The demodex: the non-incriminated suspect of chronic blepharitis

Abstract

We report the case of a 55-year-old patient, followed in ophthalmology for recurrent chronic blepharitis for 5 years. The ophthalmological examination found a 20/20 visual acuity in both eyes, conjunctival hyperemia, instability of the tear film with a BUT less than 5 seconds, as well as the presence of a crusting anterior blepharitis, mainly located at the level of the upper eyelid, with microscopic evidence of cylindrical dandruff at the base of the eyelashes, corresponding to demodex. The patient was treated for blepharitis, including multiday palpebral hygiene, based on palpebral massage by hot compresses and combinations of eye-drops and ointments based on antibiotics and corticosteroids, all associated with an additional treatment with artificial tears. Eye demodex is a common condition, but clinically under-diagnosed; demodex mites have been incriminated in the physiopathology of anterior blepharitis (D.folliculorum) and posterior blepharitis (D.Brevis). The folliculorum finds its main habitat at the base of the eyelash follicle, where it feeds on epithelial cells, causing direct mechanical damage. Since demodex does not have excretory organs, the undigested residues are regurgitated, and then combine with epithelial cells, keratin and eggs to form the cylindrical deposits of the eyelashes, characteristic of the presence of demodex. D.brevis was associated with dysfunction of the Meibomus glands, where it causes a primary mechanical blockage of the glandular orifice.