At first test, a Demodex infestation could look an awful lot like your run-of-the-mill dry eye. Both patients will have reduced Schirmer test scores and elevated ocular surface disease index (OSDI) rates, according to newly published research in the journal Eye & Contact Lenses. A Turkey-based research team determined that the presence of the notorious lash mites is associated with the same Schirmer test and OSDI scores, as well as average age values, as patients with newly diagnosed dry eye disease. 

The investigators looked at 168 eyes of 84 dry eye patients— all with Schirmer test scores less than 5mm/min wetting—between ages 40 to 68, and performed three diagnostic examinations: OSDI, the Schirmer test and a microscopic eyelash evaluation. For those whose lash evaluations exposed a Demodex infestation, the average Schirmer test score was 2.1mm/min, the OSDI questionnaire score was 61.82 and the mean age was approximately 55. For the patients without a Demodex infestation, the average Schirmer test score was 6.6mm/min, OSDI was 40.96 and the mean age was approximately 49. 

To evaluate for Demodex, the clinicians extracted two eyelashes from the inferior eyelids of each eye, and the sample was immediately brought to the microbiology laboratory in the slides by pouring two drops of saline. If any one of the four lashes was found to show infestation, the patient was included in the Demodex-positive group.

Each of these patients was treated with lid hygiene including tea tree oil shampoos.

Determining Demodex infestation as a factor in dry eye disease with multifactorial etiopathogenesis, can assist in the early treatment and prevention of the progression of dry eye symptoms, the study notes. 

Ayyildiz T, Milletli Sezgin F. The effect of ocular Demodex colonization on Schirmer test and OSDI scores in newly diagnosed dry eye patients. Eye Contact Lens. June 29, 2019. [Epub ahead of print].