Hi there,
I agree with Sue about giving up the sugar, but I have also noticed eating too much fat has caused excess mucus to build up in my eyes (after a night of eating particularly fatty foods). Dairy products too cause mucus to build up.
To add to this, try washing the eyes with mild warm salt water, (you can use an eye bath)then rinse with clear water after. I have done this every day for years and it keeps the eyes nice and clear and cuts down the mucus. I would also suggest drinking plenty of water.
Hope your eyes are better soon.
Warm Regards,
Joy.