I just saw, and have had the pus in eye lid pimple issue as well as persistent red and dry eyes and inflamed lids.
I am unofficially the foremost authority on POIS red eye. I have dozens of pictures of my single affected red eye and swollen eye lids (that occasionally went to both eyes), and in fact it was the first major symptom that put me on notice that something had changed in my body when my POIS first emerged two years ago.
Something about POIS affects the meibomian glands which line your eyelids. The glands (the are dozens of glands on both your upper and lower lids) are responsible for release of the oils (lipids) that coat the tears released by the lacrimal glands. When the glands get blocked or clogged the oil in the gland solidifies, and doesn't release properly when you blink, so the normal tear does not spread across the eye surface fully or remain on it. Result is dry red eyes. In addition, the blocked glands themselves get infected/irritated causing the angry swollen lids.
It probably is a meibomian gland, not the tear duct that got infected and pus filled.
Relatedly, the blocked glands appear to cause or be paired with increased bacterial growth on the lids and lashes. This is the condition known as blepharitis.
Most opthamologist will easily diagnose the blepharitis and prescribe an antibacterial ointment as well as an eyelid scrub (e.g. Ocusoft) to work on the blepharitis. They may also give you steroid drops which will clear the red eye for a time.
HOWEVER, unless you take steps to unblock the meibomian glands in addition to a scrubbing routine, you will not get relief. To unblock the glands, they must be expressed (squeezed to release contents). There are ways to express the glands at home, but if you are long affected, chances are you would be best served going to a dry eye specialist who has inoffice instruments that heat and then deeply express the blocked glands beyond what you can do manually.
I went to an specialist and did:
https://dryeyeandmgd.com/dry-eye-and-mgd-treatments/lipiflow-treatment-leading-cause-dry-eye/***** cost 800 bucks. And it was worth it. After the inoffice expression, you need to adopt a complete 2x daily regimen of eye washing and at-home gland expression.
For daily washing, I use a tea tree based eye scrub on just the lashes and eyelid margins, NOT the entire eyelid as it will irritate them. (sometimes I use OcuSoft instead) Then I use a cloth to wipe the lashes in one direction (from nose to ear to try and debride the eyelash) with a little bit of pressure, before pat drying my eyes.
Then I do 5 minutes of hot compress on the eyes (microwave a tied off sock filled with uncooked rice for 2 min), followed by manual expression of both eyes, upper and lower. Have to do the hot compress because you can't express the gland oil unless it is heated.
Here's a link that shows you one way to express the glands, I was shown that it is more effective to apply light pressure with your finger tips and hold for 5 seconds at 4 or 5 points along each lid margin, but this will still work:
https://www.youtube.com/watch?v=hOGwoBD_-sY \
Pro tip: you will know it's working if your eyes all of sudden feel wet and oily.
I also went the extra step and bought this tool to scrub and express the eyelids every few days:
https://www.nusightmedical.com/Finally, it is important that when using computer, watching TV etc, that every 10 or 15 minutes you look away into the distance and blink a bit for 20 to 30 seconds. Also good to use preservative free eye drops/tears over the course of the day.
