My Welsummer bantie had it this Fall. I took her to a bird vet who said that it was conjunctivitis--an extremely common bird eye infection (in wild AND domestic birds) to get. It's extremely contagious, but it can be treated easily, with antibiotics. It will usually lead to blindness if left untreated.
She prescribed
Neo-Poly-Bac opthamologic ointment for animals. Throwing antibiotics at everything really isn't effective- You need specific
opthamologic anti-biotics that include anti-inflammatory meds to treat conjunctivitis in birds. Neo-Poly-Bac comes in a tube and is a thick petroleum-type ointment (definitly get the
ointment and not the suspension. The suspension is watery and doesn't adhere to the eye.)
With very clean hands, you'll need to gently force open the lid (they have three eyelids, so make sure you get them all open!) then carefully squirt a little line of the ointment directly across the eyeball horizontally. Gently let the eye close on the line of ointment then open it again to make sure it's doused pretty well and all over both the eyeball and the lids. It doesn't hurt them but obviously they don't love their eyeball being messed with! lol
You'll need to do this
every 12 hrs for 7 days. In two or three days, the eye will probably look completely normal, but she said to
make sure to treat the whole 7 days because the bacteria is probably not all dead and they could have a relapse, this time with resistance to the meds!
Our Rhode Island Red bantie also got conjunctivitis a few weeks later (prior to getting Marek's and dying

), and I treated her with the same ointment. Worked perfectly for her too.
One of my Ameraucanas started holding one of her eyes half open the other day and I immediately started dosing her. She hasn't shown any signs since.
That vet charged (READ: ROBBED!!!) me: $32 for a 3.5g tube
but I found it online for $13 @ petmeds.
http://www.1800petmeds.com/Neo+Poly+Dex+Ophthalmic-prod10184.html
[Most vets (around here, at least) will price-match, so if you print out the petmeds page and take it in to your nearest vet, they should match it.]
BTW- you should keep it in a ziploc (ie, dry) in the frig. The ointment, like any other med, will lose efficacy over time but if you keep it in the frig, it keeps the potency longer.
I keep a tube around all the time now, in case I notice an eye looking suspicious. 1/7-ounce of prevention is worth a pound of cure!!!
Good luck!!
Holly