An Auckland woman says she owes her life to an eye test, after it led to a potentially fatal tumour in the lining of the brain being removed.
Marie Stringer, 54, of Mt Albert, says she was having occasional headaches and slight loss of peripheral vision, but nothing that seemed serious.
The mother of three had joined the Automobile Association and her partner urged her to have the free eye test offered to AA members by the Specsavers chain.
Jenny Kung, the optometrist who tested Ms Stringer's eyes last October, said she noticed abnormalities of the retina from images taken with a digital retinal camera.
The optic nerve was swollen, possibly an indication of increased pressure in the brain.
Ms Stringer was urgently referred to the eye clinic at the Greenlane Clinical Centre and then Auckland City Hospital, where a meningioma was diagnosed.
It was a benign - non-spreading - tumour, Ms Stringer said, but she was told the pressure the golf ball-sized mass was exerting on her brain would have caused serious problems.
Surgery in November removed virtually all of the tumour and an affected section of a vein had to be replaced with a piece of vein transplanted from one of her lower legs.
Two remaining parts of the tumour could not be safely removed. There is a risk they will gradually regrow and Ms Stringer is being checked every six months.
"According to the brain surgeon at Auckland Hospital, my sight would have been gone in two months and I would have lost my life in four.
"I feel very lucky to be alive."
Ms Stringer said her friends and family had been "lining up" to have their eyes tested.
Ms Kung said it was not the first time she had found abnormalities in eye tests that had led to a tumour being detected.
"It's happened a couple of times before in the last four years."
Professor Helen Danesh-Meyer, an Auckland University expert in neuro-ophthalmology, said Ms Stringer's experience was "very classic and is certainly not rare".
"Fortunately, brain tumours are relatively rare so most people who go for eye tests will not have tumours but certainly formal visual testing can identify both ocular and neurological abnormalities if they encroach upon the visual pathway.
"Neurological problems certainly may manifest in the eye, with a wide range of diseases ranging from brain tumours - perhaps the most scary - to other processes such as multiple sclerosis. One reason for this is that at least 40 to 60 per cent of the brain - if not more - is dedicated to visual processing, whether it is seeing or interpreting the world we see.
"In addition, the visual pathway extends from the back of the eyeball to the back of the brain so that the visual pathways are the longest and most extensive in the brain. So lesions anywhere can produce deficits in visual function.
"The importance of visual testing is that many deficits in vision go unnoticed by the patients without specific testing so patients can present almost legally blind with huge blind spots without being aware of them," Professor Danesh-Meyer said.