A man in his late 40s came in with blood shot and swollen eyes. 5 days ago while in the gym he rubbed his eyes after cleansers still on his hands. Since then each day both of his eyes were feeling worse with foreign body sensation, itchiness, pain and discharge. He went to urgent care 2 days ago, was given antibiotic drops and ointment, but felt it’s not helping. His conjunctiva (white part of eyes) were the most swollen that I had seen. Unfortunately I did not take a photo, but found one on the internet that quite resembled his eyes at the time as shown below.
Cornea (black part of the eye) was clear. At the time I thought this was toxic/allergic conjunctivitis, so prescribed a steroid drop to use 4 times a day for 7 days.
A week later, he came back, reporting improved symptoms (pain 3/10 from 5/10 previously), but still lots of discharge. This time, the swelling was gone, the redness almost resolved, but when I pulled his eyelid down, there were white pseudomembranes (fake membranes) in both eyes, more in one eye than the other. Below is again from internet, showing similar to what I saw.
Now this made me rethink the diagnosis. Pseudomembranes are often seen in infectious conjunctivitis caused by nasty bugs such as Corynebacterium diphtheriae, Neisseria gonorrhoeae, Streptococcus pyogenes and adenoviruses, some of these are highly contagious. I asked whether anyone else in the household developed pink eyes, and he said no. He had no systemic symptoms or swollen lymph nodes, which were a good sign. Pseudomembranes can also be caused by toxic and allergic agents, and even foreign bodies [reference 1]. So at this point I was still going with allergic conjunctivitis, but these other infectious causes were now on the back of my mind, making me uneasy. So I stopped the steroid drops and switched to an antibiotic/steroid combo drop, as well as adding an antibiotic ointment at night. Of course, the pseudomembrane had to be removed otherwise he would not get better.
1 week later he came back, this time he’s much better, no discomfort, not much discharge, no swelling or redness. Exam revealed residual tiny papillae, and the membranes were gone!
To summarize, pseudomembranes can be caused by infections, toxins, foreign bodies or allergies, and to treat it the underlying cause needs to be addressed, and pseudomembranes need to be removed promptly.
 Ho D, Lim S, Kim Teck Y. Pseudomembranous Conjunctivitis: A Possible Conjunctival Foreign Body Aetiology. Cureus. 2020;12(5):e8176. Published 2020 May 18. doi:10.7759/cureus.8176