Thread by @DGlaucomflecken

It's about time the wicked Queen Acanthamoeba started getting some press. She's a lot sneakier than her blithering oaf of a husband. The queen loves water, so if you shower or swim in contacts or if you clean your contacts with tap water, she will find you and she will hurt you.

https://twitter.com/NEJM/status/1151907153764114434

Contact lens abuse can lead to minor corneal trauma (small epithelial erosions), which provides an easy avenue for acanthomoeba to infiltrate the cornea. The queen has 2 forms: Trophozoites and cysts. The trophs are mobile, they sneak into those erosions and establish residence

Initial symptoms are mild. A little discomfort, a little irritation, nothing major...until the Queen finds your corneal nerves. Then, you get searing pain out of proportion to clinical findings. Your vision may be fine, but if feels like somebody is setting your eyeball on fire.

Because ophthos may not see anything initially, diagnosis is often delayed while the pain causes you to seriously consider auto-enucleation. Eventually, a ring infiltrate or hypopyon shows up, a corneal scraping or confocal microscopy is finally done, & the diagnosis is made.

So now you think, "Phew! now we can blast it with antibiotics for a week and get rid of it." Not so fast. For as many trophozoites as she has running amok in your corneal nerves, she has just as many double-walled cysts able to resist almost anything you throw at it.

Usually, a combination of multiple eye drops (PHMB, Chlorhexidine, brolene) are administered hourly, sometimes for MONTHS before the infection is cleared. Stop the drops too soon and the cysts will rise from the ashes and re-establish infection and the whole thing starts over.

Sometimes, despite aggressive treatment, the Queen persists, thinning the cornea, threatening to perforate. If perforation occurs, the Queen, her idiot husband, and all their horrible children have access to the sweet sweet humours that lay within.

Therefore, as a last resort, sometimes the Queen must be cut out, a new cornea is grafted on, and everybody prays that cysts aren't hiding in the fringes, waiting to infect once more.

...or you could just not swim or shower in your contacts.