With billions of individual organisms and up to 2 kilograms of total mass, the microbial community in the human intestine is a serious factor for health. From obesity to Alzheimer’s dementia, many diseases are associated with a disturbance of the microbial balance. Recent studies now indicate for the first time that the influence of the microbiome could also reach into the eye. Whether and how the intestinal flora influences the development and course of age-related macular degeneration (AMD) will be a topic at the hybrid press conference on September 25, 2025 on the occasion of the Congress of the German Ophthalmological Society (DOG) in Berlin.

Age-related macular degeneration (AMD) is a veritable widespread disease with around 7 million people affected in Germany. “According to estimates, the retinal disease affects around one in 4 people over the age of 65 in Germany,” says PD Dr. Dr. med. Petra Larsen, who works at the University Eye Clinic in Bonn and will present the topic at the press conference. In the course of the chronically progressive disease, the area of sharpest vision in the center of the retina loses more and more of its function. “In industrialized countries, AMD is the most common cause of blindness,” says DOG expert Larsen, emphasizing the importance of the disease.

Intestinal flora can promote inflammation

Despite intensive research, it is not yet fully understood which mechanisms are at work in the development of AMD. What is certain, however, is that in addition to age as the most important risk factor, family predisposition also plays a role. Smokers are also affected more often than non-smokers. Chronic inflammation and other misguided immune processes have emerged as other significant influencing factors. “Such imbalances and dysregulation in the immune system are also observed in connection with disorders of the intestinal microbiome,” explains Larsen.

Intestinal substances can penetrate to the retina

An unfavorable shift in the microbiome composition, a so-called dysbiosis, can occur due to an unhealthy diet, chronic stress, illnesses or the use of medication, among other things. The dysbiosis itself can then have far-reaching consequences for the whole body. Under their influence, the intestinal wall can become more permeable, so that bacterial components as well as bacterial metabolites and pro-inflammatory substances enter the bloodstream. “Experimental studies indicate that these substances can also enter the tissue of the retina, which is actually immunologically protected,” reports the ophthalmologist. The assumption is therefore obvious, Larsen continues, that they could also be involved in degenerative processes in the retina. “Further evidence of a connection between intestinal flora and AMD comes from studies that have shown differences in the composition of the microbiome in subjects with and without AMD,” adds the DOG expert.

Editor: X-Press Journalistenbüro GbR

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