According to the Catholic Church, what did Jesus mean by saying "Neither this man nor his parents sinned"? John 9:3 (NIV)


  "Neither this man nor his parents sinned," said Jesus, "but this happened so that the works of God might be displayed in him.


Here you have the clear understanding That sin brings on sickness ,but Jesus seems to have another explanation here (or in this situation).

What is Jesus saying here according to the RCC?
The Catholic Haydock Commentary on this verse says:


  Ver. 3. When Christ says that neither he nor his parents had sinned, we must not understand that he was born without original sin, nor even that he had not committed other sins. For both he and his parents had sinned; but the meaning is, that this blindness was not a penal blindness inflicted in punishment of any sin either himself or his parents had committed; but, as is afterwards subjoined, it was sent him for the manifestation of the glory of God. S. Austin, tract. xliv. in Joan.