You should ask your family doctor for the name of a good
ophthalmologist.  (Your optician should have suggested same!).  And you
should do that right away.   Good luck.

Don W

You need to do a better job of quantifying this dark spot.  Try this:

Make a tiny mark on a wall and back up to where you can just see that mark.

Looking at the mark, is the dark spot above, below, to the right of,
right on the  mark or what?

How large is the spot relative to the mark?

Is it in the right, left or both eyes?

Is it always the same (location, size, laterality)?

If you look at a spot just below the mark, does the dark spot move down
about the same amount, or does it stay in its original position?

Does the dark spot obliterate whatever it's "on", or is it more
transluscent, can you see through it more or less?

w.stacy, o.d.

Yes, sounds like the symptoms I have had on and off for almost 4 years
now.  If you are looking at a bright light source you will get an after
image for a short period of time (a few seconds).  If you kind of
squint your eye and there is a translucent/opaque or "after image"
looking area it could be a symptom of an underlying problem with the
retina and should be looked at by a retina specialist.  A normal
opthomologist may or may not be equipped to handle this type of
problem.  What most likely will happen is you will need a flourascein
(sic) angiogram of both eyes.  In my case I have a condition called
"Central Serous Choroidopothy" which is a leak in the vascular layer
directly behind the retina resulting in a bulge in the retina causing
the visual disturbance.  The cause for this is not known but it is
widely thought it is stress related.  When I first noticed it in my
left eye I was walking outside in daytime and I just happened to look
at a white surfaced and noticed that I had an "after image" visual
disturbance when I sort of squinted.  It was only in my left eye, not
my right.  Fortunately my brother inlaw is an opthomologist and after
examining my eyes and doing several tests he told me he thought it
might be CSC and that it should resolve on its own after a few months.
It did but it returned later on.  That second attack also resolved but
recently it's flared up again.  This last time I finally saw a retina
specialist who confirmed the diagnosis.  Now I have a very distinct but
small visual disturbance in my left eye and slight visual impairment
(correctable with glasses).  My advice - get it checked out !! if the
leakage does not resolve there is laser surgery treatment that can be
performed. Luckily for me I haven't come to that and hopefully will
never have to.

good luck !