Simplify the following text for a Grade 9 native English-speaking person.
Original: Though legally blind because of astigmatism and a subsequent injury to his right eye , Knight pursued his artistic talents with the help of specially-designed glasses , and at the age of twelve , he enrolled at the Metropolitan Art School to become a commercial artist .
Simplified: He had severe astigmatism , and a later injury to his right eye , but had specially-designed glasses . At twelve , he enrolled at the Metropolitan Art School to become a commercial artist .