Ocular Demodicosis (Demodex Infestation) Workup

Updated: Oct 30, 2017
  • Author: Manolette R Roque, MD, MBA, FPAO; Chief Editor: Hampton Roy, Sr, MD  more...
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Workup

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.

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Imaging Studies

By visualizing the metazoan parasite under high-power magnification, a definitive diagnosis can be made.

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 cylindrical dandruff of epilated eyelashes. [7]

Electron microscopy has been used to visualize the organism.

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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.

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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. [1] 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 t 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 Dem 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 e 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), 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.
Demodex folliculorum. Demodex folliculorum.
Demodex along the shaft of the cilia. Demodex along the shaft of the cilia.
Demodex along the shaft of the cilia (higher magni Demodex along the shaft of the cilia (higher magnification).
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