Many of the studies showing a improvement in symptoms after using Tea Tree Oil did not use controls. And one of the manufactures of a Tea Tree Oil produce sponsored many of the studies “proving” improvement after treatment. Thus many dermatologists and eyeMDs are still a bit sceptical about its benefit.
Some patients report significant improvements. Some report a great deal of burning, itching, irritation: some wonder if this is an allergic reaction to the TTO or the demodex dying. We don’t know for sure which one yet, but each patient will need to see how they react to TTO treatments especially if nothing else is helping (lid hygiene, baby shampoo scrubs, antibiotic ointment, cyclosporine).
Here is the best study so far with controls and not sponsored by a TTO manufacturer as far as I can tell. Below are more references but most did not use controls or were sponsored by a TTO manufacturer or where not the best studies and are published in less respected journals.