National RAAB; Sample size: 4047; Reference: Lepcha NT1, Chettri CK, Getshen K, Rai BB, Ramaswamy SB, Saibaba S, Nirmalan PK, Demarchis EH, Tabin G, Morley M, Morley K. Rapid assessment of avoidable blindness in Bhutan. Ophthalmic Epidemiol. 2013 Aug;20(4):212-9. doi: 10.3109/09286586.2013.794902. Epub 2013 Jul 10.