head tossing at low sunlight?

[noblesteed]

Bit worried about my 17 yo gelding.
When we are hacking out in low sun (mainly winter) and we are passing hedges he often violently shakes his head to the right. It's when the sun is shining from the left. It only happens when sun is bright and low and you can see sunlight dapples through the hedges. It's as if the sun is getting in his eye and dazzling him! It's annoying but is it anything I should worry about? Given his age I am now panicking about cataracts etc! He certainly seems to be doing it more lately but it has been a relatively sunny winter here.

 

[SEL]

Its a pretty quick vet check for cataracts - my friend has her OAP mare checked annually alongside her jabs to see if they are progressing. She doesn't react so much to sunlight as to throw enormous spooks if something happens on her blind side.

My horse with nightblindness doesn't like extremes of dark and light though. Our indoor school has slats and we can get stripes on the ground when the sun shines through on bright days - hates those. I'm not sure whether she sees big black holes in the shadows, but she tends to treat them like a ditch with a troll in it.