Restoring Eyesight to the Blind? Not a Thing of the Future!
Think the possility of restoring eyesight to the blind is a thing of the future? Think again. Researchers from the University of Montreal in Canada and University of Trento in Italy have revealed the reorganization the brain goes through to compensate for lost vision can be reversed. The idea of the possibility of being able to restore a person’s eyesight is particularly exciting, especially for those people who have lost their eyesight throughout their life.
There is no doubt that the mind is extremely powerful. The brain has an amazing capability of creating new neural connections in response to injury or changes in the environment. This adaptation is referred to as neuroplasticity, or the capacity of the brain to change as a result of experience.
Neuroscientists have previously thought of the brain as a static organ that does not respond well to change. Recent studies by a team of researchers from the University of Montreal and the University of Trento in Canada and Italy respectively, has shown that this is not always the case.
Critical Periods in Vision
Previously, scientists have agreed that there are critical periods during childhood where any kinds of deficiencies can be corrected. Typically for the visual sense, these critical periods last anytime between birth and age 2. This critical development time is vital for correcting and even reversing any visual deficiency as the brain is still developing the neural pathways that develop the visual system. Studies also show that even beyond age 2, some vision problems such as amblyopia can still be reversed up until age 6. On the flipside, the success rate of vision correction seems to decrease with age.
Cats and the Critical Period for Development of Vision
The idea behind the importance of critical periods for the development of visual systems in the brain is critical to helping scientists find a way to restore sight to the blind. The premise behind the research done by the researchers from the University of Montreal and the University of Trento, explained by the results from a 1960’s experiment performed by David Hubel and Torsten Wiesel.
In their research, Hubel and Wiesel sutured shut the eyelids of both kittens and adult cats to study the neural pathways of the visual system. They found that if a kitten is deprived of a normal vision experience at the very start of its life, the neural pathways that link the visual system simply do not connect to create one. They also found that if the same process was repeated in an adult cat, the response cells in the cat’s visual cortex remained the same as the cells in the visual cortex of a normal cat.
Later experiments performed by these two men showed that suturing an adult cat’s eyelids posed no effect or reorganization of the cat’s visual cortex. The only time this visual deprivation affected the cat’s vision system was when the cat’s eyelids where sutured during the first three months of its life.
Neuroplasticity and Restoring Eyesight
The scientists from the University of Montreal and University of Trento, have shown that the visual system in the brain maintains a certain degree of neuroplasticity, even in adults who have had very low vision for their whole lives. These scientists had the opportunity to study and research the brain of a 50-year-old woman from Quebec who had experienced low vision throughout her entire life. By tracking behavioral and neurophysiological changes pre and post surgery, they were able to track the changes in her brain anatomy due to her changes in eyesight.
The premise for this research was based from the idea that just as the brain reorganizes to replace lost vision, brain reorganization can be reversed in the hopes of restoring eyesight. In the study, they implanted an artificial cornea in the woman’s right eye and measured changes in her brain using MRI imaging scans.
The findings of this study revealed that the visual cortex retained some degree of plasticity in patients with low vision, even in adulthood. This has given scientists the hope that restoring sight is a possibility. The question that needs answering now is what makes the difference in reversing brain reorganization to restore sight, even if it is not in its entirety.