Elevated levels of Demodex have long been associated with blepharitis. With this in mind, Austrian researchers sought to determine the prevalence of Demodex mites in eyelashes of patients with ocular discomfort and to evaluate associated lid margin and meibomian gland changes. They found that the prevalence of mites is high and associated with anterior and posterior lid margin changes, suggesting a pathogenic role in blepharitis and meibomian gland dysfunction.

This case-control study evaluated 229 patients and assessed the associations of mite infestations with dry eye and lid parameters. Lid margins were evaluated for scales, vascularization, Marx line, meibum expressibility and quality and meibomian gland dropout.

The team identified Demodex mites in 40.2% of patients suffering from ocular discomfort, with an average mite count of 3.3 ± 2.9 per patient. They note that mite infestations were associated with the presence of significantly more cylindrical sleeves, a higher Marx line score and a lower quality of meibum. They add that there were no significant associations with meibum expressibility and meibomian gland dropout.

While Demodex are common in patients with ocular discomfort, the mean mite count per patient in this Austrian population is lower compared with previously published data from Asian regions.

Rabensteiner DF, Aminfar H, Boldin I, et al. Demodex mite infestation and its associations with tear film and ocular surface parameters in patients with ocular discomfort. AM J Ophthalmol. March 15, 2019. [Epub ahead of print].