DEMODEX PARASITES AND CHRONIC BLEPHARITIS

INTRODUCTION: In the current issue of 'Harefuah', Livny et al present an article on the prevalence of Demodex parasites in patients with chronic blepharitis and healthy controls in Israel. This prospective case controlled study describes the quantitative connection between the number of parasites found on 6-8 sample eyelashes and chronic blepharitis, one of the most prevalent conditions in the general population and especially prevalent in the ophthalmologist office visits. Blepharitis symptoms may vary from being asymptomatic, chronic condition, dry eye, and sometimes even a severe compromise of ocular surface with a morbid impact on patient quality of life. In recent decades, progress was presented in a number of published articles including one meta-analysis that connects blepharitis with Demodex and the treatment of both with tea tree oil. Also, two different species of Demodex were identified which prefer to inhabit different areas of the eyelid. While the presented data do indicate a quantitative connection between Demodex and blepharitis, questions are raised as to whether there is a causative relationship between them? Can Demodex cause chronic blepharitis as an only factor? Or a symbiotic parasite which proliferate in blepharitis by consuming the debris and byproducts of blepharitis? Is it both? Although many theories exist, the answer is yet to be proven, but the consensus today is to combine anti-Demodex products while treating refractory chronic blepharitis.