Having read through these pages a week ago and then again today I will offer a different opinion to what a lot of other people have said here. In particular I am wary of claims here that conjunctivits had been cured in "hours or days" due to the use of ACV.
I am on day 14 of acute keratoconjunctivitis (this is the viral version). It is now (very) slowly improving and the symptoms are starting to go away including the red eyes. I was told by the ophthalmologist that it will take a number of weeks for me to fully recover and as it is a virus like the common cold there is no cure for it, is is just a case of waiting for it to run it's course whilst trying to maintain comfort as much as possible.
Anyway, one week ago ago when my conjunctivitis was in full swing and I was more naive about such matters... I found this site and the claims that ACV with the mother was having positive effects on dealing with conjunctivitis. With an open mind I obtained a bottle and used it diluted but still with a bit of a sting, on my eyes, 3 - 4 times a day. I repeated this for about 5 - 6 days with the aim of the reduction of the red eye symptons and of some pain in my eyes. After a number of days it became obvious the ACV was not doing anything positive and so having seen no effect whatsoever I stopped use.
Thinking about it now I am not sure from a biological / medicine point of view what specifically in ACV is supposed to do to be effective against conjunctivitis. I am assuming its antibacterial proerties are considered to have a role in this... but would something with antibacterial properties help kill a virus?? I am aware of the very real health benefits of plants and so called alternative medicines and I will use them 100% every time in favour of modern medicine IF they provide me with benefits. However of all these people claiming ACV works, they can't all be wrong ... so I guess what works for one particular set of symptoms will not work for another similar but different set of symptons.
If you have conjunctivits I would suggest that you go and insist on seeing an OPHTHALMOLOGIST and insist on getting your eyes checked properly. In my case I first went to see a nurse at my local doctor surgery who was dismissive and not especially helpful. Then two days later when the symptons were significantly worse I went to see a doctor. The doctor was slightly more helpful but did not have the specialist tools or knowledge to make a particularly useful diagnosis other than a general comment about using eyedrops and it will go away after a few days.
It was only after I saw an ophthalmologist at the eye casualty and quite detailed study of my eyes that I was properly diagnosed with the problem that was one of the reasons I tried the ACV solution in the first place: I had as part of the conjunctivitis a "pseudomembrane" develop on all 4 of my inner lids and it was this that was causing excruciating pain when my eyes were closed for more than a few seconds. Anasthetic was dripped into my lids and each of these 4 pseudomembranes was surgically removed there and then. I was told to continue using liquid gel tablets as well as some anti viral eyedrops which I have already been using... I am told this will help with the keeping eyes closed and therefore sleeping, the other symptons of conjunctivitis will improve over time.
So.. that is my story. Feel free to try ACV anyway, it might work for you, it might not. Maybe you don't even have conjunctivitis after all, just a couple of the symptoms of it!