Audio Captions

Did you see this interesting item on Seven Sharp about audio captions? The story ran on World Sight Day, and is another example of technology helping people with vision loss stay connected and engaged. Audio describing reveals all the on screen details, which are a very important part of the story.

Able, a New Zealand Company develops the audio descriptions and have a very informative website.

One of the challenges for people with low vision is the practical aspects of setting up access to these new technologies. This is where support from sighted friends and families is so valuable. And it is always a good idea to have a try at some of these things, even when you don’t need them.

Able Editing Audio Captions

Human Retinas Grown in a Dish Explain How Colour Vision Develops

This report caught my eye. Science once again pushing the frontiers. Biologists at Johns Hopkins University have grown human retinas from scratch to determine how cells that allow us to see in colour are made. This lays the foundation for therapies for eye diseases such as colour blindness and macular degeneration.

These lab-created “organoids” are a model to study human development on a cellular level. “Everything we examine looks like a normal developing eye, just growing in a dish,” said Robert Johnston, a developmental biologist at Johns Hopkins. “You have a model system that you can manipulate without studying humans directly.”

Johnston’s lab explores how a cell’s fate is determined – or what happens in the womb to turn a developing cell into a specific type of cell, an aspect of human biology that is largely unknown.

His team focuses on the cells that allow people to see blue, red and green – the three cone photoreceptors in the human eye.

While most vision research is done on mice and fish, neither of those species has the dynamic daytime and colour vision of humans. So Johnston’s team created the human eyes they needed — with stem cells.

“Trichromatic colour vision delineates us from most other mammals,” said lead author Kiara Eldred. “Our research is really trying to figure out what pathways these cells take to give us that special colour vision.”

Over months, as the cells grew in the lab and became full-blown retinas, the team found the blue-detecting cells materialised first, followed by the red- and green-detecting ones. In both cases, they found the key to the molecular switch was the ebb and flow of thyroid hormone. Importantly, the level of this hormone wasn’t controlled by the thyroid gland, which of course isn’t in the dish, but entirely by the eye itself.

Understanding how the amount of thyroid hormone dictated whether the cells became blue, or red and green, the team was able to manipulate the outcome, creating retinas that if they were part of a complete human eye, would only see blue, and ones that could only see green and red.

The finding that thyroid hormone is essential for creating red-green cones provides insight into why pre-term babies, who have lowered thyroid hormone levels as they are lacking the maternal supply, have a higher incidence of vision disorders.

“If we can answer what leads a cell to its terminal fate, we are closer to being able to restore colour vision for people who have damaged photoreceptors,” Eldred said. “This is a really beautiful question, both visually and intellectually – what is it that allows us to see colour?”

These findings are a first step for the lab. In the future they would like to use organoids to learn even more about colour vision and the mechanisms involved in the creation of other regions of the retina, such as the macula. Since macular degeneration is one of the leading causes of blindness in people, understanding how to grow a new macula could lead to clinical treatments.

“What’s exciting about this is our work establishes human organoids as a model system to study mechanisms of human development,” Johnston said. “What’s really pushing the limit here is that these organoids take nine months to develop just like a human baby. So what we’re really studying is fetal development.”

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A Miracle.

This recent story caught my eye and is worth sharing. New Zealand author Lynley Hood has been a strong advocate for the visually impaired community since she lost her own vision in 2009.

Visual Impairment Charitable Trust Aotearoa (VICTA) started as a result of her lonely and frustrating search for help. VICTA provides an independent consumer voice for New Zealanders with irreversible vision loss who are not blind enough to qualify for membership of Blind Low Vision New Zealand (BLVNZ).

She has also written eloquently about ‘Becoming Illietrate’ where she describes her frustartion with listening to audio books, and her grief at the loss of being able to read text. This is an evocative piece for anyone who loves reading, describing all the pleasure we derive from text and the written word.

Author Dr Lynley Hood

Now, so far unexplained, she has recently regained her vision. This has baffled medical specialists. I suspect she won’t be stopping to consider the why and how, instead I imagine her immersed again in her joy of reading. Read more in this article.