Complex sentence: About 20 million people are blind due to cataracts, and it is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America.
Split into simpler sentences: About 20 million people are blind due to cataracts. It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America.