What is the ruling on leaving a small amount of solidified rheum at the base of the eyelashes that is difficult to remove except by rubbing, knowing that rubbing worsens the condition?

The rheum must be removed because it constitutes a barrier. However, a small amount of rheum, or what is difficult or harmful to remove, does not impede [the ablution]. Therefore, strive to remove what you can, and what remains of the small amount or what is difficult to remove is excused.