Allergie
– most obvious answer, but not necessarily most common
– signs: swollen/puffy eyelids, watery eyes, bumps under eyelids (seen by your doctor), diffuse and more intense itch
Blepharitis (blepharo- = eyelids, -itis= inflammation)
– so, inflammation/irritation of eyelids, very common
– could be due to mild bacterial infection or blockage of glands at the base of eyelashes
– signs: redness along eyelid margin, itchiness usually concentrated at eyelid margin or at the corners of your eyes but not as intense as with allergies, also watery eyes