The Sydney Harbour Bridge glaucoma test

If you are lucky enough to find yourself in Sydney at some point, and you haven't quite closed your mind to all things optometric, try this simple glaucoma test.

After coming out of the Opera House, gaze across at the Harbour Bridge. Close your left eye and fixate on the left hand pillar. You will notice that the right hand pillar disappears from view. Similarly, close the right eye (and open the left) and the left pillar will disappear when looking at the right one.

You will then notice that the arc of the bridge falls neatly across the inferior retinal arcuate fibres (the image being inverted on the fundus).