Blepharitis: Always Remember Demodex

Purpose: To determine the incidence and density of Demodex species on the eyelashes of subjects with normal eyelids, anterior blepharitis (AB), meibomian-gland dysfunction (MGD), and mixed blepharitis (MB). Materials and Methods: One hundred and fifty consecutive patients diagnosed with AB, MGD, and MB were recruited. An additional 50 individuals were recruited who were free of lid and margin disease to serve as a control group. All patients underwent a standard eye examination. Data on ocular symptomatology were gathered. Digital photography was performed of the lid margins. Lash sampling was performed by epilating the lashes and the lashes were checked for Demodex based on morphology using light microscopy. The total number of mites were tabulated for each eye. Comparison between the affected eyes and the control eyes was performed. Data were analyzed using the Chi-square test. Results: A total of 200 patients were included. Twenty percenth had AB, 40% had MGD, and 40% had MB. The incidence of Demodex infestation was 90% in cases of AB, 60% in MGD cases, and 90% in MB cases. The incidence of Demodex in control subjects was 18%. Conclusions: The incidence and density of Demodex infestation was highest in patients with AB and MB. Lid irritation and presence of cylindrical dandruff were indicative of a high-density infestation. These signs should alert the clinician to treat concomitant Demodex infestation.