Sense of Sight

A vision for the future

Image credit: Alamy

Breakthroughs in human and machine vision are happening at speed, but even more exciting is what can be achieved when the two are combined.

Recent technological advances are having a transformative impact on a variety of retinal conditions including age-related macular degeneration (AMD) – the leading cause of permanent loss of sight in the adult population, affecting 200 million people worldwide.

In this disease, photoreceptors in the central retina gradually degenerate, resulting in the loss of high-resolution central vision, which impairs patients’ ability to read and recognise faces. An innovative implant developed in the US by researchers at Stanford University promises to help by replacing the lost photoreceptors with photovoltaic pixels. These convert light into electric current to stimulate the second-order neurons in the retina, thereby restoring the flow of information in the visual system.

“The implant is completely wireless, it’s powered by light, and it can be implanted relatively easily,” says Daniel Palanker, professor of ophthalmology at the university and lead designer of the prosthesis. “Clinical trials have demonstrated that, with our system, for the first time, prosthetic vision provides form perception – not just light sensitivity.”

Prosthetic visual acuity closely matches the 100-micron pixel size of the first-generation implant (PRIMA). The next-generation implant with 20-micron pixels has been successfully tested in rats. “If successful in the upcoming clinical trial, such an implant may enable 20/100 vision, which means a patient will be able to see from 20 feet what a person with normal vision would see from 100 feet,” Palanker says. “This is a five-fold improvement on the current implant. With an electronic zoom, patients could read the fonts corresponding to 20/20 vision,” Palanker said.

Meanwhile, CureSight – an amblyopia treatment system designed to replace traditional eye patching – has been designed by medical device company NovaSight. Amblyopia (otherwise known as lazy eye) is the leading cause of vision loss in children, resulting in reduced visual acuity and poor depth perception. It currently affects around 3 per cent of the world’s population.

The most used treatment option today involves placing a patch over the strong eye and using Atropine drops. “The traditional eye patch is known to be uncomfortable and leads to low compliance and social stigma,” says Ran Yam, NovaSight’s CEO.

CureSight takes a completely different approach. “CureSight is an FDA-cleared and CE-marked eye-tracking-based system designed for kids aged between four and nine,” Yam says. “It’s a binocular treatment which can improve both visual and stereo acuity by training the visual system to use both eyes simultaneously.”

The digital device works with red and blue treatment glasses, which the child wears while watching any streamed content of their choice. By tracking the gaze position of both eyes in real time, the CureSight system blurs the centre of vision of the dominant eye and provides the lazy eye with a normal sharp image. This stimulates the visual system to use the information coming from the lazy eye to process the fine details, improving its acuity and developing stereoacuity as the eyes learn to work together.

“Our pivotal study showed that adherence to the CureSight treatment is around 93 per cent, and 95 per cent of parents report that they are likely or very likely to choose the CureSight digital amblyopia treatment over patching,” says Yam.

Sense of Sight

Image credit: Alamy

Israel-based RevitalVision is also targeting amblyopia with its vision training software that enhances vision by targeting specific neurons in the visual cortex in the brain. “By using Gabor patches and a patented stimulation technique, it promotes neural connections at the cortical level, activates specific neurons in the visual cortex, and generates fresh neural connections at the synapse level, leading to sustained improvement in vision,” explains Yair Yahav, the company’s CEO.

RevitalVision is FDA-cleared and is the first solution to effectively treat amblyopia in adults. “Until now, amblyopia was considered untreatable after the age of nine,” Yahay says. “This is a major breakthrough.”

Yahav expects the technology to help with other conditions too. “An example is someone who has been unable to obtain a driver’s license due to their visual impairment; even a couple of lines improvement in their vision can be life-changing,” he says.

Advances in our human vision are also helping to revolutionise a very different kind of sight: machine vision. Taking inspiration from the eye of the Mantis shrimp, a research group at Eindhoven University of Technology in The Netherlands has developed a near-infrared sensor that is easy to make, comparable in size to sensors in smartphones, and ready for immediate use.

“The eyes of the Mantis shrimp have 16 different cells, which are sensitive to ultraviolet light, visible, and near-infrared light,” says Kaylee Hakkel, PhD researcher in the Department of Applied Physics and co-first author of a study that has recently been published in Nature Communications.

While measuring the spectrum in the infrared is most interesting for applications in industry and agriculture, there’s one major issue – current near-infrared spectrometers are just too big and expensive. Hakkel and her collaborators have solved this issue by developing a near-infrared sensor that fits onto a small chip.

