A 42-year-old man, who had almost non-existent peripheral vision, will be sentenced next Friday for dangerous driving causing the death of a 70-year-old woman.
David Byrne, of Sunnyhill, Castlemartin Lodge, Kilcullen, Co Kildare, was suffering from a medical condition affecting his eyesight.
The prosecution said he should not have been driving.
Patricia Dunne was hit by a car being driven by Byrne as she crossed Collins Avenue East in Dublin on 16 October 2015.
She was thrown in the air and later died from her injuries.
Her son told Dublin Circuit Criminal Court that her sudden loss had caused the family untold stress and grief.
They believed her death was a factor in their father's death.
The couple had been married for 52 years and were "inseparable", he said.
John Dunne said the family had suffered relentless pain every day since their mother's death.
He said Byrne had shown no remorse and offered no apology and his not guilty plea had put them through two weeks of hell.
He said they would never forgive him for killing their mother.
The court heard Byrne was married with two children and had no previous convictions.
His senior counsel Michael O'Higgins said he wanted to offer the fullest possible apology to the Dunne family.
The court heard he was overcome and crushed with remorse for his actions.
Mr O'Higgins asked the court for the maximum leniency possible.
Byrne was suffering from a medical condition known as Usher Syndrome Type 2, which results in difficulty seeing in low light and also affects peripheral vision.
The trial heard that Byrne had been told in 1997 that he should not be driving.
An optometrist who gave evidence to the trial said Byrne's peripheral vision was almost non-existent.
He said he noticed Byrne using his sense of touch to enter a room when he attended an appointment at Specsavers in 2012.
Judge Patricia Ryan said she wanted to consider the submissions and the testimonials handed in on behalf of Byrne and would sentence him next Friday.
Byrne will also be sentenced next week for failing to declare his condition when he obtained a driving licence and car insurance.