Scientists have discovered another cause of vision loss – intestinal microflora

There are many different causes of vision loss, for example, it can occur due to infections such as conjunctivitis or keratitis, insufficient blood circulation, loss of sensitivity of the optic nerve, changes in the shape of the eyeball, etc. A recent study by scientists from China and the UK showed another, very unobvious cause of vision loss – intestinal bacteria. They can impair peripheral and night vision and can also cause complete blindness. Moreover, bacteria cause visual impairment at an early age, although this becomes possible only if there is a mutation in one of the genes.

Scientists have discovered another cause of vision loss - intestinal microflora. Scientists have discovered a relationship between vision and intestinal bacteria. Photo.

Scientists have discovered a relationship between vision and gut bacteria

How gut bacteria are linked to vision

A team of scientists conducted a study on mice, during which they found bacteria from the gut in damaged areas of the eyes. However, these bacteria were only present in rodents that had mutations in the gene (CRB1). It should be noted that mutations in the same gene are the main cause of hereditary eye diseases in humans.

Eye diseases associated with this mutation occur at an early age due to abnormalities in the retina. Recall that the retina is the tissue at the back of our eyes that converts light waves into specific signals that travel to the brain. There these signals are converted into a picture (vision). Due to damage associated with the gene mutation, the retina becomes abnormally thick, resulting in less efficient performance of its task.

How intestinal bacteria are related to vision. Intestinal bacteria presumably damage the retina of the eye. Photo.

Intestinal bacteria suspected of damaging the retina

However, the presence of bacteria in damaged areas of the eye does not mean that they are the cause of the problems. To find out whether the bacteria cause vision problems, scientists reduced their population in the eyes of some rodents. After this, they reportedly did not experience significant retinal damage, as in other mice with the gene mutation. Additionally, when they restored expression of the Crb1 protein, which is encoded by the CRB1 gene, the mice had less retinal damage. The study authors report this in the journal Cell. As it turned out, this protein directly affects the presence of bacteria in the eye.

Why intestinal bacteria cause vision loss

Most gut bacteria are beneficial and play an important role in human health. However, the CRB1 mutation, according to scientists, allows gut bacteria to reach the eyes, where they cause vision loss.

The Crb1 protein mentioned above was previously thought to be present only in the brain pigment epithelium and retina (RPE), i.e. external barrier between the blood and the retina. However, the researchers also discovered that the protein is also expressed in the intestinal wall. There it provides a vital barrier between the intestines and the rest of the body.

Why intestinal bacteria cause vision loss. Due to mutations in genes, intestinal bacteria can enter the bloodstream. Photo.

Due to mutations in genes, intestinal bacteria can enter the bloodstream

The mutated CBR1 gene does not express a sufficient amount of the Crb1 protein , causing the barrier to become less effective, allowing bacteria to spread throughout the body. In particular, through the bloodstream they enter the retina of the eye, and this leads to its damage.

Now scientists just have to figure out the main thing – whether this mechanism really causes blindness in people, and whether treatments aimed at eliminating bacteria from the eye can prevent blindness. Therefore, the team is planning to conduct clinical studies in the near future.

Gene therapy for eye diseases

A study has shown a possible reason for the link between eye diseases and a single gene mutation. However, there are about a hundred other genes that also affect the light-sensitive photoreceptor cells of the retina. They can cause a variety of diseases, such as retinitis pigmentosa. At least 28 more genes are associated with Leber congenital amaurosis.

Gene therapy for eye diseases. Gene therapy is a promising area of ​​ophthalmology. Photo.

Gene therapy — a promising direction in ophthalmology

Therefore, gene therapy is a promising direction in ophthalmology. Therefore, scientists hope that further research will allow us to develop new methods of treating many diseases that are currently considered incurable.

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Finally, let us remind you that intestinal bacteria affect many other functions of the body. For example, scientists previously linked disturbances in the intestinal microflora to chronic fatigue. Also, a number of studies have shown that bacteria affect brain function and mobility may even depend on them.


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