When my mare had the habronema fly larvae in the eyes, (she had it twice- I will never leave her without a mask again, even for a week) She had runny teary eyes that had some white drainage, but then looking in the corner of her eye was this gritty , yellow sandy looking stuff, and it really adhered to the mucosa. I had to have the vet come and tranq. her, and we really cleaned out the eye mucosa, and then I had to wash the eye with saline drops every day, and some optic ointment with a steroid and antibiotic applied also. It took a long time to clear up. They say the horses can get it in the male genitalia too. Beth