Lab Grown “Mini Brains” Develop Functioning Eyes

By Natalia Pepe, 2028

Published 9/28/2025

In a world where the human brain remains one of science's most elusive mysteries, lab grown brain organoids have been astonishingly discovered to develop rudimentary but functioning eye-like structures. This breakthrough offers not only hope for treatment of numerous neurological conditions, but also gives rise to necessary questions regarding the progression of scientific research and whether ethical regulations surrounding such incredible breakthroughs can keep up. 

A brain organoid is a tiny, artificially constructed tissue developed from stem cells, designed to emulate a human brain. The development of brain organoids mirrors embryonic development, providing scientists with a valuable model of neurological disorders and their development in the womb. Through a 2021 German study, researchers used brain organoids to investigate the development of retinal disorders before birth. The process began by transforming stem cells into neuroectoderm, which, in embryos, becomes the brain and eyes. By the 30th day of organoid development, they began to display pigmented spots resembling early eye structures known as optic vesicles, containing early retinal layers. As the organoids grew, however, something fascinating happened—not only retinal, but corneal and nerve cells began to connect brain regions, pointing towards early signs of functional eyes. Sure enough, when the researchers tested the organoids’ response to light, 72% of the organoids reacted to the light using human-like photoreceptors, indicating the true functionality of the eyes. 

Although this breakthrough was remarkable to the scientific community, moral and ethical dilemmas quickly arose. As brain organoids become increasingly developed, many are concerned about whether the structure could also form thoughts, awareness, or sentience. Additionally, their reactivity to light suggests to some that brain organoids might quickly become capable of feeling pain. Additionally, due to the relatively recent introduction of such advanced brain organoids to research, regulations surrounding them are not clearly defined. This has led many to argue that stem cell donors should be notified of whether their cells are used to create organoids, especially those with such complex features. 

Alternatively, others argue that more complex brain organoids are intensely valuable to the scientific community as a whole. In the future, doctors may use a person’s own cells to create personalized organoids and identify the optimal treatment for their disease. These lab-grown models also reduce the need for animal testing. In the case of this experiment specifically, however, these discoveries could lead to new therapies that fix or prevent blindness and other brain-related disorders, giving hope to many people affected by these conditions.