A paranoid schizophrenic who repeatedly stabbed a mother and her son and sliced their eyelids has been sectioned in a high security mental health hospital.

Kumaran Kanesh, a student of veterinary sciences, attacked the family on August 21 last year at their home in Mitcham at about 10am.

While brandishing a 30cm kitchen knife, Kanesh, 37, bound the hands of the 39-year-old and her 10-year-old son and wrapped tape around their mouths.

He told the woman not to call the police or shout out or he would hurt the boy and repeatedly demanded she admit to the "bad things" she had done to him.

He then took the knife to the boy’s eyes, slicing his upper eyelids.

Panicking, the woman jumped in front of her son and, managing to free her hands, started to fight with the Sri Lankan national.

Eventually she was able to grapple the knife from the man and told her son to run.

He escaped screaming into the street where he was helped by a member of the public.

His mother also escaped but only after being stabbed 17 times in her upper and lower eyelids, left shoulder, forearms.

At one point Kanesh forced the knife right through her hand.

Arrested at the scene, he was found with a second smaller paring knife which he said was in case he lost the larger knife during a struggle.

He pleaded guilty to two counts of wounding with intent and two counts of false imprisonment at Kingston Crown Court on February 6 after admitting to police the attack was pre planned.#

Miraculously his victims recovered from the ordeal and have retained full vision however the boy is said to be suffering with flashbacks and post traumatic stress.

At Kingston Crown Court on Monday, the court was told how Kanesh’s mental health and paranoia had worsened since 2009 when he had spent time in a psychiatric hospital in Sri Lanka.

In court the veterinary student was described as an "intelligent man" whose actions were caused by his failure to take his medication and was harbouring a "massive sense of regret."

Roderick Jones, defending, said: "He has, it seems continued to balance what is undoubtedly a well ordered and intelligent mind, with this sense of disorder in respect of his emotional state."

Passing sentence at Kingston Crown Court on Monday, March 25, Judge Dodgson said: "On that day, because of your untreated illness, your mental illness overwhelmed you and you behaved in an extremely violent and deeply disturbing way.

"The attack seemed to me frenzied."

He added: "Cutting him to the eyes with a knife as you did was potentially devastating and it is perhaps a question of luck that he was able to escape as he did."

Should Kanesh have been found to be of sound mind Mr Judge Dodgson said the sentence would have been nearing "double digits".

But, because he accepted Kanesh had committed the crime while suffering from a mental illness, he sentenced him to detention at Broadmoor Hospital, a high-security psychiatric hospital in Berkshire.