One in every 200 people worldwide lives with blindness.
That’s 43 million individuals facing total vision loss—alongside another 295 million with moderate-to-severe visual impairment. In the U.S. alone, 6 million people live with vision loss, and over 1 million are blind. Perhaps most alarming: more than 1.6 million of those affected in America are under the age of 40.
Something of major concern is that vision loss is predicted to increase globally by as much as 55 percent in the next 30 years.
As the global population grows, so does the challenge of managing age-related health issues. By 2050, the world’s population is expected to reach nearly 10 billion, putting even more pressure on healthcare systems. One major concern is the aging population: today, about 1 in 11 people are over 65, but by mid-century, it will be closer to 1 in 6. With age comes a higher risk of vision problems, including cataracts, macular degeneration, and glaucoma. In fact, the number of people over 80 is projected to triple by 2050, making vision loss an even more urgent public health issue.
ISSUE WITH VISION LOSS
While vision impairments may seem natural with age, having such a large number of the population experiencing them causes worldwide problems. Individuals with vision impairment or blindness often experience restrictions in their daily lives: independence, mobility, and educational achievement, as well as an increased risk of falls, fractures, and injuries.
The impact of vision loss extends far beyond physical health. Vision impairment is strongly linked to poor mental health outcomes, including higher rates of depression and anxiety. Individuals with vision loss are also at greater risk for cognitive decline, as decreased sensory input can accelerate memory loss and impair executive functioning. Perhaps most damaging is the sense of social isolation that often follows, as those with vision impairment may withdraw from social activities, leading to loneliness and further mental deterioration. These effects are just as serious as the physical limitations of vision loss, and addressing them is critical to improving overall quality of life for an aging global population.
According to the International Agency for the Prevention of Blindness (IAPB), the two main drivers of increased vision loss are an aging population and lifestyle changes. The prevalence of vision loss and eye conditions—such as cataracts, age-related macular degeneration, and glaucoma—increases significantly with age. The IAPB cites factors such as “more sedentary and indoor lifestyles, less nutritious foods, and resulting obesity” as contributors to a surge in the prevalence of myopia and diabetes.
In order to see the whole picture, we need to understand how humans see and what leads to visual impairment. When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. The brain then turns these signals into the images we see.
Thus, humans face vision loss when their photoreceptor cells fail to regenerate due to damage from disease or other factors. The retina is a complex sensor that is involved in vision. In fact, this specific neuronal tissue in the back of our eyes is an external brain structure. Photoreceptor cells use this area to absorb light and transform it into electrical messages, which eventually shape our vision. These photoreceptors are not repaired in humans if they become nonfunctional due to disease or other factors. They cannot be restored once gone, which results in permanent vision loss.
A POTENTIAL SOLUTION
Recently, a team of researchers led by Michael Brand, PhD, at the Center for Regenerative Therapies Dresden (CRTD) of Dresden University of Technology has made headlines in this area with their novel approach.
Brand’s team revolved their study around the zebrafish, an animal naturally capable of photoreceptor regeneration. The researchers demonstrated that regenerated photoreceptors are as good as original ones and regain their normal function, allowing the fish to recover complete vision. Their results, published in the journal Developmental Cell, offer insights for the future of photoreceptor replacement therapies, which could lead to groundbreaking treatments for vision loss due to the possibility of regenerating or replacing damaged photoreceptors in humans, offering hope for individuals with retinal diseases and paving the way for advancements in therapies that could restore vision.
Annie Free, an MSc student in Genetic Counseling, stated that Brand’s research impacts how we perceive gene editing related to vision. “I’m most excited about CRISPR gene editing for individuals with inherited vision loss. Last year, Mass General published findings from a trial they conducted with 14 participants with inherited blindness, eleven of whom showed improvement after treatment with CRISPR gene editing. Although it’s still early in the course of research, the results are promising, and this kind of therapy could greatly benefit individuals who suffer from inherited blindness,” said Free.
“However, our cells have lost the ability to regenerate during evolution. Since these cells are so very similar, however, it may be possible to rekindle this regeneration potential for therapeutic applications in the future,” Brand said. “However, it is crucial to determine if such new photoreceptor cells can function as effectively as the originals.”
It has long been known by researchers that zebrafish can regenerate damaged retinas, with new photoreceptors appearing identical to the originals. Various groups, including Brand’s group, came up with behavioral tests that confirmed that fish regained vision after regeneration. But these tests could not directly assess the extent to which the photoreceptor function was restored.
ETHICS
Is the use of vision restoration technologies such as CRISPR gene editing, stem cell therapies, and retinal transplants ethical?
While advancements in vision restoration provide hope, they raise complex ethical questions. Gene-editing technologies like CRISPR have the potential to correct inherited blindness, but they also spark concerns about unintended genetic consequences and accessibility. Who will have access to these treatments, and will they be affordable, or will they only benefit the wealthy?
Additionally, stem cell therapies and retinal transplants involve delicate ethical considerations, particularly regarding the source of stem cells and the long-term effects of altering human biology.
Free said, “Any form of research, especially when involving human subjects, raises significant ethical concerns,” emphasizing the importance of careful oversight. She continues, “When research includes human subjects, it is of utmost importance to follow established ethical guidelines, such as those included in the Belmont Report. This report highlights three key principles: respect for persons, beneficence, and justice.” Free stresses that “these principles should always be in the back of a researcher’s mind, as certain participants in such studies may be in vulnerable positions and require special consideration.”
This reminder is crucial, particularly in fields where participants may not fully grasp the implications of the research. There is also the question of informed consent—how much do patients truly understand about the risks of these experimental treatments? Ensuring clarity and transparency is just as important as adhering to ethical guidelines.
If scientists eventually succeed in enhancing human vision beyond natural capabilities, it could create a divide between those with access to superior sight and those without.
As research progresses, these ethical concerns must be addressed alongside scientific breakthroughs to ensure that treatments are safe, equitable, and aligned with societal values.
While advancements in vision restoration provide hope, they raise complex ethical questions. Gene-editing technologies like CRISPR have the potential to correct inherited blindness, but they also spark concerns about unintended genetic consequences and accessibility. Who will have access to these treatments, and will they be affordable, or will they only benefit the wealthy?