Close-up of a sore, inflamed eye in acute glaucoma, with an irregular enlarged pupil. Glaucoma describes an abnormally high intraocular pressure, the pressure within the eye. Primary glaucoma may arise in the absence of any other eye disease; secondary glaucoma is due to pre-existing eye disease disrupting the normal circulation of aqueous humour within the eye. Primary glaucoma occurs increasingly with age & is an important cause of blindness. Treatment is directed at reducing the intraocular pressure, by improving the outlfow of aqueous humour from the eye or supressing its production. This is done using drugs (diuretics) or by surgical methods.