On my ride to work, I headed through the Clarence MTB Park (Meehan Ranges). I had been wearing dark riding glasses but when I got into the dense trees, I couldn't see the track properly. I took off my glasses to see the rocks & roots more easily but I managed to scratch my left eye as I rode through a branch. I got a bit of 'stuff' in my left eye & it was really irritating.
20 mins later at work I managed to wash the 3mm bit of stuff out but my eye was very red & inflamed. I went to an optometrist & they found a scratched cornea & I had scraped of some of the top layer (whatever bit that is) - which they found by putting dye in my eye.
The lesson from all that is wear clear riding glasses in the dark areas for protection.