Who has poor vision wears glasses and us leader of the group in book Holes by Louis Sachar?

In the book "Holes" by Louis Sachar, the character who has poor vision and wears glasses is Dr. Pendanski. He is the counselor at Camp Green Lake and plays a leadership role among the boys. Despite his position, he often comes off as condescending and is not well-liked by the campers. His character adds complexity to the dynamics at the camp and highlights themes of authority and manipulation.