I have the visual photosensitivity thing (have complex partials).  Maybe if I
tell you what I've noticed over the years, it will help you.  Anything that is
moving whether you can obviously see it or not (like computer monitors or
fluorescent tubes).  TV isn't real bad for me although if the station has a
rolling text area at the bottom of the screen (like during the news), that is
annoying.  I've even had to cut my bangs because if they get in my line of
vision, it can cause problems.  If I'm not feeling real good, I can't read
because even my own eye movements back and forth make me feel worse.  Patterns
such as floor tiles, floral draperies, patterned upholstery are not
comfortable.  Intense color contrasts is another annoyance.  Anything that is
very shiny like polished metal and highly polished floors (if I'm sitting still
they're okay, but if I'm walking it can be a problem).  I haven't had this
problem myself (yet) but flickering shadows created by trees and telephone poles
can cause problems for some people.

I've never had instantaneous effect from a photosensitivity trigger with the
exception of walking in a mall that had highly polished floors (but this mall
also had a lot of everything else that bothered me).  In this case, the solution
was to avoid looking towards the floor when I walked.  I have tried sunglasses
to reduce contrast.  I've tried wearing a baseball cap especially while driving
(to eliminate shadow flicker from trees, telephone poles).  I've removed my
glasses to try to blur patterns, color contrasts, etc.  Our house is decorated
in neutral colors with limited patterns.  I want to go back to the baseball cap
for a second because I've noticed that it helps prevent flickers directly
hitting the eyeballs in some situations, but I've noticed that movement outside
the edge of the brim seems to be more pronounced and can be kind of annoying.

If I am outside walking around our yard, for example, I don't have as much of a
problem with some of the things that bother me indoors.  For example, I can
tolerate wind blowing tree branches or plants and grasses very nicely.  I can't
recall ever having a seizure while using a riding lawn mower although I've had
seizures while driving (years ago before I was diagnosed).

I mentioned the mall a couple of paragraphs ago.  We had two malls at that time
Oakwood and London Square.  London Square was very bland, gray tiled walls and
floors, no metal decorations, no blinking lights, etc. while the Oakwood mall
had highly polished tile floors, shiny metal support posts, open store fronts so
you could see a real mishmash of colors.  The Oakwood mall was a problem because
of all the triggers.  I never had problems in the bland London Square mall even
though the walls and floors were tiled.  My kids noticed that I had to go sit
down and rest every time we visited the Oakwood mall.  I never would have
noticed this myself.

Since I've been medications, the photosensitivity thing is much less evident,
but if I get sick (which can provoke seizures in me), I definitely have to go
back to avoiding the same visual triggers.  I mean, I try to avoid those
triggers all the time, but sometimes you can't avoid them.  It helps a little
bit if I can get into a very bland environment, which is almost impossible to do
or find.  At times, I've noticed that even closing the eyes doesn't help me
because I can "see" little dull sparkly things.

The last thing I want to say is I think photosensitivity triggers are all around
us (my impression is some of them might be low level and  cumulative) and I
think some triggers, like a bad computer monitor, just push our brains over the
edge so to speak.  I don't know if there is a difference in the potency of
different visual triggers, but I'd sure suspect a couple of things (like a bad
computer monitor, blinking lights, etc.) as being faster to provoke a seizure
than other things.

Barb