In the further diagnostic work-up, however, MS can be ruled out by normal results in cerebral MRI, lumbar puncture and evoked potentials. When Neurogurl (subject #277) called her doctor for the random form visual hallucinations (sparkles, flashes, floaters) and vestibular symptoms brought on by her 1st and 2nd episode of persistent aura, "She said, hmm... sounds like MS with the vision", but this suspected diagnosis could subsequently be dismissed on the grounds of her normal MRI and other neurological findings. Similarly, SopuliSusie (subject #405) confirmed: "It would also be more rare to have identical symptoms in both eyes from optic neuritis. But yeah, it was the first thing they checked for me (didn't have it)."

jruddy, Visual snow, 2008. © 2008 jruddy (larger image see here)

However, a diagnosis of optic neuritis was reported by 2 respondents to the Sofia Greene survey on persistent perception disorders. One "vs lifer" (subject #320) with bilateral visual snow in his whole visual fields sustained a unilateral optic neuritis occurring ca. 29 years after the onset of definite persistent aura without infarction, a chronology that excludes the optic neuritis as cause of his persistent visual snow. A second subject (#514) got bilateral visual snow as symptom of bilateral optic neuritis caused by MS. "Anyway, what I do know... from my own experience", he wrote, "is that optic neuritis is capable of causing persistent visual snow of similar, though maybe not entirely identical, appearance on both eyes, with no loss of vision on either eye... I wasn't able to produce anything that actually came close to what I see. Fortunately, the following image by jruddy (see above) shows visual snow that is similar to mine." In February 2004, the then 22-year-old American Caucasian male developed visual snow mainly in the peripheral visual fields of both eyes, followed by visual snow also in the central visual fields since April 2005. Repeated eye examinations and VEPs were all normal. "I didn't learn the cause of my VS until three years after the onset when they finally gave me an MRI." In May 2007, the intensity of visual snow worsened especially on the right eye, and one month later there was a gradual decrease, over a period of about two weeks, of the visual acuity of the right (20/40) and left eye (20/25). Except for occasional feeling of pins and needles or numbness and frequent tiredness the neurological history was unremarkable. A diagnosis of bilateral optic neuritis caused by MS was made on the grounds of the above clinical presentation and pathological results of VEPs (reduced on the right side, normal on the left side), spinal tap (oligoclonal bands), T2-weighted cerebral MRI (several lesions, some of them active) and spinal MRI (a couple inactive lesions) without and with gadolinium. Therapy with high dose methylprednisolone (1000 mg for 3 days) resulted in subsequent improvement of visual snow and visual acuity (20/30 right eye, 20/20 left eye). From August 2007 on, a therapy with interferone (Avonex 30 µg one injection per week) was given; no new episodes of MS have occurred ever since.

References

Brass SD, Zivadinov R, Bakshi R. Acute demyelinating optic neuritis: a review. Front Biosci 2008; 13: 2376-2390.

We wish to thank timmcc (subject #514) for the reference to Carol LeBlanc's image from the Wikipedia article Optic neuritis (Yuku forum Visual snow or static - General discussion - Optic neuritis is one cause of visual snow, January 17, 2008)

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