2020–2021 BCSC Basic and Clinical Science Course™
8 External Disease and Cornea
Chapter 10: Infectious Diseases of the External Eye: Microbial and Parasitic Infections
Phthiriasis is a venereally acquired crab louse (Phthirus pubis) infestation of coarse hair in the pubic, axillary, chest, and facial regions. Adult female crab lice (Fig 10-8) and immature nits on the eyelashes are a cause of blepharoconjunctivitis.
Demodex folliculorum and Demodex brevis inhabit normal superficial hair and eyelash follicles and deeper sebaceous and meibomian glands, respectively. An increased number of these species in the facial glands is associated with rosacea (Fig 10-9). Eyelash colonization increases with age and may be associated with blepharoconjunctivitis.
Cox FEG, Wakelin D, Gillespie SH, Despommier DD, eds. Parasitology. 10th ed. London: Hodder Arnold; 2005. Topley & Wilson’s Microbiology and Microbial Infections; vol 6.
Tu EY. Acanthamoeba and other parasitic corneal infections. In: Mannis MJ, Holland EJ, eds. Cornea. Vol 1. 4th ed. Philadelphia: Elsevier; 2017:976–985.
Figure 10-8 Crab louse (Phthirus pubis). (Wet mount, original magnification ×200.)
Demodex species. (Wet mount, original magnification ×100.)
(Courtesy of Elmer Y. Tu, MD.)
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.