Eye health is often associated with factors such as age, visual hygiene and family history. More and more research is showing that the gut-eye axis is a crucial link between gut microbiota and visual health. Indeed, this key and often neglected player is emerging more and more in scientific research: the intestinal microbiota. This complex group of micro-organisms that inhabit our digestive system plays a decisive role in the overall balance of our body, including our vision. This article explores the gut-eye axis, its implications for eye diseases and possible therapeutic strategies.
What is the intestinal microbiota?
The intestinal microbiota is a complex ecosystem made up of trillions of micro-organisms such as bacteria, viruses, fungi and archaea. These micro-organisms live in harmony in our intestine, where they play a crucial role in essential functions such as digestion, regulation of immunity and even brain function.
The main bacterial groups, called Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria, produce essential compounds such as short-chain fatty acids(SCFAs). These molecules help to reduce inflammation and maintain the integrity of the intestinal barrier, a key element in overall health.
A balanced microbiota supports robust immunity. When this balance is disturbed, we speak of dysbiosis, a condition that can affect not only your general health but also that of your eyes via the gut-eye axis.
What is the gut-eye axis?
The gut-eye axis refers to a network of complex biological interactions linking the gut microbiota to eye health. This link is based on precise scientific mechanisms. The intestinal microbiota plays a crucial role in immune modulation by influencing the body’s immune cells. Through the production of cytokines with anti-inflammatory properties and the regulation of regulatory T lymphocytes(Tregs), this microbiota helps to maintain an immune balance that protects the whole body, including ocular tissues.
How does the intestinal barrier protect the eyes?
The intestinal barrier, which acts as a bulwark against toxic substances, is also essential to this system. When it becomes excessively permeable, a phenomenon known as “intestinal hyperpermeability” occurs. In this situation, bacterial toxins such as lipopolysaccharides(LPS) enter the bloodstream. Once in circulation, these molecules can reach ocular tissues and trigger inflammatory responses, likely to contribute to the onset of chronic diseases such as diabetic retinopathy or age-related macular degeneration.
This dynamic clearly illustrates how the gut-eye axis influences visual health and why it is crucial to preserve a functional intestinal barrier.
Can intestinal disturbances affect the eyes?
Dysbiosis in the gut microbiota can indirectly disrupt the ocular microbiota, altering the composition and function of the local microflora on the surface of the eye. This imbalance can encourage the onset of disorders such as dry eyes and conjunctivitis. The gut-eye axis therefore illustrates a dynamic, bidirectional relationship, in which alterations to the gut can have repercussions on visual health. As a result of these interactions, it becomes clear that maintaining a balanced gut microbiota is essential for preventing and limiting eye disorders linked to inflammation or a dysregulated immune system.
Eye diseases linked to intestinal dysbiosis
The links between intestinal dysbiosis and certain eye diseases are becoming increasingly clear. Here is a summary table of the main diseases concerned and their link with the intestine-eye axis:
| Pathology | Link with intestinal dysbiosis | Biological impact |
|---|---|---|
| Age-related macular degeneration (AMD) | Dysbiosis leads to chronic low-grade inflammation, with an increased presence of pro-inflammatory bacteria such as Escherichia coli. | Damage to retinal tissue and acceleration of degenerative processes. |
| Diabetic retinopathy | An unbalanced ratio between Firmicutes and Bacteroidetes promotes systemic inflammation and increased permeability of retinal vessels. | Progression of retinopathy with alteration of retinal microvascularisation. |
| Glaucoma | Associated with neurodegenerative inflammation, exacerbated by imbalances in the intestinal microbiota. | Damage to optic neurons and increased intraocular pressure. |
| Ocular dryness | Resulting from an alteration in the ocular microbiota, itself influenced by intestinal dysbiosis via the gut-eye axis. | Disruption of tear production and chronic inflammation of the ocular surface. |
Intestinal dysbiosis acts as a catalyst for systemic and local inflammation. By upsetting the immune balance and promoting pathological mechanisms, it can aggravate a number of chronic eye diseases. This table highlights the link between intestinal microbial imbalances and their repercussions on visual health.
How can the gut-eye axis help to maintain eye health?
An appropriate diet is essential to rebalance the intestinal microbiota and protect visual health. Prebiotics, such as dietary fibres like inulin, encourage the growth of beneficial bacteria, thereby strengthening the intestinal ecosystem. At the same time, probiotics, in particular specific strains such as Lactobacillus rhamnosus or Bifidobacterium breve, play a key role in reducing systemic inflammation, limiting the deleterious effects on ocular tissues.
How can nutrition help protect your eye health?
Foods rich in omega-3, such as oily fish or linseed, provide essential fatty acids capable of modulating inflammation and directly supporting the retina. These nutritional elements help to maintain an intact intestinal barrier, limiting the translocation of bacterial toxins into the systemic circulation, a mechanism often involved in chronic eye disease.
What innovative therapies for a balanced microbiota?
Among the therapeutic advances, faecal microbiota transplantation stands out as a promising solution. This technique involves restoring a disturbed microbiota by introducing healthy microbial communities, with encouraging results in reducing chronic inflammation.
Synbiotics, which combine prebiotics and probiotics, also offer a synergistic approach to restoring microbial balance. By acting simultaneously on the growth and diversity of beneficial bacteria, these combinations boost immune defences and reduce the impact of microbial imbalances on ocular tissues.
Finally, external factors such as regular physical activity and stress management have a positive influence on the microbiota. Exercise improves microbial diversity and promotes intestinal motility. Effective stress management reduces cortisol levels, thereby minimising disturbances to intestinal permeability and their effects on the gut-eye axis.
The gut-eye axis represents a fascinating connection between digestive health and eye health. By adopting a nutrient-rich diet, innovative therapies and healthy lifestyle habits, you can preserve the balance of your microbiota and effectively protect your vision.
Sources
- Tîrziu A-T, Susan M, Susan R, Sonia T, Harich OO, Tudora A, Varga N-I, Tiberiu-Liviu D, Avram CR, Boru C, et al. From Gut to Eye: Exploring the Role of Microbiome Imbalance in Ocular Diseases. Journal of Clinical Medicine. 2024; 13(18):5611. https://doi.org/10.3390/jcm13185611
- Haghshenas L, Banihashemi S, Malekzadegan Y, Catanzaro R, Moghadam Ahmadi A, Marotta F. Microbiome as an endocrine organ and its relationship with eye diseases: Effective factors and new targeted approaches. World J Gastrointest Pathophysiol 2024
- Scuderi G, Troiani E and Minnella AM (2022) Gut Microbiome in Retina Health: The Crucial Role of the Gut-Retina Axis. Front. Microbiol
