What is this Phone/Eye Icon in my notification bar?

This icon appears seemingly at random, especially on my lock screen but not always. I can almost guarantee it pops up if I make a screenshot but I am not sure. I am on an LG Volt phone from Boost Mobile, and I was able to (finally) screenshot this icon after wondering about it for over a month.

A screenshot of the image is here: http://ift.tt/1y79HQw

Any guesses or preferably solid answers to what this could be are very much appreciated! It only appears for a brief moment (sometimes not even a second) before it disappears again.

I want to reiterate I see it most on my lock screen, but there could be other times it happens that I am not noticing.

Thank you in advance for your assistance in identifying what this is!