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Visual Snow Syndrome

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globe anatomy
anatomy of the eye (click on image to enlarge)

What is visual snow?

Visual snow is the name for a visual symptom that looks like static on a television not tuned to a station.  It has also been likened to pixelation on a computer screen.  Many tiny flickering lights are usually seen in both eyes at the same time and encompasses the entire visual field.  In some instances, it is worse in bright illumination like a bright sunny day.      

What is the difference between primary and secondary visual snow syndrome?

Visual snow may be seen in patients without an underlying disease.  In these cases it appears to be caused by hyperexcitability of the visual cortex of the brain.  This is often called primary visual snow syndrome (VSS).  Primary VSS is a diagnosis of exclusion.  That is, other diagnoses must be excluded before the diagnosis of primary VSS is made.  Primary VSS is related to migraine; indeed, many people who report visual snow also have migraine visual symptoms with or without headache.  Other related symptoms include palinopsia (visual persistence of an image after the eyes are closed or look away), floaters and spots (entopsia), difficulty seeing in dim light (nyctalopia), difficulty seeing in bright light (hemeralopia), and flashes of light (photopsia).   Other associated symptoms include ringing in the ears (tinnitus) and dizziness that varies with head position (postural vertigo).     

Visual snow may be a symptom of an underlying disease (secondary visual snow syndrome).  In this situation, it is critical to identify the underlying cause and offer treatment where possible.  Secondary visual snow may originate from the retina or the brain.  A well-described retinal cause of visual snow is due to digoxin toxicity.  It usually occurs in elderly people who take digoxin for heart problems.  It indicates the need to stop taking digoxin or lower the dose.  Failure to reduce the dose may result in severe complications, including death.  Other rare causes of visual snow include eye disease, immune disease, infectious disease, psychiatric disease, prescription drugs, past use of hallucinogens, head trauma, brain tumor, seizure disorder, and brain degenerative disease.

What causes the primary visual snow syndrome?

The cause of primary VSS is not known.  It is felt to be due to an error in central processing in the back of the brain (occipital lobe).  Special brain scans show hypermetabolism in the lingual gyrus of the occipital lobe in the back of the brain.  

How is primary visual snow syndrome diagnosed?

The diagnosis is made on the basis of typical symptoms after testing has ruled out an underlying disease of the eye or brain.  MRI brain scan is often used to rule out tumor, multiple sclerosis, degeneration, and stroke.  EEG may be used to rule out seizure disorder.  A spinal tap may be needed to rule out idiopathic intracranial hypertension.  Pattern reversal VEP usually demonstrates loss of habituation of the occipital lobe in the brain (indicative of hyperexcitability). A neurologist usually arranges for testing as needed. An ophthalmologist may be helpful in ruling out eye disease.

What can be done about these symptoms?

It is difficult to treat primary VSS.  Medications such as lamotrigine and topirimate may be helpful in some patients.  Tinted glasses or clip-on lenses may also be helpful to minimize the symptoms of visual snow.  Placing a yellow or orange tinted cellophane sheet on top of reading material helps some. Riboflavin and magnesium supplements may be of benefit for migraine and visual snow, as well. For many patients it is helpful to know that primary VSS is a benign condition that does not progress to blindness.

By Scott E. Pautler, MD

For a telemedicine consultation with Dr Pautler, please send email request to spautler@rvaf.com. We accept Medicare and most insurances in Florida. Please include contact information (including phone number) in the email. We are unable to provide consultation for those living outside the state of Florida with the exception of limited one-time consultations with residents of the following states: Alabama, Arkansas, Connecticut, Georgia, Minnesota, and Washington.

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Copyright 2022-2023 Designs Unlimited of Florida. All Rights Reserved.

Treatment of Floaters

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What are floaters?

