Tag Archives: cause

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.

Black Spots After Eye Injection

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

What are these circular spots in my vision after an eye injection?

Sometimes after an eye injection, a patient may see one or more black circular spots that move in the vision with head movement.  They are usually in the lower part of the visual field, though they move up toward the center of the visual field if you position your head face down.

What causes these symptoms?

These black spots are due to air bubbles in the medicine that is injected into the eye.  They appear immediately after injection.  They are harmless and take 1-2 days to dissolve and disappear.  Less commonly, small black circular spots may float in the vision after injection due to small silicone bubbles that are used to lubricate the syringe.  These silicone bubbles do not dissolve, but they may float away from the retina and become less noticeable over time.

What should be done about these symptoms?

If the spots are due to air bubbles, these symptoms fade without treatment.  If the spots are due to silicone bubbles, they may come and go over time.  It is best not to track them with your eyes as they may become more bothersome.  Try to look past these floaters and ignore them if possible.  If they persistently interfere with the vision, vitrectomy surgery may be considered to remove them.  This is rarely necessary.

What other symptoms can mimic this problem?

These black spots are considered a type of “floater.”  Floaters are any visual spot in the vision that “floats” or moves somewhat independent of eye movement.  Sometimes floaters may come on suddenly and appear like dots and fibers.  This is typical for bleeding inside the eye.  If dots and fiber-like floaters come on more slowly (hours to days), they may be a sign of infection or inflammation.  Rarely, cancer may present as many tiny floating spots in the vision.   

Floaters are distinct from blind spots (scotoma) that are fixed in the visual field and move only when the eye moves.  You cannot “catch up” or move away from a blind spot by moving the eye.  Blind spots are usually due to problems with the retina or optic nerve.  A progressive blind spot that begins in the peripheral vision and enlarges over hours to days may be due to a retinal detachment and requires a prompt examination.  Retinal detachment is often described as a curtain or shadow covering the vision.

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 2022 Designs Unlimited of Florida. All Rights Reserved

Uveitis Questionnaire

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Below is a downloadable form to fill out and bring to your doctor. This questionnaire may help identify the underlying cause and help with treatment of uveitis.  

By Scott E. Pautler, MD

For a telemedicine consultation with Dr Pautler, please send email request to RvaAdmin@rvaf.com. We accept Medicare, most insurances, and self-pay.

Uveitis-Questionnaire-v20220204Download

Posterior Uveal Effusion

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

What is posterior uveal effusion syndrome (PUES)?

PUES is an abnormal leakage of clear fluid under the retina, which causes symptoms of blurred vision, sometimes with distortion of straight lines. It is also call the peripapillary pachychoroid syndrome. This condition frequently presents as central serous retinopathy. The retina is a thin layer of delicate tissue in the back of your eye, which lines the inside wall like the film in a camera. The retina “takes the picture” of objects you look at and sends the message to the brain.

What causes PUES?

PUES appears to be due to an abnormal leakage of serum (clear fluid) from blood vessels in the choroid. The choroid is a layer of tissue with many blood vessels lying under the retina. When the choroid is thick, it may abnormally leak fluid into the retina (Figure A-D) causing visual symptoms. Thick choroid is seen more commonly in far-sighted eyes than near-sighted eyes.

PUES
Thickened choroid leads to leakage of fluid into the retina

What is the treatment of PUES?

If the leakage is mild, observation may be all that is needed. If symptoms of blurred vision become significant, treatment may include eye drops or pills taken by mouth (Figure E-F). In rare cases, laser treatment or surgery in the operating room may be required to control the leakage. An attempt is made to eliminate aggravating factors such as ocular inflammation and, rarely, medications.

What will happen to my vision?

With prompt treatment the vision usually remains stable. In some cases, there may be a degree of permanent damage to the retina affecting the vision from past leakage that cannot heal. Treatment needs to be continued as a return of leakage may occur is medications is stopped (Figure G-H).

For more information see: Isolated Posterior Uveal Effusion: expanding the spectrum of the uveal effusion syndrome.

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 © 2015-2022 Designs Unlimited of Florida. All Rights Reserved.