What is Misopt and what is it used for? Misopt lowers high pressure in the eye, a problem typically caused by the condition known as open-angle glaucoma. Misopt works by reducing production of the liquid that fills the eyeball. Most important fact about Misopt. Although it often causes no symptoms at first, high pressure in the eye will eventually damage the optic nerve and lead to blindness. It's therefore very important to keep using this prescription even if your eyes seem okay.