Recent estimates suggest that nearly 45 million people worldwide fulfil the World Health Organization's criterion for blindness, defined as a best corrected vision of less than 3/60 in the better seeing eye.1 An additional 135 million people are visually disabled and in need of social, vocational, economic, or rehabilitative support services. To compound matters, more than 90% of all blind and visually disabled people live in the developing world, where common causes of bilateral vision loss include cataract, glaucoma, trachoma, vitamin A deficiency, and onchocerciasis. Additional causes of bilateral vision loss, which together comprise nearly one quarter of all blindness and which affect people in both developed and developing nations, include diabetic retinopathy and macular degeneration, …