Ward underwent surgery on serious facial injuries after being struck with a ball during the Olympic qualifier with Malaysia in November.
The 28-year-old, who scored twice as GB won the tie, is still hopeful of making the squad for Tokyo 2020 – although the damage to his retina will only become clear over the coming months.
"Over the last week, I have received advice from three separate eye consultants," said Ward. "They have all told me that I have suffered damage to the retina of my left eye and that this damage is partly irreversible.
"I may get some sight back, but this won’t be a quick process, and whether it will be sufficient for me to get back to playing international hockey only time will tell. It is a tough pill to swallow but, as people know, I am not one to give up easily and I will do everything can to make myself available for selection for Tokyo."
Mark Hager’s men’s side secured a 5-1 aggregate win over Malaysia in London to qualify for next summer’s Games, while the women earned a title defence shot by beating Chile in their play-off.
Ed Barney, GB and England Hockey’s performance director, added: "Sam has suffered a very serious injury. At present, our focus is on supporting Sam to the best possible extent and ensuring that he has access to the best medical provision and wider support."