Patients with visual snow syndrome should be evaluated and treated

(Image credit: AdobeStock/Andrew Mayovskyy)

Reviewed by Elena Papageorgiou, MD

Elena Papageorgiou, MD, believes that patients who present with the complaint of visual snow should be counseled and be examined to rule out causes other than idiopathic visual snow syndrome (VSS). She presented the “YES” side of the debate on the topic at the 15th annual Controversies in Ophthalmology Congress in Athens. She is from the Pediatric Ophthalmology, Strabismus and Neuro-Ophthalmology Department of the University Hospital of Larissa, Greece.

VSS defined

The International Headache Society provided the following criteria for visual snow syndrome (VSS):

• VSS is defined as the presence of dynamic, continuous, tiny dots in the entire visual field for longer than 3 months.

• The presence of at least 2 of the following to satisfy the definition: palinopsia, photophobia, nyctalopia, and positive visual phenomena, such as floaters and photopsias.

• No migraine visual aura

• Symptoms are not explained by another disorder as ruled out by normal ophthalmic tests and no intake of psychotropic drugs.

Previous studies have attempted to determine the etiology of VSS. Yoo et al. reported that 20% of suspected VSS cases had other causes, including cone-rod dystrophy¹; other studies suggested birdshot chorioretinopathy,² autoimmune retinopathy,³ and glycine receptor autoimmunity⁴ as possible causes of the VSS; additionally, 11% of patients with early retinitis pigmentosa (RP) had no clinically visible pigmentary changes and may present with visual snow.⁵

Differential diagnosis

The ophthalmologic workup includes exclusion of RP, age-related macular degeneration, cancer-associated retinopathy/melanoma-associated retinopathy, cone-rod dystrophy, multifocal choroiditis, central serous retinopathy, optic atrophy, birdshot chorioretinopathy, and optic neuropathies.

Clinicians should do a thorough history-taking, routine ophthalmologic examination, color vision and visual field tests, optical coherence tomography, fundus autofluorescence, and electroretinography.

The potential neurologic causes include any visual cortex abnormality, such as occipital strokes, multiple sclerosis, neoplasm, neurodegenerative diseases/posterior cortical atrophy, idiopathic intracranial hypertension, and Creutzfeldt–Jakob disease; use of hallucinogenic drugs; any degree of traumatic brain injury, occipital lobe epilepsy, and migraine. The neurologic workup includes a neurologic consult, magnetic resonance imaging (MRI) and electroencephalography; functional MRI and positron emission tomography also may be considered in selected cases.

Papageorgiou explained that migraine treatments generally do not improve VSS, and VSS is often misdiagnosed as persistent migraine aura.

There are clear difference between migraine with visual aura and VSS. The former is temporary, occurs before or during a migraine episode, and moves slowly across the visual field; in contrast, VSS is more consistent, can occur independent of migraine, and is static in the entire visual field.

Elena Papageorgiou, MD
(Image courtesy of Elena Papageorgiou, MD)

Treatment

There is no widely accepted standard treatment for VSS. Papageorgiou advises counseling patients on the benign and relatively stable nature of VSS. Patients are advised to avoid using recreational drugs and alcohol.

One study6 reported that in 153 patients, 8 of 44 medications evaluated were effective. Lamotrigine and topiramate were the most efficacious; other included acetazolamide, propranolol, verapamil, and antidepressants.

Other approaches that might be beneficial include management of comorbidities such as migraine, depression, and tinnitus; using color filters of the yellow-blue color spectrum resulted in about 90% improvement of the visual static; repetitive transcranial magnetic stimulation; and mindfulness-based cognitive therapy such as coping skills and distractions.

Caveats

Physicians and patients should know that not all VSS cases are benign. Factors to watch for are new-onset VSS especially in older patients, intermittent VS or sudden exacerbations, the development of unilateral or quadrant VS, accompanying ocular/neurologic deficits, and VS mimics, such as neurologic disorders, ocular pathologies, drug-related VS, and systemic diseases.

References

1. Yoo YJ, Yang HK, Choi JY, et al. Neuro-ophthalmologic findings in visual snow syndrome. J Clin Neurol. 2020;16:646-652. doi: 10.3988/jcn.2020.16.4.646.

2. Patel RC, Vitale AT, Creel DJ, Digre KB. Not all that flickers is snow. J Neuroophthalmol. 2021;41:e97-e99. doi: 10.1097/WNO.0000000000000935.

3. Fraser CE, Vaphiades MS, Van Stavern GP, Lee AG. Should visual snow and visual snow syndrome be evaluated outside of standard in-clinic ophthalmologic testing? J Neuroophthalmol. 2022;42:384-389. doi: 10.1097/WNO.0000000000001675. Epub 2022 Aug 2.

4. Piquet AL, Khan M, Warner JEA, et al. Novel clinical features of glycine receptor antibody syndrome: A series of 17 cases. Neurol Neuroimmunol Neuroinflamm. 2019;6:e592. doi: 10.1212/NXI.0000000000000592.

5. Lee EK, Lee SY, Ma DJ, et al. Retinitis pigmentosa sine pigmento: clinical spectrum and pigment development. Retina. 2022;42:807-815. doi: 10.1097/IAE.0000000000003367.

6. Eren O, Schankin CJ. Insights into pathophysiology and treatment of visual snow syndrome: A systematic review. Prog Brain Res. 2020;255:311-326. doi: 10.1016/bs.pbr.2020.05.020. Epub 2020 Jun 15.