Sorry to hear about your father. I had a similar experience with my stroke and have a left homonymous hemianopia which is still with me 18 months on.
It is still early days in your father’s recovery so he may recover some of his visual field and maybe even fully recover.
I would suggest getting an appointment with ophthalmologist as soon as you can, this way he will be able to take a few tests, one called the Snellen test, which will give you a base line percentage score for his visual field loss. You should then follow this up with more Snellen tests over time e.g. 6-8 weeks’ post stroke and around 6 months which will give you an idea of any recovery made.
Contact people such as the RNIB who will be able to help your father with advice and even practical support. They pointed me in the direction of KAB (Kent associate for the blind) who couldn’t have done enough to help.
Although I was considered “young” to have a stroke at 27 and much of my recovery was helped hugely by this the lack of recovery in my sight really affected my way of life. I had to surrender my driving licence, couldn’t get to and from work, cannot go out in busy areas without sighted guidance or without my symbol cane. Throw in the neglect your dad has too and it is all a big change, I just hope that he can recover some of that sight.
Sorry to sounds all doom and gloom but it is a huge change for anyone. If I can help in way with more info or have any questions, please let me know.