An inquest is due to resume today into the deaths of an elderly couple at their home in Kendal.
It's thought 92 year old Stanley Wilson stabbed his 89 year old wife Peggy before taking his own life.
The inquest has heard from mental heallth professionals who said Mr Wilson had wrongly believed his wife was trying to poison him.
A 92 year old man who knifed his wife to death and then himself in Cumbria had acted "out of character" for weeks after an eye operation, an inquest has heard.
Stanley Wilson believed wife Peggie, 89, was trying to poison him and that other family members were in on the "plot".
Their bodies were found in the front bedroom of their home in Kendal on February 18 last year.
Former quarry worker Mr Wilson had started to lose his sight months before and had an operation for a detached retina at St Paul's Hospital in Liverpool after Christmas.
Relatives of the "devoted couple" and their neighbours told an inquest into their deaths that his behaviour drastically changed following surgery.
The pensioner believed his wife was attempting to alter his mind so that he would change his will and refused to eat any meals she served.
She suffered multiple injuries at their address in Mint Dale with numerous knife wounds to the neck - one which severed her jugular vein - and blunt trauma injuries to the face and head, consistent with punching. There were also signs that she had been asphyxiated.
Pathologist Dr Alison Armour told the Kendal hearing: "This frail old lady died as a result of a sustained and violent assault. She died from a combination of these injuries." She ruled that Mr Wilson died from self-inflicted knife wounds, with many again to the neck.
Giving evidence, Mrs Wilson's daughter, Sandra Smith, from Leeds, said that "out of the blue" her mother rang her in January last year to tell her of the poison accusations. "He would not let her make any meals or even make a cup of tea," she said. "It was totally out of character for him."
The inquest heard Mr Wilson had become depressed through his eyesight problems and being forced to stop driving but nothing noticeable until after the eye operation.
It led to concerns being raised with his GP and he was admitted to Royal Lancaster Infirmary for assessment but was discharged shortly before the tragedy