I saw this news article:
Dark Therapy Shows Promise in Addressing Lazy Eye Condition
Then I did a quick search and found this study on kittens:
Recovery of visual functions in amblyopic animals following brief exposure to total darkness
Doesn’t seem very brief:
The parameters of darkness were strict because no visual recovery was observed after 5 days of darkness. In addition, short periods of light introduced each day during an otherwise 10 day period of darkness obliterated the benefits.
It could be nothing, and I didn’t look too much into it. I was hoping someone more knowledgeable than me could comment.
There are other studies as well.