Goose with one squinty eye and no visible injury. What could be causing it?

[hannanah]

My 2 yo African brown gander has been squinting one of his eyes shut off and on for several months. I believe it's always his right eye. He blinks as if there's something stuck in his eye but I haven't noticed anything visibly wrong. Then when I'm starting to get worried he will go back to normal.

Does anyone know what could cause this? I've been applying Terramycin but haven't noticed any great effect.

Thanks

 

[Eggcessive]

Can you have someone hold while you look into the eye and examine the third eyelid? Take a picture to post here. There could be a speck of something or a seed in there irritating it. Flush the eye with saline and keep applying the Terramycin twice a day.