Multiple Eyelid Signs are Suggestive of Demodex Infestation

PURPOSE: To determine the signs associated with Demodex infestation in blepharitis patients and the rates of eyelash Demodex colonization among blepharitic patients and healthy individuals in Thailand. PATIENTS AND METHODS: This was a prospective, case–control clinical study. Eighty-three controls and 43 blepharitic patients were consecutively enrolled from Walailak University Hospital. Each patient answered a questionnaire, underwent a complete eye exam, and had four lashes from each eye epilated; eyelashes were directly examined under a light microscope. Ocular signs, including types of eyelash debris (waxy debris, scaly debris, or cylindrical dandruff (CD)), erythema and telangiectasia of the eyelid, were noted. RESULTS: Demodex infestation was observed more frequently among patients with blepharitis than among controls (67.4% in the blepharitis group, 26.5% in the control group, p-value <0.001). The participants with Demodex infestation were 5.7 times more likely to have blepharitis than the controls (odds ratio 5.74; 95% confidence interval 2.57–12.82, p-value <0.001). Clinical signs that were significantly (p-value <0.05) related to demodicosis were lid erythema, lid telangiectasia, and any type of eyelash debris (scaly, waxy, or CD). CONCLUSION: In contrast to previous studies that found only CD to be highly associated with eyelash demodicosis, we found multiple suggestive signs: any kind of debris on eyelashes (scaly, waxy, or CD), eyelid erythema, and eyelid telangiectasia. Approximately one-quarter (26.5%) of the studied population had asymptomatic mite colonization. Demodex infestation should therefore always be on the list of possible etiologies when treating patients with blepharitis or other ocular surface-related problems.