Eye eye

This is a close-up photo of my retina, taken by my optician as a benchmark for comparison as I grow older. This is a healthy retina. On the left is where the optic nerve exits my eyeball to my brain, the dark patch to the right is the macula, the section of the retina (with the fovea at the center) responsible for my detailed vision.

If the human eye were a camera it might have a resolution of around 80 megapixels, but it doesn’t really work like that – the only part of the eye that sees things in fine detail is the fovea. The fovea primarily consists of a high concentration of cone receptors, the kind of optical receptor that detects colours, but only work in relatively bright light. The rest of your eye has more rod receptors, which are great at detecting lower levels of light, but can’t manage colour.

This is why you can’t see faint stars if you look directly at them, and why they all look white when they’re actually all kinds of colours. What you see and what is actually there are not the same. The human body is pretty impressive really. Don’t even get me started on perception.

Apart from having my eyes inspected, I’ve now had booster jabs for hepatitis and other nasties, and had my teeth checked. 18 days to go.

Possibly related posts:

• Monday bullets
• Calorific
• Hard work
• Inside the Dog Chapel
• Tick tock