Well I have never had it, but my wife had a very severe episode a few years ago. Very painful and she went blind in one eye. After applying steroids every hour, day and night, for 3 weeks her sight returned. Very very nasty indeed. I would have thought that there is usually an underlying reason why it appears and this might be a reason why a medical may be difficult. Speak to medical branch and they will advise. It is also more commonly called anterior uveitis.