Since I had surgery a couple of years ago, my eye has become one of the main ways I can recognise I’m not at my best.

I have noticed a black spot appears in my field of view when I’m especially fatigued. It sits in my vision and moves every time I try and focus on it. It’s a true ‘dead spot’ in my vision; it’s literally (the correct usage) where there is a part of my retina that can’t pick any images up.

How many black spots do you have, always there, never normally noticeable, but suddenly in the way when you’re under pressure?