As you read this passage, the fact that you have the ability to see and read might not even cross your mind. There are a lot of people who are not as fortunate. According to the World Health Organization (WHO), 285 million people are estimated to be visually impaired worldwide. Of these, 39 million are blind and 246 million have low vision.
Most frequently, visual impairment is caused by uncorrected refractive errors (43%) or cataracts (33%). Refractive errors include myopia, or short-sightedness, hyperopia, or far-sightedness and astigmatism, whereby the cornea or lens does not have a perfectly curved shape.
When visual impairment is caused by these problems, often treatment is readily available. Refractive errors can be corrected with glasses, contact lenses or refractive surgery. Cataracts – the clouding of the lens – are commonly treated with a surgical procedure that is among the most frequently carried out in the US.
While 80% of visual impairment can be prevented or cured, there remains 20% of cases for which there is currently no way of curing. A range of conditions exists where those who develop them are faced with a gradual loss of vision until their impairment is so severe that they are effectively blind.
The eye lends itself to experimental treatments, being easy to operate on and often protected from inflammatory responses that could disrupt therapies. Due to its accessibility, surgeons can also easily observe and track how new treatments are progressing.
There is a form of treatment, that has led to the restoration of vision in patients with advanced forms of retinal degeneration disorders. Just as prosthetics can be used to restore function to individuals that have lost limbs, so too can individuals who have lost their vision use retinal prostheses.
A camera connected to a pair of glasses transmits visual information to a small chip attached to the back of the eye via a small computer worn in a belt pack. The chip can send light signals directly to the optic nerve, bypassing the damaged retina and providing the patient with visual information in the form of flashes of light.
The World Health Organization state that over the past 20 years there has been significant progress in preventing and curing visual impairment in many countries around the world. In 2013, the World Health Assembly approved the 2014-19 Action Plan for the universal access to eye health. The aim of this plan is to reduce avoidable visual impairments by 25% by 2019.
While many people believe that the loss of vision is one of the health problems that could have the biggest impact on everyday life, it is encouraging to think that visual impairment is no longer as absolute a prospect as it once was.
Thanks to prosthetics, people who have lost legs can walk around unaided, with most people unaware that they have any limbs missing. It is not too hard to now envisage a future world in which people could be cured of blindness, with any hints of their previous disability remaining invisible.
CRISPR is a gigantic breakthrough in genetics, says Stephen Daiger, a professor of environmental and genetic sciences and ophthalmology at the University of Texas Houston Health Science Center. “It’s relatively inexpensive and conceptually easy to do, but we’re still at the very early stages of doing this with humans and working on the retina,” Daiger says. “If I had to bet on where the big breakthroughs are going to be over the next (decade), I’d have to say its gene editing.”
On the plus side, CRISPR may be the only option for diseases caused by genes that are too large to fit in a viral carrier, kind of like a taxicab. Some also see CRISPR and the idea of repairing rather than replacing a gene as a simpler approach to treating disease.
Within roughly the past decade, efforts in two other areas, stem cells and biomedical, or “bionic,” implants, have also given at least some sight to people previously sightless. Stem cells—cells in early stages of development, before they differentiate into the building blocks of eyes, brains, arms, and legs—show increasing promise to replace or revive the failing retinal cells that underlie many causes of blindness.
These advances encourage talk of something unthinkable just 10 or 20 years ago: ending human blindness, and soon.
