Sick Koi, please help

I have a Koi that has developed something very strange and
(unfortunately) new to me.
I have noticed that for the last couple of days he was acting strange
sitting very close to the the edge of the pond between 2 marginal
plants and was not moving at all.
I had a close look and I couldnt see anything unusual ( then again lots
of Koi problems cannot possibly be noticed with a free eye).
For the next couple of days after that he acted and ate as normal until
today when I noticed him again in the same place.
I had another close look and I got very upset as the fish has developed
something over his eyes that it makes his eyes look like they are
glazed. (white glaze).
I stuck my finger inside the water next to him and he didnt make a move
which makes me believe that his eyes are very much affected. I just
hope that the problem didnt blind him nor that may do in future.
I just put him into a quarantine tank which i have for fish with
problems with a mature filter and lots of air. The problem is that I do
not know exactly what seems to be the problem so I just added to the
water a 0.3% salt and nothing else.
Has anyone any idea what is may be and what treatment I can use.
For the last couple of days has been very hot in British terms and my
pond has shown an increase in ammonia and nitrite levels.
I have alredy taken steps to remedy the problem yet I have noticed
couple of fish hanging around the waterfall more than usual which a
know is a sign of ammonia burn. I hope is not the same for the fish in
question. If anyone has any idea what it might be and what treatment to
apply PLEASE HELP.
--
IceEros
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