More than 1 million New Zealanders could be at risk of going blind.
Macular degeneration is the leading cause of blindness, but experts say early detection can save people's sight.
Auckland businessman Ross Legh has 20/20 vision. But last year, it was a different story.
"I thought that at one point I was going to go blind."
Last August he was looking out the window at a building opposite when he noticed the window frames looked distorted.
"In my left eye the window mullions weren't straight lines; they were wavy lines."
He knew of macular degeneration and got tested straight away. It saved his sight.
One in seven New Zealanders over the age of 50 will get macular degeneration, but a poll shows 40 percent of Kiwis don't even know what it is.
People with macular degeneration lose all of their central vision. They can no longer recognise faces, read, drive or, in most cases, work. With the condition, 20/20 vision can deteriorate in just weeks or months.
Eye specialist from Macular Degeneration New Zealand Dr Dianne Sharp fears people are going needlessly blind.
"People are going blind because once this has developed and the blood vessels have formed and the scarring has formed then we can't reverse that."
But it's easily detected. You can cover one eye and look at the dot in the centre of a grid, then repeat with your other eye. If the lines look distorted you need to get checked.
And there are now treatments that can save sight if it's caught early.
It might sound eye watering, but it's painless, and it can prevent thousands of Kiwis needlessly losing their sight.