Stem cells used to treat children’s cataracts
The recent publication of a study from China and the USA, in the journal Nature, is one of the most exciting new stories in the world of cataract medicine. The study contains the use of stem cell regeneration of lenses in children who had congenital cataract. (1)
I see the majority of cataracts in adults over the age of 55. Sadly, children can also be born with congenital cataracts – though, this is rare in England. Early diagnosis and removal of these cataracts in children is vital to ensure that children do not develop lazy eyes and poor vision. If congenital cataracts are removed early, then children have the best chance of developing a good vision for the rest of their lives.
Cataract surgery in children is relatively similar to cataract surgery in adults. The great challenge has been how to replace the cataract after its removal. Options include leaving the child without a replacement artificial lens (aphakia). The child is providing thick corrective glasses or contact lenses to allow the child to focus after surgery.
Other options include inserting an artificial intra-ocular lens inside the eye. This procedure allows focusing (pseudophakia). But it can be difficult to manage in later years as the eyeball grows. Furthermore, thick and cloudy membranes on the back surface of the artificial lens can develop.
The ground-breaking study from China and San Diego had surgeons conduct cataract surgery on 12 children (under two). They used a different technique. The main difference to conventional cataract surgery was the investigators. They made a much smaller opening into the cataract capsular bag once inside the eye. This was so small that it self-sealed afterwards. Interestingly this is one prediction I made in my blog post: ‘Cataract surgery in 2040’. Afterwards, they removed the cataract in a conventional way but left the inner lining of cells in the capsular bag. This is known as lens epithelial stem cells.
Leaving these lens epithelial stem cells in the eye allowed them to cleverly regenerate a new clear lens that filled the capsular bag. This could then provide a clear view to the back of the eye for focusing without the need for an artificial intra-ocular lens inside the eye.
The researchers compared this surgical technique to the conventional cataract surgical technique. They showed that the children did well with the new technique. Furthermore, the new technique had lower complication rates.
This study is very exciting work. But we must note that the study was small and we do not have long-term follow-up data for the children who were initially studied. Larger long-term studies need to be conducted to confirm these initial findings and to show that its beneficial effects last.
The other thing to note is that this new surgical technique is unlikely to work in adults with age related cataracts. This is because as we age, the number of lens epithelial stem cells that line the capsular bag declines. Removing an adult cataract and leaving the very small number of lens epithelial stem cells is not sufficient to regenerate a whole lens. For now, we will still have to replace the cataract with an artificial intra-ocular lens.
Future work in adult cataract surgery may look at inserting external lens epithelial stem cells (possibly grown in the laboratory) to regenerate a whole new clear lens but that, unfortunately, may be some years away.
Fortunately, our adult cataract surgery technique at present is excellent with very few complications. Current cataract surgery produces excellent results in about 96% of patients. It is still an excellent option to restore vision.
The question also remains – if cataract surgery produces such good results now, do we even need stem cell regeneration technology?
If you have any questions about cataracts, how they develop, and how to remove them successfully, please call me on 020 7305 5063. I would happy to discuss your specific needs in detail.
1) Lin H, Ouyang H, Zhu J, et al. Lens regeneration using endogenous stem cells with gain of visual function. Nature. Published online March 9 2016