The lid margin and Demodex

Purpose Demodex infestation can be associated with blepharitis. To date, the pathogenic potential of these mites in Meibomian Gland Dysfunction (MGD) remains unclear. The purpose of this study was to determine the relationship between the prevalence of Demodex in eyelashes and changes of the anterior and posterior lid margin. Methods Between October 2011 and March 2012, 229 consecutive patients with ocular discomfort from the dry eye unit of the Ophthalmological Department, Medical University Graz, Austria, were investigated for the presence of Demodex mites on sampled eyelashes. Lid margins were evaluated according to scales, vascularisation, Marx line, expressibility and quality of meibomian gland secretion. Results Demodex spp. were found in 40.2% of patients with ocular discomfort. The presence of Demodex mites was significantly associated to blepharitis. No difference in Demodex occurrence was found between the sexes. Compared to the non‐infested, patients with Demodex mites had significantly more scales formed as sleeves, a higher Marx line score and a lower quality of the meibomian gland secretion. No significant association was observed with vascularisation of the lid margins and expressibility of meibomian glands. Within the infested patients the mean Demodex count per patient was 3.28 ± 2.89 and Demodex count was found to increase with increasing age. Conclusion Demodex mites are associated with changes of the anterior and posterior lid margin and therefore may play a pathogenic role in blepharitis and MGD.