That is the tradition.

I tooke a bodkin gh & put it betwixt my eye & the bone as neare to the Backside of my eye as I could: & pressing my eye with the end of it (soe as to make the curvature a, bcdef in my eye) there appeared severall white darke & coloured circles

https://www.newtonproject.ox.ac.uk/view/texts/normalized/NAT...