I've been having some trouble with Dapper Dan's eyes the last couple of years. I've been using allergy drops, which helps. And he wears the Cashel fly mask. His eyes ran almost constantly and I had to wash his face every day. The eye lids were quite red. On a tip, I ordered a sun visor from this company. He's been wearing it for about 3 weeks and his eyes are almost totally cleared up! I think the sun is more of an issue than pollen. Or perhaps this one filters more pollen. It is very well made and the company was easy to work with. I ordered the Miniature size, but they will custom fit to your measurements. http://www.equinesunvisor.com/