Floaters are small specks, fibers, or bug-shaped objects that may appear to move in front of your eye.  At times they may appear like a veil or cloud moving in the vision.  Floaters differ from blind spots in the vision in that floaters have some degree of independent movement.  Blind spots are missing areas in the vision that move precisely with eye movement.  Although floaters do follow the movement of the eye, there is usually some degree of continued movement after the eye stops moving.  They are frequently seen when looking at a blank wall or blue sky. Floaters are actually tiny clumps of fiber or cellular debris within the jelly-like fluid (vitreous) that fills the inside of the eye.

What does this symptom mean?

Although many people have occasional floaters, the sudden onset of many new floaters with or without flashes is an important sign of abnormal pulling on the retina by the vitreous.  Sometimes, the retina tears and may cause loss of vision from detachment of the retina. At other times, floaters may persist and chronically interfere with vision.

What causes floaters?

Floaters are usually due to degeneration of the vitreous gel in the eye from aging.  Over time, the vitreous shrinks, condenses, and pulls away from the retina.  The condensation causes fibers and cellular clumps to pull away from the retina and float freely inside the eye. The shadow of these opacities is what we see as floaters. Other causes of floaters include trauma, bleeding, retinal breaks and detachment, eye surgery, inflammation, and cancer (very rarely). 

vitreous floaters and haze
Vitreous floaters and haze interfering with vision after repair of retinal detachment. The vitreous opacities appear as fibers and haze in this photo. They interfere with a clear view of the retina when looking into the eye and they interfere with the vision when looking out through the haze.

What can be done about floaters?

It is important to have a thorough dilated eye examination to determine the cause of floaters.  Treatment is dictated by the cause of the floaters.  If there is no serious underlying cause (retinal break, retinal detachment, etc.), no treatment may be needed. New floaters often fade without treatment.  It can be helpful to avoid tracking or following floaters to allow your brain to ignore them. Floaters are less obvious in a darker environment, so wearing sunglasses outdoors may help minimize symptoms of floaters. Stress and depression appear to aggravate the symptoms of floaters and may be treated separately. 

YAG Laser Treatment:  A special laser may be useful in some cases of persistent floaters. It is an office treatment in which the laser in used to break the floating fibers and clumps into smaller fragments in the vitreous of the eye.  Although it may help, YAG laser does not eliminate floaters.  Repeat treatments are frequently necessary. Complications may include bleeding, increased floaters, retinal breaks and retinal detachment, which may require surgery to prevent blindness.  There is limited evidence on the safety and effectiveness of YAG laser for floaters and it may not be covered by insurance. YAG laser may result in loss of vision/loss of the eye.

Vitrectomy Surgery: Vitrectomy is a surgery performed in the operating room. It is commonly used to treat serious problems of the vitreous and retina.  It is very effective at reducing or eliminating floaters.  However, complications include bleeding, infection, retinal break and retinal detachment, which may require surgery to prevent blindness.  Serious complications occur in 1-2% of eyes reported in most studies, although some reports suggest the risk of complications may be as high as 10%.  The most common problem with vitrectomy is cataract formation.  After vitrectomy, cataract may develop over months to years and often requires cataract surgery.  Glaucoma has been reported years after vitrectomy, but the exact incidence is not known.  Vitrectomy surgery may result in loss of vision/loss of the eye.

For most patients the best course of action is observation of floaters without treatment at first.  If symptoms persist and significantly interfere with vision despite 6-12 months of observation, treatment may be helpful.  Most patients report good results with vitrectomy, but the possibility of complications must be carefully considered and accepted prior to embarking on surgery.

By Scott E. Pautler, MD

For a telemedicine consultation with Dr Pautler, please send email request to spautler@rvaf.com. We accept Medicare and most insurances in Florida. Please include contact information (including phone number) in the email. We are unable to provide consultation for those living outside the state of Florida with the exception of limited one-time consultations with residents of the following states: Alabama, Arkansas, Connecticut, Georgia, Minnesota, and Washington.

Copyright 2019-2022 Designs Unlimited of Florida. All Rights Reserved.