Wentworth Miller has revealed he received an autism diagnosis a year ago, and he's sharing his feelings about it with the world.

The "Prison Break" star said on Instagram, "This isn't something I'd change ... immediately being autistic is central to who I am. To everything I've achieved/articulated."

He did not include a picture alongside the caption, and instead posted a blank white square. He continued: "This fall marks 1 year since I received my informal autism diagnosis. Preceded by a self-diagnosis. Followed by a formal diagnosis. It was a long, flawed process in need of updating. IMO. I'm a middle-aged man. Not a 5-year-old."

Wentworth is 49.

Miller wrote that he knows "access to a diagnosis is a privilege many do not enjoy," and that the diagnosis was "a shock" but "not a surprise."

"I don't know enough about autism. (There's a lot to know.)," he wrote. "Right now my work looks like evolving my understanding. Re-examining 5 decades of lived experience thru a new lens."

Meanwhile, he adds, "I don't want to run the risk of suddenly being a loud, ill-informed voice in the room. The #autistic community (this I do know) has historically been talked over. Spoken for. I don't wish to do additional harm. Only to raise my hand, say, 'I am here.' Have been (w/o realizing it)."

Miller thanked people in his life who "consciously or unconsciously gave me that extra bit of grace + space over the years" and allowed him to "move thru the world in a way that made sense to me whether or not it made sense to them."