This 26 year old woman was referred to the eye clinic because of a left chronic ocular irritation. On slit-lamp examination, the above picture is seen.
a. What is the cause of her left chronic ocular irritation?Pubic louse (Phthirus pubis) and multiple eggs attached to the eyelashes.
Phthirus pubis is a blood sucking parasites which belongs to the order Anoplura. It is most commonly found in the groin and can be sexually transmitted. Other areas where it can be found include axillae, eyelashes and eyebrows. It contains claws that allow it to cling to the hairs of these areas.
The louse lays its eggs within a few days of becoming sexually mature. The tiny, white eggs or nits are cemented to the base of the hair shafts. After hatching, the nymphs pass through two or three stages (instars) before reaching adulthood.
b. How would you treat this condition?
Several options are available:
- manual removal of the lice and nits with forceps
- applying petroleum to the edges of the lid margin can kill the lice but has no effect on the nits
- anticholinesterase such as physiostigmine 0.25% ointment can be used to kill the lice
- malathion 1% which is an organophosphorus can kill both the lice and the nits.
The patients should be referred to the STD (sexually transmitted disease) for further physical examination and possible treatment.
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