Fungal and Parasitic Infections of the Eyelid Margin
Demodex is a genus of mites that are normal commensal acarian parasites of humans. On slit-lamp biomicroscopy, their presence is suggested as waxy “sleeves” around eyelashes (Fig 10-10) or as “cylinders” extending from sebaceous glands of the eyelid margin. The role of these parasites in the pathogenesis of blepharitis is unclear, but some patients may experience an inflammatory response with infestation. The infestation may respond to diluted tea tree oil applied to the base of the eyelashes. Other organisms that survive on lipids of eyelid glands, such as Malassezia furfur, have also been implicated in certain types of blepharitis.
(Courtesy of Elmer Y. Tu, MD.)
A focal granuloma or dermatitis affecting the eyelid or conjunctiva can be caused by very rare infections, including
Lice infestation of the eyelids and eyelashes, also known as phthiriasis palpebrum, is an uncommon form of conjunctivitis or blepharitis affecting adolescents and young adults and is caused by the pubic louse and its ova. In rare instances, pediculosis involves the ocular region by localized extension of head or body lice (Pediculus humanus capitis or Pediculus humanus corporis, respectively). Mechanical removal of the lice and nits (eggs) can be performed with jeweler’s forceps, but pubic hairs are usually treated with a pediculicide. Any ointment can smother the lice and should be applied twice daily for at least 10 days, because the incubation period (of the nits) is 7–10 days. Periodic reexamination is recommended over 10–14 days to detect recurrence and remove any new nits. Bed linen, clothing, and any items of close contact should be washed and dried at the highest temperature setting (at least 50°C).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.