Laboratory Studies
Diagnosis of demodicosis is made on a high index of clinical suspicion.
Occasionally, nasal skin scrapings may be requested to rule out the possibility of acne rosacea.
Imaging Studies
A definitive diagnosis can be made by visualizing the metazoan parasite under high-power magnification.
Imaging systems using high magnification that allow photographic documentation and grading of demodicosis now are commercially available.
An epilated lash examined under low-power magnification may demonstrate the organism.
Adding a fluorescein solution after mounting further helps in detecting and counting the mites that are embedded in the cylindrical dandruff of epilated eyelashes. [8]
Electron microscopy has been used to visualize the organism.
Procedures
Slit lamp biomicroscopy involves carefully removing a collarette at the base of an eyelash using flat ophthalmic forceps. The tail of a Demodex may be visualized as a translucent strand at 16x magnification.
Histologic Findings
All reported histologic sections of lid follicles infested with D folliculorum show distention and thickening. Coston claims that less than half the specimens he observed showed perifollicular lymphocytic infiltration. [2] Follicular inflammation produces edema and results in easier epilation of the eyelashes. It also affects cilia construction, and the lashes are observed to be more brittle in the presence of demodicosis. Dermal changes seldom extend beyond the perifollicular epidermal area, although epithelial hyperplasia associated with follicular plugging is often encountered.
Eyelid section shows Demodex folliculorum (M) in the hair follicle. Note mite mouthparts (arrow) embedded in epithelium and straplike layers of keratin (hematoxylin and eosin, X400). Reprinted with permission from Elsevier Science.
Section of sebaceous gland of an eyelash shows Demodex brevis (M). Note gland cell (C) destruction (McManus, X375). Reprinted with permission from Elsevier Science.
Cross-section through small hair follicle of the eyelid. Note distension, hyperplasia, and moderate epithelial keratinization caused by the activities of Demodex folliculorum (arrow) (hematoxylin and eosin, X375). Reprinted with permission from Elsevier Science.
Section of eyelid shows eyelash (L), cuffing (C), and small segment of Demodex folliculorum (M). Note layering of cuff (Masson, X275). Reprinted with permission from Elsevier Science.
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Illustration of Demodex folliculorum. Reprinted with permission from Antoine Morin, BIODIDAC, University of Ottawa.
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Eyelid section shows Demodex folliculorum (M) in the hair follicle. Note mite mouthparts (arrow) embedded in epithelium and straplike layers of keratin (hematoxylin and eosin, X400). Reprinted with permission from Elsevier Science.
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Section of sebaceous gland of an eyelash shows Demodex brevis (M). Note gland cell (C) destruction (McManus, X375). Reprinted with permission from Elsevier Science.
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Cross-section through small hair follicle of the eyelid. Note distension, hyperplasia, and moderate epithelial keratinization caused by the activities of Demodex folliculorum (arrow) (hematoxylin and eosin, X375). Reprinted with permission from Elsevier Science.
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Section of eyelid shows eyelash (L), cuffing (C), and small segment of Demodex folliculorum (M). Note layering of cuff (Masson, X275). Reprinted with permission from Elsevier Science.
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Demodex folliculorum.
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Demodex along the shaft of the cilia.
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Demodex along the shaft of the cilia (higher magnification).
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Backsides of numerous pubic crabs with infestation of the lashes and secondary blepharitis. Reprinted with permission from HD Riley, OD, Indiana University School of Optometry.
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Phthiriasis (Phthirus pubis) pubic crab lash infestation and secondary blepharitis. Reprinted with permission from HD Riley, OD, Indiana University School of Optometry.
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Phthiriasis (pubic lice). Reprinted with permission from HD Riley, OD, Indiana University School of Optometry.
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Demodex infestation is an under diagnosed cause of chronic blepharitis. Image courtesy of Rendia, Inc. Copyright 2017 Rendia, Inc.
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Blepharitis secondary to Demodex infestation. Image courtesy of Rendia, Inc. Copyright 2017 Rendia, Inc.
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A novel in-office treatment using a mechanical rotating handpiece with a microsponge tip combined with PolyaminopropylBiguanide foam solution removes oil, scurf, and debris; exfoliates the eyelids, and claims to decrease Demodex infestation. Image courtesy of Rendia, Inc. Copyright 2017 Rendia, Inc.
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Intense pulsed light. Courtesy of OPTIMED (https://www.optimed.co.uk/), E-referral and patient engagement platform.
