Dermodex mites are actually totally normal! They're a common, naturally-occurring commensal skin parasite that live, feed, poop, and die on your skin and on eyelashes and eyebrow hairs, and most of us have them. I know, I know, it sounds gross, but it usually doesn't cause any issues... Unless these mites overgrow. Then their presence can lead to things like blepharitis - or eyelid information. No fun. How can you determine if these mites are a cause of your eye rash? There are a couple of ways:

Eyelash Mites: Millions of People Have Them and Don't Know (Symptoms)