it has now been found that tetrahydrocortisol alone , when in solution or in the form of nanoparticles , or a combination of compounds where each affects intraocular pressure by a different mechanism of action is especially valuable for the treatment of elevated intraocular pressure and glaucoma , especially in the resistant patient . with such a combination , each compound may be present at a reduced concentration , even to a sub - therapeutic level , thus decreasing or eliminating troublesome side effects while the combined effect on reducing intraocular pressure remains in the therapeutically useful range .