The presence of demodex mites is determined either ex-vivo, by pulling out random eye lashes and examining them under a microscope, or in-vivo, with a confocal microscope. Larvae, teenage, and adult mites can easily be seen under a microscope.
Demodex mites may also be present if there is debris in the eye lashes, or, if there are collars at the base of the eye lashes. Sometimes when demodex are present, eye lashes are colorless, or their roots are black.
The population of demodex mites increases as we age. Infants have few if any demodex mites in their lashes, whereas virtually all people over 65 have demodex in their lashes.
Normal size colonies of demodex are usually harmless, but large populations can lead to disease. Allergies to demodex, their debris, or the bacteria they harbor in their bodies, can cause blepharitis, demodicosis, allergic conjunctivitis, and related problems, all of which require treatment.
References
In vivo confocal microscopy as a novel and reliable tool for the diagnosis of demodex eyelid infestation
Matthieu Randon, Hong Liang, Mohamed El Hamdaoui, Rachid Tahiri, Laurence Batellier, Alexandre Denoyer, Antoine Labbé, Christophe Baudouin.
British Journal of Ophthalmology
2015;99:336-341 doi:10.1136/bjophthalmol-2014-305671
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Methodologies to diagnose and monitor Dry Eye Disease: report of the Diagnostic Methodology Subcommittee of the International Dry Eye WorkShop (2007)
No authors listed
The Ocular Surface
2007 Apr;5(2):108-52.
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Under the lash: demodex mites in human diseases
Lacey N, Kavanagh K, Tseng SC.
The Biochemist
2009 Aug 1;31(4):2-6
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