The eye fly is commonly found in the most unkempt of places; the inn with the worst reputation, the brothel under the docks, the king’s secret and personal torture chamber hidden in the walls. If you spend at least eight hours sleeping in an exceptionally dirty location then you are likely to fall prey to an eye fly crossing the surface of your face. Roll 1d12, on a 1 you have played victim to the eye fly’s searching.
An eye fly will lay a dozen microscopic eggs in the left most canthus of your eye, where your tears rest and have the sweetest taste. In a day they will hatch into eye flay maggots. It will take them 1d6 days to eat out the surface the inner eye socket. Eye fly larvae are marked by a grey, stiff body covered in oily black hairs that will scrape and tear all it touches, causing a penalty to checks related to seeing clearly. In the middle of that infectious period the larva will chew through the nerve stem of your eye, severing the connection and letting loose your eye to roll across the floor.
On the final day of the infection the larva will have completely aged into adulthood, and fly from the socket of your eye like bats from a bell tower at twilight.