Hi, I can help you with your question today.
We can see some situations where an animals sight may come and go.
The most common reason for this would be hypertension.
Our best chance at maintaining his sight is to have him evaluated by a vet right away.
I would start with a physical, ocular exam and blood pressure measurement.
If we confirm hypertension, we should start him on a medication called amlodipine right away.
The sooner we can bring his blood pressure to normal,. the better chance we will have of saving his vision.
If you have more questions or if I can help in any other way, please do not hesitate to ask. I will be happy to continue further and do everything I can to provide you with the service you seek.