A retired nurse had been insulted for being straight in a gay bar when she threw a glass that struck another woman on the head, knocking her out.
Paula Flood (50) had been antagonised by a gay man in the well-known Dublin bar when she "lashed out" and threw the glass, missing him but hitting the woman who was an "unintended target".
Adjourning the case, Judge Michael Walsh said it was a "nasty, unprovoked attack" and told Flood to take part in a restorative justice programme.
He said more information on the victim's medical expenses was needed before compensation could be measured.
Flood, of Whitechurch Drive, Rathfarnham, admitted assault causing harm to the woman and producing a glass as a weapon in the course of a dispute.
Dublin District Court heard that the incident happened in the George Bar, on South Great George's Street, on February 7, 2015. A garda said the victim was socialising in the pub.
Separately, Flood got into an altercation with a man, who walked away from her.
Flood threw a glass in his direction and missed him, instead hitting the victim on the back of the head.
The woman fell to the ground and lost consciousness for a few moments.
She was taken to St James's Hospital but had no obvious cuts to her head and was given painkillers.
However, in a victim impact statement she said she suffered concussion for six to eight weeks after.
She had headaches, had difficulty concentrating at work and became forgetful. She suffered a milder form of concussion for months, the court heard.
What happened frightened the woman and when she eventually returned to the George Bar she began crying and had to leave. She had to cut down on social events as a result.
She hated having people behind her and would now sit with her back to the wall.
"Flood was antagonised by another individual for being a straight individual in a gay bar," defence solicitor Michael French said.
The man insulted her, she was "relatively intoxicated" at the time and lashed out. Flood was very remorseful.
She had worked as a nurse but suffered from severe anxiety and had retired.