Thank you for your query. It is always upsetting to see our pets ‘out of sorts’. Dogs can develop conditions that will affect their eyesight and ageing can definitely be a contributing factor. It may be worth revisiting your vet if the problem hasn’t improved since you first went. Sometimes it might helpful for the vet to see a short video of your dogs behaviour to demonstrate how he is acting at home. If you have a smartphone I would advise this as the video may offer some insight to your veterinarian as to what is going on. Like humans, as dogs get older they can start to show senile behaviour, so the video would also help determine whether your little dog is showing any signs that would represent this. A full clinical exam performed by your veterinarian, including an ophthalmic exam should provide some clues to what is going on and then an appropriate plan can be put into place.
I hope you manage to get him back to his normal self very soon.