Refused critical illness cover due to misdiagnosis? What can I do?

Hi,
Back in Oct 2012 I had a 2 short spells when my vision was blurred when I woke up for up to 30 min at a time. I was sent to Opthomologist. He could not find anything. Sent me for ECG which came back fine too. That was end of the story. I was under impression that everything is fine because no further tests were conducted. Since then I never had a problem with blurred vision again. I applied for CIC few months ago. Reported all the problems, they contacted GP for further details and on the report it says "Provisional diagnosis: Amaurosis fugax". I was never told about this provisional diagnosis. Reading about it this is something which can lead to blindness, stroke etc. But also should be treated! With me they have done a ECG which came back fine and I am guessing they concluded that it is not that, nor nothing serious and did not do any further action.

Now the question is what can I do about it? Because if I really have it I should be treated for that. If I don't which seems to be correct can I request it to be corrected by the GP or Opthomologist. I feel I am the one who loose out now because Opthomologist was playing a guessing game.

Another option is to wait few months until 5 years passes and then most insureres won't ask for anything which was over 5 years ago.

Any advice appreciated. Thanks