With promising early results, the researchers say their findings could usher in trials where such transplantations are put to the test in humans. 

Stem cells have shown exciting potential in improving the vision of patients with degenerative eye disorders for years. In 2010, scientists reported the creation of the first early-stage retina engineered with human embryonic stem cells. Then in 2012, two legally blind patients experienced improvements to their vision after receiving transplants of retinal cells, also derived from human embryonic stem cells. 

But what sets this latest achievement apart is that scientists from Osaka and Cardiff University's were able to use human stem cells to reproduce something closer to the complex nature of the entire eyeball. Using induced pluripotent stem cells, or cells derived directly from adult cells, they were able to cultivate multiple cell lineages of the eye, including the lens, cornea and conjunctiva.