 The disease causes an angle in the anterior chamber of the eye to be left open, which in turn causes the intraocular pressure to be increased.Although an increase in the intraocular pressure is a major factor for glaucoma, the disease can occur independently of the intraocular pressure.Furthermore, the damage done to the optical nerve has been classified as irreversible because no symptoms of the disease are apparent (asymptomatic) until its last stages.