As a major cause of blindness and visual morbidity, glaucoma is an important public health issue. The number of people worldwide aged between 40 and 80 years who have glaucoma is predicted to increase from 64.3 million in 2013 to 111.8 million in 2040 (Tham et al. 2014). In 2010, it was estimated that, worldwide, the number of people bilaterally blind as a result of glaucoma was approximately 8.4 million and is likely to increase to 11.2 million by 2020 (Quigley and Broman 2006). Approximately half of these cases are due to angle closure glaucoma, which predominantly affects those of Asian ethnicity