My 5 year old cat has had a bad ulcer on his rt. cornea for the past year.
We've been going to the vet opthamologist here in Dallas on a monthly basis.
He's been treating Dusty for bacterial, viral (herpes) and other infections
using bactrimycin, polymycin, teramycin and other mycins!  The ulcer has
almost gone away twice but has relapsed both times we thought he was over
it.  The vet also treat w/ idoxuridine, an eyedrop that was mixed at our
local pharmacy.  Well, it seems when we retreated w/ the idox, the ulcer
came back really bad and the vet has been puzzled.  He sent some little
white specs off to the lab but they couldn't get them to grow into any
recognizable culture.  So now the vet thinks maybe the idox was not mixed
correctly.  The idoxuridine is used for the herpes virus and now the vet
thinks he actually has herpes which he ruled out several months ago since he
thought the idox should've cured it.  So now we're using a drop containing
neomycin w/ polymycin B  AND dexamethasone (corticosteroid) and it seems to
be stopping any further growth of the ulcer.  It has also stopped the gookie
junk that is a byproduct of the ulceration and scar tissue formation.  The
next step will be to use another anti-viral herpes medication since he now
thinks it really is the herpes virus.  This cat has had 2 other ulcerations,
always in the rt. eye, and had responded to the teramycin treatment a few
years ago, but not in the past year. So I guess the vet thinks it definitely
is the herpes virus and we'll start the next drug this week.
So to make a short story long, this is what you may be up against w/ your
kitty.  Definitely get him to a vet who can treat eyes properly.  If the
ulceration gets really bad, it can destroy the cornea enough to cause the
cat to lose his eye.  We've spent >$1000 on this and basically it's been
hit-and-miss.  The vet said if he were to do a scraping and send it off to a
lab, it would be more expensive than to treat for every possible cause.

Good luck,
Chris and "Dusty"

Sounds like a cataract.

It could possibly be a cataract, though certainly ask the vet about it.
One of my cats developed a similar spot around the age of three, and we
went directly to an animal eye specialist (knowing it wasn't an
infection or anything). It's a cataract that's causing pressure in his
eye, and he gets predniszone drops 3x per week, and checkups every 6
months. It's really easy to take care of, and he takes the drops well.
He doesn't have sight in that eye, but has adapted great in every way.
Rene