Can gene therapy cure blindness?

There’s a lot of coverage about new “genetic therapies” and techniques and whether or not they’re going to bring about a revolution in medicine.

From designer babies to stem cell therapy, every week there are stories that describe their promise as a miracle cure or layout their risks and explain why they should be avoided at all costs.

Gene therapy is a hot topic for the media and, as a treatment that can clearly help millions of people, it should be. But with much-overblown hype and misinformed articles, it’s important to get the facts straight.

Gene therapy is a largely unstudied and unproven domain. However, it has been proven as the only potential treatment for the rare eye condition, Leber’s congenital amaurosis. Leber’s congenital amaurosis is a life-limiting condition in which the eye is deteriorating since birth and sufferers of it can only see in bright light.

In particular, one young boy in the US, who took part in a clinical trial at the Bascom Palmer Eye Institute in Miami, Florida, experienced significant results from a gene therapy treatment. The ophthalmologists are unsure how much improvement he can expect to see, but his vision was reported afterwards as 20/30 with glasses in his better-seeing right eye, and his worse-seeing left eye as slowly improving.

It is cases like this that give hope to millions of people suffering from eye conditions, both rare and common. To get a better idea if the promise is to be believed or it really is just hype, let’s dive in and discover what exactly is gene therapy and where the field is today.

What is gene therapy?

Gene therapy is a term that describes new medical techniques that attempt to use genes to treat or prevent disease.

It typically works by using a harmless virus to deliver healthy copies of genetic material into cells. This genetic material compensates for abnormal genes or helps to make protein. If a mutated gene is to blame for a necessary protein that is faulty or missing, the idea is that the normal copies of the gene may help restore the function of the protein.

Gene therapy is a promising treatment for a number of diseases, including some types of cancer, genetic disorders, and certain viral infections. However, in most cases, the technique is experimental and still being studied to figure out if it is safe and effective in humans.

Much of the research and testing of gene therapy today is with rare diseases that have no other cures. In the future, the technique may be available for a wide number of diseases and conditions, offering an alternative to many drugs and invasive surgeries.

Today, we are very much in the early days of gene therapy. So although there are many therapies being offered by private companies, most haven’t yet been proven effective or tested for safety on people through rigorous clinical trials.

Gene therapy for Age-Related Macular Degeneration (AMD)

In 2019, a woman from Oxford in the UK became the first person in the world to receive gene therapy for age-related macular degeneration.

As part of a clinical trial at the Oxford Eye Hospital, surgeons injected a synthetic gene into the back of her eye with the aim of preventing more cells from dying and stopping the condition from progressing.

In a report by the BBC, one of the doctors at the hospital said, “A genetic treatment administered early on to preserve vision in patients who would otherwise lose their sight would be a tremendous breakthrough in ophthalmology and certainly something I hope to see in the near future.”

All those participating in the trial had what’s known as dry AMD, the most common form of the condition. Dry AMD is when the decline in vision is gradual and can occur over many years. As it progresses, dry AMD can develop into wet AMD, in which there is the risk of severe vision loss.

The trial was designed to check the safety of the procedure and was the first of its kind to use gene therapy to target the underlying genetic cause of AMD. As a recent, small, and early-stage trial, it’s too early to tell whether or not the treatment has had a repeatable effect.

However, at the very least, gene therapy is safe, with one treatment soon to be available through the NHS for retinal dystrophy.

There is, in fact, already one gene therapy available for another rare eye disorder. In 2016, the same team in Oxford demonstrated that an injection could improve the vision of people with choroideremia. Choroideremia specifically affects young men whose light-detecting cells in the retina are dying due to a faulty gene. The disorder has no treatment or cure, and without gene therapy, it eventually leads to blindness.

AMD, however, is a much more common condition. Around 600,000 people in the UK alone are affected by AMD, with over half being severely sight impaired. Hopefully in the future gene therapy can help prevent that number from growing, and even restore vision to those who through the condition have lost it. Here, we are participating in a number of clinical trials for retinal disease, you can find out more information here.

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