The death of an eight-year-old boy could have been prevented if an eye specialist had "done her job properly", a court has heard.
Vincent Barker, known as Vinnie, died on July 13 2012 - around five months after he was taken to have a routine eye test at Boots the Opticians in Upper Brook Street in Ipswich, Suffolk.
The conduct of locum optometrist Honey Rose, 35, fell so far below the standards expected that it was "criminal", prosecutor Jonathan Rees QC said.
Rose, from Newham, east London, is charged with gross negligence manslaughter.
Mr Rees told Ipswich Crown Court: "The prosecution allege that Vinnie's death was preventable and would have been prevented had the defendant, Ms Rose, done her job properly."
Jurors heard that post-mortem examinations showed the cause of death was hydrocephalus - a build-up of fluid in the brain which led to an increase in pressure within his skull and, ultimately, his collapse and death.
They were told that Rose owed a duty of care to her patients and this included a duty to carry out a competent examination of the eye and a duty to make an urgent referral if any injury or disease was detected.
Mr Rees said: "At the heart of the prosecution case against the defendant is the allegation that the defendant's failure to detect the swollen optic discs and refer Vinnie on for further investigation was grossly negligent - key phrase in this case - on her part."
He added: "Given the risk of death involved, her conduct was so bad in all of the circumstances - it fell so far below the standards to be expected of a competent optometrist - that it was criminal."
Mr Rees said it is agreed that, at the time of Vinnie's examination on February 15 2012, there were "obvious abnormalities" in both of his eyes.
The jury heard that photographs taken by another member of staff of the back of his eyes shortly before he was examined by Ms Rose suggested he had bilateral papilloedema - the optic disc at the back of each eye was swollen because of the raised pressure within his skull.
Mr Rees told the court: "The prosecution say that the abnormalities in his optic discs would have been obvious to any competent optometrist who had examined them."
He said this would have led to him being "urgently referred for further investigation" because of swollen optic discs signifying that the patient may be suffering from papilloedema, "which is known to be a life-threatening condition".