Cataracts are the biggest cause of blindness in India
Cataracts account for 63% of the total number of cases of blindness in India.
India has the highest numbers of blind and vision impaired people in the world. The All India Institute of Medical Sciences in Delhi is conducting the country's first large-scale community-based study in Delhi where 20,000 children will be screened.
Once the results are out, the study will also be carried out in other parts of India.
Nearly 80 to 90% of blindness is avoidable and more than 90% of it is seen in people above the age of 50, say experts.
Most patients are unaware of what damages their vision. Consuming tobacco, betel nut and lime is also bad for the eyes, but most people are unaware.
Nearly 20% of children are also blind due to the use of steroids.
The survey will also look at the impact of vision-threatening diabetic retinopathy.