Tuesday, June 27, 2017

Answer: Seeing things?

We see things all the time...  

.. you often just don't notice.  This is part of the complexity of this Challenge--you see these visual effects often, but we almost never talk about them.  If that's true, HOW do you search for them?  

Here's what I did to find these answers.  

1.  When I went for a run a while ago, I scampered around a blind corner and smashed my forehead into a stop sign.  The impact didn't hurt much, but it dropped me flat on my back onto the sidewalk.  I got up quickly and resumed running.  Nothing was hurt, BUT this is what my visual field looked like: 

There was a relatively large C-shaped fuzzy spot just to the left of my visual center.  I fell on my back, so my eyes were untouched by the accident.  The good news is that this fuzziness went away on its own after about 1 hour.  Challenge:  WHAT is this visual disruption called?  Should I worry about it? 

As Remmij pointed out, this IS in Cupertino (when I worked for Apple), but not actually at this corner.  (I used this photo because it was really close to where the "stoppage" actually happened. But the real place is pretty unphotogenic.)  

I searched for: 

     [ C-shaped blur vision ] 

and found the Wikipedia article about scintillating scotomas, which are shimmering regions of the visual field that are often C-shaped and associated with migraines.  Here are two images from the Wikipedia article that illustrate this.  

These both are C-shaped in the same way as my blurred vision, and my visual effect did scintillate a bit, but this clearly wasn't a migraine.  Could a fairly simple head trauma cause this?  

As I read the article, I found a link to scotoma without the "scintillating" and found that this effect is sometimes caused by preeclampsia (a disorder sometimes found during pregnancy, not my problem), poisoning, demyelinating diseases, or migraines.  

Since this was a one time event, I wondered if my scotoma could be caused by hitting my head.  It's quite possible that I hit the back of my head on the sidewalk when I was abused by the stop sign. 

My next query was for: 

     [ scotoma head trauma ] 

I used the medical terminology "trauma" rather than "hitting my head" in order to get more medical results in my SERP.  

The second result led me to the page "Visual fields in brain injury" I learned something even more specific: that scotomas that look exactly like mine are also called Unilateral Temporal Crescent Scotoma or Half Moon Syndrome.  The page indicated that this can be caused by head trauma, so I modified my search to include this new descriptive term: 

     [ unilateral temporal crescent scotoma head trauma ] 

and found a few more pages (such as this one) that describe the visual effects after "traumatic brain injury" (TBI).  Clearly, I just had a whack on the head, and not really a serious brain injury.  But this IS one of the ways that your visual system can be disrupted.  

Bottom line: I had a scotoma after whacking my head pretty hard on the concrete.  Luckily, it resolved itself pretty quickly, so I never developed any of the more outrageous forms of the effect.  

2.  Unrelated to Challenge #1, I noticed recently that whenever I look up into a clear blue sky (or at a blank white wall) I see lots of small circles and a few "threads" kind of wandering around.  They're not big enough to obscure anything, and I don't notice them during the ordinary course of the date... but they're kind of odd.  Again, WHAT are these things called?  Should I worry about them?  
For this one, I did the query: 

     [ circles threads in vision ] 

which gave me a BUNCH of results about "floaters."  I mean, everything was about "floaters."  What are they?  Clicking on a few links (here's a good one from Eye Health Web) taught me that they are also known as vitreous floaters or eye spots, are tiny specks, circles, or thread-like clouds that appear in your field of vision. They are a common occurrence, and they can appear periodically or they can be around for quite a while.  

Eye floaters usually vary in size and shape. Although they can appear in youth, most people who experience eye floaters are over the age of 50 (that would be me).   Eye floaters can usually be seen when looking at plain, light-colored backgrounds (such as a wall or the sky) and may appear black, gray, white, or “see through.”

So, nothing to worry about, they're just a side-effect of having aging eyes.  Nothing to worry about.  

3.  Unrelated to #1 or #2:  Even though I have lots of experience seeing the world, I also noticed that when I close my eyes for a second and then look downward rapidly without opening my eyes, I see a fairly large circle appear and then disappear in a couple of seconds.  I'm surprised I've never noticed this before, but I have no idea what this visual effect is called or what causes it!  Can you tell me?  (And let us know if you see this circle appearing when you look down with closed eyes.)  

For this visual effect, my search was: 

     [ ring of light when I close my eyes ] 

which led me to a slightly gossipy site (Huffington Post) with a somewhat glib article about "rings of light"... but also had another word:  phosphene.  Since I didn't know that word, I did a: 

     [ define phosphene ] 

which told me that it was a "a ring or spot of light produced by pressure on the eyeball or direct stimulation of the visual system other than by light."  

Interesting.  So I changed my search to: 

    [ ring phosphene when I close my eyes ] 

which led me to Optometry Forum, which has an article on exactly this phenomenon.  That article suggested I do a search for: 

     [ phosphene entoptic phenomena ] 

which in turn led me to the Wikipedia page on Entoptic Phenomena (there IS such a page?).  There I learned more about floaters (confirming what I learned above), and more mentions of phosphenes as the probable cause of the rings I see when closing my eyes and looking down. 

--- Update to this page (June 28, 2017) -- 
As Regular Reader Judith pointed out:  

"Floaters that appear gradually and are there all the time are nothing to worry about.  However, if there is a sudden increase of floaters, it may be a medical emergency as this can be the sign of a retinal detachment.
Anyone who experiences an onrush of floaters should see an ophthalmologist immediately."  

She's right.  If you normally do NOT see floaters, but all of a sudden see a bunch of new floaters, get yourself to a doctor.  

 Search Lessons 

A couple of lessons here.... 

1. Sometimes you must go deeper.  In Challenges 1 and 3, we had to do an initial search, then decide what to learn from our initial results (usually additional terminology) in order to do a better search that will get us to higher quality results.  Pay attention to the language used in the results you find.  Even if that particular result isn't of high quality, it might well give you a search term or two that you CAN use to improve your searches.  

2. Use medical terminology for medical queries (but be sure you know the right terms to use).  In the scotoma example, I used the term "head trauma" to improve the quality (and targeting) of my search.  As always, be positive those specialized terms mean what you think they mean.  (Use define and friends to verify that you really know those words.)  

Not to worry, my vision is fine.  (So far at least.)  Hope you enjoyed this small medical mystery! 

Search on! 


  1. post L… first it's floaters, then follicle dysphoria/displacement & then the train gathers momentum on the descent… that's all.
    news on Google news… readable refresh
    from a tweet
    things are cyclical, even on the train

  2. Actually, the white spots / black threads are 'Blue Field Entopic Phenomenon' - I searched for 'white spots with trails on blue background', and found this wikipedia page (https://en.wikipedia.org/wiki/Blue_field_entoptic_phenomenon).

    I'd been told about it when I asked my optician, but it was good to find out more detail.

    It's the white blood cells moving through the capillaries of the eye, with a trail of red blood cells backed up behind them. The brain is normally very good at filtering this sort of thing out, but on a blue background they become especially apparent.

  3. post L… first it's floaters, then follicle dysphoria/displacement & then the train gathers momentum on the descent… that's all.
    news on Google news… readable refresh
    from a tweet
    things are cyclical, even on the train

    diagram from your UpToDate link
    concrete and cranial material… not always simpatico…
    [concrete sidewalk skull contact] image SERP