Blindness (visual acuity of less than 360 in the better eye with available correction) is estimated to affect around 39 million people in the world out of which 19.9 million due to cataract. An additional 246 million have low vision (visual acuity of < 618 to ⩾360 in better eye with available correction) giving a total of 285 million people with visual impairment (visual acuity