Palpebral and facial skin infestation by Demodex folliculorum.

Purpose: To evaluate facial Demodex densities in participants with varying severities of blepharitis secondary to Demodex folliculorum assessed by the highest number of cylindrical dandruff on one lid.
Methods: This double masked cross-sectional study included 58 participants [19 control, 21 mild/moderate and 18 severe Demodex blepharitis] who underwent a standardized skin-surface biopsy and a lash epilation for each lid to obtain the forehead Demodex densities and the overall lash mite count, respectively. Also, facial photographs were taken to evaluate facial erythema and dermatological conditions. The Ocular Surface Disease Index [OSDI], non-invasive break-up time [NIBUT], tear meniscus height [TMH], bulbar conjunctival redness as well as additional questions on watery eyes, ocular itching and itching along the lids were assessed.
Results: Both mild/moderate and severe Demodex blepharitis groups were over the cut-off value [≥ 5 mites/cm ² ] that confirms a facial demodicosis (mild/moderate: 5 ± 1; severe: 6 ± 1) while the control group was below it (2 ± 1). Thereby, group comparisons showed that an increased severity of Demodex blepharitis was associated with higher forehead mite densities (p = 0.002) and increased lash mite count (p < 0.001). The degree of facial erythema was also positively correlated with forehead mite densities (rs = 0.31, p = 0.02). When compared to the controls, the mild/moderate group had more watery eyes (X ²  = 6.54, p = 0.02), a lower TMH (U = 100.5, p = 0.006) and the severe group had more itching along the lids (X ² = 4.94, p = 0.04). The other ocular signs and symptoms [NIBUT, bulbar conjunctival redness, OSDI] were not affected by the severity of Demodex blepharitis (p > 0.05).
Conclusion: Palpebral and facial Demodex infestation can co-exist, as the presence of blepharitis secondary to Demodex is associated with increased facial mite densities.
Competing Interests: Declaration of Competing Interest SA has received honorarium for conferences/consulting from Allergan and Shire. EB has received funding from Alcon, Allergan, Canadian Optometric Trust Fund, I-Med Pharma Inc, Shire and honorarium for conferences/consulting from Akorn, Alcon, Allergan, American Academy of Optometry, Canadian Association of Optometry, CooperVision, Labtician, Jobson Publishing, Novartis, Santen, Shire.
(Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)