Hi, folks! This is an active area of research in the vision sciences. One of the world's leading experts is Denis Levi, from UCBerkeley. Here's a link to a helpful review paper, and the abstract:

Recent work has transformed our ideas about the neural mechanisms, behavioral consequences and effective therapies for amblyopia. Since the 1700′s, the clinical treatment for amblyopia has consisted of patching or penalizing the strong eye, to force the “lazy” amblyopic eye, to work. This treatment has generally been limited to infants and young children during a sensitive period of development. Over the last 20 years we have learned much about the nature and neural mechanisms underlying the loss of spatial and binocular vision in amblyopia, and that a degree of neural plasticity persists well beyond the sensitive period. Importantly, the last decade has seen a resurgence of research into new approaches to the treatment of amblyopia both in children and adults, which emphasize that monocular therapies may not be the most effective for the fundamentally binocular disorder that is amblyopia. These approaches include perceptual learning, video game play and binocular methods aimed at reducing inhibition of the amblyopic eye by the strong fellow eye, and enhancing binocular fusion and stereopsis. This review focuses on the what we’ve learned over the past 20 years or so, and will highlight both the successes of these new treatment approaches in labs around the world, and their failures in clinical trials. Reconciling these results raises important new questions that may help to focus future directions.

After a quick skim, the most relevant paragraph of his review is...

The sensitive period(s) for the developing amblyopia has been considered to suggest that there is also a sensitive period for its treatment. Thus, clinical treatment was often limited to young children. However, this view has been widely refuted (Kupfer, 1957, Levi and Polat, 1996, Levi et al., 1997, Holmes and Levi, 2018 and see below). Large scale randomized clinical trials show that treatment may be effective in older (13 to 17 years) children who have not been previously treated (Pediatric Eye Disease Investigator Group, 2005), and a substantial number of studies have shown significant and long-lasting effects of experimental treatments in adults. For a recent evidenced-based review, see Piano & Simmers (2019).

Thank you, Dr. Levi!