Tapetum Lucidum

As it's my last day trialling the Volk Pictor handheld fundus camera I thought I'd have some fun and see if I could show you the inside of a dog's eye.

Archie was surprisingly accommodating as he's very easy to bribe with a biscuit!

Many animals, including dogs and cats, have highly reflective eyes which produce a yellow-green reflex, rather than the red-reflex we see in humans when a flash is used. I've demonstrated by inserting a piccie of Archie, taken with my G9 on auto setting this evening.

Tapetum lucidum literally means 'bright tapestry'. It's the layer of tissue which lies immediately behind or actually within the retina. its purpose is to reflect visible light back through the retina, so increasing the light available to the photoreceptors and improving vision in low light conditions. One externally visible effect of this is 'eyeshine' when a bright light is shone into the eyes. This was apparently the inspiration behind the cats eyes we see along the centre of roads :-)

Humans don't have this tapetum lucidum and as a result we have much poorer night vision than our less highly evolved fellow vertebrates.

I hope you've enjoyed this, admittedly self-indulgent, meander through a little bit of my world.

Normal service will be resumed tomorrow.