Many ocular diseases can damagesandfunctionalloss， cause the visual system which lcad toblindnessand low vision．Thatwil1notonly affectpatients’daily life and working abilities， but also have an adverse consequence to the society and economy developm ent． Nowadays．the visualim pairm enthasalready become a public health problem worldwide The 晦，0rld Health Organization WHO estim ated that there were approximately 161 million visually impaired people all overthe world，and am ong them 37 million wereblind． Over 90％ blind people 1ived in developing countries． China has a 1arge population． and the blind and low vision problem can not be ignored． In 2006． China national survey on disability showed that there were 12330000 visually disabled people in China． which accounted for 14．86％ of overall disabilities． Understanding the prevalence and m ain causes of blindness and low vision and 1ooking for efective treatm entm ethodsisessentialfo rthepreventionofvisual impairment．