Possible to assign extra "data" to a chart point in highcharts?

Question

I know I can retrieve this.x and this.y from a data point, but is it possible to have set things up in such a way that I can also get this.myVar?

I've put it in the data array that I pass in:

[
    {x: 953337600000, y: 17, myVar: 1217},
    {x: 955152000000, y: 9,  myVar: 1305}
]

Etc, and that renders as expected, the same as if myVar wasn't there.

But I can't access this.myVar later in the JS.

I tried accessing this.point.myVar and am told that this.point is undefined?

Is there something trivial I can do to achieve this goal?

Thanks