Prevalence of Demodex folliculorum in a university-based population

The multifactorial aspect of dry eye disease remains challenging. Demodex folliculorum, a common ectoparasite on human eyelashes, may impact eye conditions such as blepharitis which can be a contributor to dry eye disease. Exploring risk factors for Demodex helps to raise awareness for early detection potentially improving ocular health.

Demodex folliculorum found on eyelashes can cause blepharitis. Its gelatinous debris at the base of the lashes, termed cylindrical dandruff is often associated with ocular itching. This study examined the prevalence of Demodex in a University population and assessed its relationship to symptoms of dry eye and itching.

Visual acuity, dry eye questionnaire (OSDI), non-invasive break up time (NIBUT), meibography, and slit-lamp examination were measured. When cylindrical dandruff was observed, lateral tension was exerted on two eyelashes to identify Demodex tails. Mann-Whitney tests were applied for comparisons, logistic regressions were applied to determine relationships, and chi-square, Fisher's exact test and Spearman correlation tests determined associations.

Of the 101 participants (mean age: 28 ± 12, range: 19-68 years, 90 females), 20% had dry eye (OSDI score ≥ 13 and NIBUT < 10 sec). Demodex tails/lash were significantly more prevalent in the upper (44%) compared with the lower eyelids (19%). Anterior blepharitis and cylindrical dandruff were significantly correlated with Demodex. Ocular itching (prevalence: 39%) was significantly associated with presence of Demodex only for the upper eyelids (p = 0.02). UODS was positively correlated (p < 0.001) with Demodex, cylindrical dandruff and anterior blepharitis.

There was a relatively high prevalence of Demodex among a university population. The prevalence of Demodex was not significantly different in those diagnosed with dry eye. Cylindrical dandruff and anterior blepharitis were significantly associated with the presence of Demodex, while itching was associated with presence of Demodex only for the upper eyelids. The UODS can be a valuable tool to add in future Demodex studies.