To treat an ingrown eyelash you can try applying a warm compress or cucumber slices or even some antibiotic ointments to help soothe the irritation, pain and redness of the ingrown eyelash.
To make a warm compress just take a clean washcloth and soak it in some warm water and wring it out and place the warm compress over your eyes.
Ingrown eyelashes usually go away on their own within 3 to 4 days.