Multiple Eyelid Signs are Suggestive of Demodex Infestation

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.

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.

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).

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.