We check our sheep religiously twice a day everyday allowing plenty of time to assess each of them either up close or from a distance. Tonight I noticed that one, possibly two of the new girls (group of 10) had one squinty eye (hard to tell as they have black faces). The eye doesn't seem that swollen or have any discharge or have any cloudiness but it was starting to go darker and as they are new aren't tame enough to get up close.
I'm going to attempt to gather them up tomorrow, separate the ones affected and bring them in to have a closer look as it could just be debris, or something else. If pink eye I've read lots about different treatment options and that sometimes if not given time to mount their own response it can lead to repeated re-infections. I was thinking of putting them in a pen and bathing a couple of times a day with saline or mild salt water to keep the eye clean and lubricated and letting nature take its course (straight to the vets if progresses from mild). Other sheep in that field seem fine at the min as are the couple in the next field.