At the time, the Northland Regional Council employee had been driving to Whangarei to act as the key witness in an Environment Court hearing.
Mr Nager said it was the most terrifying experience of his life.
"To be honest I thought I was going to die. With the knife and everything, I thought, `this is it'.''
Thick fog blanketed State Highway 10 that morning so it took as long as half an hour before a passerby noticed him in the layby beside Oromahoe Rd. The woman called 111 and found Mr Nager's first aid kit, doing her best to wash his eyes.
He was taken to Bay of Islands Hospital in Kawakawa where his eyes were irrigated with saline.
At first he could only make out shapes and didn't know if he would see again. His vision returned a week later but he now has to wear reading glasses.
Worse, however, are the emotional effects and knowing his assailants are still on the loose.
He was back at work within 10 days and coping well until he was reassigned the council ute he was driving at the time of the attack. The flashbacks became so vivid he could feel the stinging of the bleach and the blade across his face.
Eventually he was unable to continue. He has been on ACC since October. Mr Nager said he had been working towards a return to his role as an environmental monitoring officer, a job he loved, but was now looking for a new career.
He could now drive through Oromahoe without feeling fearful but had yet to fully confront his memories of the attack by returning to the layby. That was still on his "to-do'' list, he said.
In the meantime he hoped his attackers would be found.
"I appeal to anyone who knows something, or has heard someone talk about it, to come forward ... It's had such a horrible effect on me and my family's life. I was just doing my job.''
Police believe at least two people were involved in the attack. The only description they have of their vehicle is that it was white or silver with a sloping bonnet, similar to a Honda Accord or Prelude. Mr Nager's wallet was recovered at the scene but not his cellphone.
Call Kerikeri police on (09) 407 9211 with any information or Crimestoppers, anonymously, on 0800 555 111.