Can blepharitis cause edema under the eye?

Occasionally: If the blepharitis is chronic or severe or you are unusually sensitive, tissues surrounding the inflammation can leak fluid which is carried downwards in the deeper tissues to cause swelling lower in the lid. See your ophthalmologist for the most effective treatment.

Yes: Yes. Sometimes the body's reaction to "plugged up" oil glands in the eyelid can cause swelling and redness around the eye. Sometimes bacteria living near the oil glands/base of the eyelashes can also cause swelling and redness around the eye. Usually this can be treated with a combination of antibiotics and/or steroids (ointment, eyedrops, or pills).