Many thanks for the interest everyone has shown, and especially to Eugene who has been emailing me with great information and reassurance! How lucky am I to have an expert in the field as a friend! I would just add that Alyssa didn't have conjunctivitis - her eyes were a little red and watery looking (like with a cold), but otherwise perfectly normal... My doctor has suggested it is most likely that she developed the infection secondary to sinusitis, but again she hadn't complained of any pain in that area. It could also have been due to allergy, a bite or a foreign body in the eye i.e. they have no idea! I believe this is most common in children under the age of 5, yet Alyssa is nearly 10...  She is improving daily - up until yesterday she was seeing 2 images, but today is back to one - yee-ha! - and the swelling is getting less every day. Thanks again for your kind thoughts.