“We anticipate that the sensor could be used for personalised health care, precision agriculture (monitoring the ripeness of fruit and vegetables for instance), process control, and lab-on-chip testing,” says Maurangelo Petruzzella, co-first author of the study. “This sensor could even be commonplace in the smartphones of the future, meaning that people could use it at home to check the quality of their food or check aspects of their health.”

Meanwhile, advances by Swiss computer-vision specialist Basler are enabling vision-guided robots to have better object detection and localisation as well as better identification and sorting functions.

“Using stereo vision, our solution enables robots and machines to perceive their environment, to learn from it, and to act as we do as human beings,” explains Basler’s director of R&D innovation, Ralf Lay. “Combining this with AI technology results in something very similar to how we humans adapt and interact with the world around us.”

Basler’s vision solutions for robots can be used in a variety of applications. “Use cases range from classical picking from mixed and unmixed bins with unstructured parts in automotive, for example, or unloading pallets, automated order picking and packing in logistics,” says Sebastian von Holdt, Basler’s head of product management for 3D image acquisition.

Machine vision is also being refined at UK company Recycleye – a business that replicates the power of human vision to identify every item in entire waste streams, broken down by material, object and even brand.

“We are combining advanced machine learning, computer vision and robotics to revolutionise the waste-sorting process,” says Recycleye’s CEO, Victor Dewulf. “The vision system identifies and classifies different types of waste, including various types of plastics, metals, glass and paper, before sending this information to the robotic arm, which picks and sorts the classified items into designated locations.”

Dewulf says the solution not only lowers the cost of sorting, but increases plant performance and enables data-driven strategic decision-making in material recovery facilities on a global scale.

While these are all compelling examples, what’s perhaps even more compelling is when human and machine vision come together. Until recently, however, this has been a challenge. While several hundred bionic eyes have been successfully implanted over the years by US company Second Sight, the products – and the business – were eventually deemed economically unworkable.

“Getting that device to relatively few patients and supporting those patients with the resources we had simply wasn’t sustainable,” explains Uday Patel, director of clinical and scientific affairs at US company Cortigent, formerly Second Sight. “It simply wasn’t a viable business model.”

‘Optogenetics may be effective in the eye, since it is a relatively closed-off organ... but it will require a lot of bench research to establish safety and potential efficacy.’

Uday Patel, Cortigent

Things are about to change. The global bionic eye market is currently valued at $297m and is predicted to expand rapidly at a CAGR of 13 per cent from 2023 to 2033.

One of the frontrunners in the new race to deliver a solution is Max Hodak’s company Science. In November last year, he and his colleagues unveiled their flagship product: the Science Eye. It’s a combination device that uses an optogenetic gene therapy targeted at the cells of the optic nerve in conjunction with an implanted flexible thin-film, ultra-dense microLED display panel inserted directly over the retina.

However, it’s still early days. “There are significant challenges that the team behind Science Eye will have to overcome before their system can be used in humans,” Patel says. “Their technology requires the introduction of genetic material into the cells of the retina. This is accomplished by using viruses. The effectiveness of this technique can be very inconsistent due to variable expression of opsins [a type of light-sensitive protein] and to immune responses.”

This raises not just physiological challenges, but regulatory and ethical questions. “I love optogenetics as a tool for neuroscience research,” Patel says. “It may be effective in the eye, since it is a relatively closed-off organ. You may be able to safely introduce the virus into the vitreous and infect just the cells inside the eye, but it will require a lot of successful bench research to establish safety and demonstrate the potential for efficacy before regulatory agencies will allow their technology to be used in humans.”

However, Patel says Cortigent has made great headway with its new system – and it doesn’t require genetically modifying retina cells. “The Orion Visual Cortical Prothesis System is a novel medical device that seeks to provide artificial vision to patients with nearly all forms of profound blindness, including glaucoma, diabetic retinopathy, optic nerve injury or disease, or eye trauma,” he says.

Cortigent claims to be further along in the development process than any other cortical stimulation product for vision. “We have completed five years of an early feasibility study evaluating the safety, reliability and efficacy of our devices,” Patel says.

The next step in getting the Orion approved for marketing will be a pivotal study. “We’re currently in the process of designing that, but we are confident that the cortical implant technology we have developed offers capabilities well beyond other cortical stimulators on the market,” Patel continues. “That technology could be leveraged for other applications like recovery from stroke, pain, tinnitus, and depression. We’re incredibly excited about what the future holds.”

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