What is the eye condition called blepharitis?

Eyelid disease. Chronic crusting and erythema of the eyelid margin resulting in a red irritated eye. The cause can be multifactorial: abnormal meibomian glands, rosacea, seborrheic dermatitis.
Lid inflammation. This is a sometimes chronic condition in which the glands secrete oils that dry and cause inflammation on the lid margins. It is similar to dandruff. The lids become itchy, crusty and inflammed/red. Your ophthalmologist can recommend good treatment.