Acute primary closed angle glaucoma is fast becoming one of the most important causes of blindness in the 21 st Century. World bhnding statistics show that there are 60 million people suffering from glaucoma. Of these,approximately 6 million are blind and 1.5 million (25%) are due to acute closed angle glaucoma. With the aging population, the number of patients blind from glaucoma will continue to increase.Attacks from acute primary closed angle glaucoma can lead to irreversible blindness to the affected eye.Blindness can be effectively prevented in acute primary closed angle glaucoma because the severity of symptoms will draw the attention of the patient who will then seek for medical care. Therefore, it is essential to educate the public,doctors and healthcare workers about the danger and symptoms of acute glaucoma. With early diagnosis and treatment to the affected eye and laser iridotomy to the fellow eye-bilateral blindness from acute glaucoma can be prevented.This paper highlights important clinical advances in the management of acute primary closed angle glaucoma and also poses several questions for discussion.(1) What evidence is there to suggest that bilateral blindness from acute primary closed angle glaucom is preventable?(2) In what way is Ultrasonic Biomicroscopy (UBM) useful in clinical research in glaucoma?(3) Will UBM be important in clinical diagnosis in primary closed angle glaucoma?(4) What is the scientific basis of treatment in acute primary closed angle glaucoma?(5) What are the essential procedures to preserve vision in chronic primary closed angle glaucoma?(6) What are the reasons for blindness after laser iridotomy?(7) What is the mechanism of laser iridoplasty?(8) What are the reasons why laser iridoplasty should be combined with laser iridotomy?(9) Why there is an intraocular pressure increase in 50% of eyes within 3 months after laser iridoplasty?(10) Can UBM explain the changes in the angle after lens removal in primary closed angle glaucoma?(11) Are there reasons why trabeculectomy is infrequently used in acute glaucoma, yet it is an important procedure in chronic primary closed angle glaucoma?(12) The scientific reasons why laser iridotomy is essential in the fellow eye.