Since the Human Microbiome Project launched in 2007, immense information has been produced about the gut microbiome. Discovery of the inter-relationships between the gut and other tissues like the eye in the body has been a new topic of increasing interest in just the last few years.

The recently discovered “gut-retina axis” describes a delicate inter-relationship between gut flora, immune cells that signal the retina, and the eye microbiome. This discovery has brought new perspectives on many common eye disorders like macular degeneration, dry eye disorder, glaucoma and others.

Gut Concerns Affect the Rest of the Body

When your gut is unhappy, you feel miserable all over. The rumbling, burping, belching, bowel gas, and urgent trips to the restroom reflect obvious gut distress. Overgrowth or imbalanced germs within the gastrointestinal tract drive many of these symptoms. Sometimes, gut symptoms may seem so slight that you feel like your gut is relatively healthy, yet there might be subtle symptoms elsewhere in the body.

Gut flora imbalances and its consequences affect the body elsewhere that you may not always equate together. Fatigue, headaches, skin problems, joint pain, obesity, poor blood sugar regulation, cholesterol, asthma and numerous autoimmune disorders are linked with imbalanced gut flora. Dry eyes, itchy eyes, red, swollen eyes, and even vision changes may occur and seem isolated, unrelated to anything else. These symptoms however may reflect changes in natural eye microbiome and its inter-relationship with the gut flora and gut-immune changes.

Eye Disorders

Cutting-edge research from April 2019 and other recent findings suggest that several eye disorders are linked with eye microbiome changes. Age-related macular degeneration (AMD), Sjogren’s syndrome-associated dry eye, uveitis, blepharitis, diabetic retinopathy, glaucoma, fungal keratitis, and corneal ulcerations are some recently recognized concerns. These ocular concerns affect hundreds of millions of individuals across the globe often with the threat of disability and vision loss.

The eye microbiome is distinctly different than what is on your face or in your mouth. It is even more profoundly different compared to the gut microbiome with the type and amount of flora. Until recently it was thought that the eye was sterile as it was very difficult to culture the normal eye flora and prove its existence.

Studies indicated that the gut flora and immune compounds interact on many different levels with the retina of the eye and its microbiome. An unhealthy, disrupted gut microbiome and activated immune cells trigger inflammation directly in the eye and impacts the retina, eye microbiome, and eye lubrication that lead to the disorders described above. We must incorporate this knowledge to help support the precious gift of sight.

The Eye Microbiome

When your eyelids are open, the eyeball is constantly exposed to all kinds of things in the environment. The eye is protected from the various elements in part by its own unique microbiome or beneficial flora. The eye microbiome is located on the tear ducts, eye lids, and conjunctiva. The conjunctiva is a fine, transparent, layer of tissue that covers the white part of the eye and lines the inner surface of the eyelid. The white part of the eye is the sclera.

Things That Affect the Eye Microbiome

Several things have been identified that change the eye microbiome. For instance, individuals who wear contact lenses have a different balance of ocular flora compared to non-wearers. There is less diversity and a greater tendency to develop eye infections, keratitis and giant papillary conjunctivitis as a result of the changed eye microbiome in those who wear contact lenses. Even some of the newer methods of vision correction with orthokeratology, (“Ortho-K” or “vision shaping”) which uses contact lenses to reshape the cornea for visual acuity changes the eye microbiome giving rise to increased eye infections.

Topical antibiotic eye drops, some preservatives in glaucoma eye drops, and tear duct punctal plugs used to treat dry eye also change the eye microbiome. Eye microbiome changes also occur with age, dry eye disorders, diabetes, and other systemic diseases. High glycemic diets adversely change the eye microbiome, whereas low glycemic diets are helpful to the eye microbiome. Gut disorders and treatment with medications like antibiotics affect the gut microbiome and the intestinal lining which in turn affects the eye microbiome.

Changes Related with Gut Barrier and Eye Lubrication

Physical changes of the eye are thought to be due to inflammation in the gut lining linked with increased intestinal permeability. Changes in intestinal permeability/Leaky Gut Syndrome allows germs, their toxins, or immune compounds to cross over the mucosal gut barrier and travel to various locations including to the surface of the eye. These compounds directly affect the eye or may trigger an immune reaction in the eye via molecular mimicry. Molecular mimicry is a mechanism that may trigger autoimmune inflammation because of damaged to the protective barriers and the chronic presence of germs or toxins.

Eye Lubrication and Tears

Dry eyes and eye lubrication is another area of great interest for the eye microbiome. Moisture is a type of barrier that helps protect the structure and function of the eye. Your eyes must be sufficiently lubricated to keep the ocular flora healthy. Just like the gut lining and respiratory tract have mucous to help their microbiome, your tears play a role in protecting the eye. Dry eyes and diminished eye lubrication are in great need for a healthy eye microbiome. Nearly 10 percent of adults in the U.S. have dry eye disease, the most common disorder seen by optometrists.

Blinking

Blinking is one way to refresh the normal tear film in the eye. It also helps to remove debris, environmental toxins, and germs from the conjunctiva of the eye. If you spend hours a day intently focusing or looking at a computer screen, reading or driving, this decreases the number of times you blink each minute. Multiply lack of blinking by hours days, and weeks that this occurs and think about its role in the development of your dry eyes. Make sure you take appropriate rest breaks to give your eyes a break.

Tears, Secretory IgA, and Conjunctiva

The tear film is considered vital to the ocular surface and microbiome. Tears are not simply a salty fluid. Tears contain many different compounds critical to eye health and its microbiome. Natural antimicrobials are present in the tears that can kill germs on contact and simultaneously call upon other immune cells to help manage.

One of the compounds found in the tear film of the eye is secretory IgA (sIgA). This compound is known for its essential role in keeping germs and allergens from attaching to the mucosal lining of the respiratory and gastrointestinal tracts. sIgA functions similarly for the eye and is also necessary for the production of mucin and lipids that lubricate the surface of the eye.

The conjunctiva layer, which is the thin translucent layer on top of the sclera or white part of the eye and epithelial cells on the cornea, contributes to the mucosal layers of the eye. They are involved with triggering T cells and B cells, cytokines, and other immune cells to fight off pathogens, and affect the eye microbiome.

Eye Support

Eye research and its microbiome is still very new with more discoveries every month. As scientists sort out this information, you can support your eye microbiome with some fundamentals. Focus on maintenance of adequate eye moisture and tear film by supporting sIgA. Consume plenty of antioxidants for the eye, and make sure to support healthy gut flora. Reduce exposure and protect your eyes from technology that emits blue light.

Secretory IgA production requires several nutrients. Critical nutritional support includes vitamin A, glutamine, omega-3 fish oil, fiber, boswellia, glutathione, colostrum, lactoferrin, probiotics, rhodiola rosea, quercetin, vitamin C, and zinc. Many of these same nutrients help support and energize your immune system. 

Vitamin A, beta carotene, lutein, lycopene, lipoic acid, vitamin C, zinc, prebiotics, probiotics, curcumin, resveratrol, quercetin, grape seed extract, green tea extract, omega-3 DHA/EPA, and omega-6 GLA are vitally essential to eye health as they are antioxidants, support eye lubrication and positively support the eye microbiome. Many of these same nutrients support gut health too. Other nutrients like hyaluronic acid and N-acetyl-d-glucosamine are used to help eye moisture and lubrication just like they support joint lubrication and the gut mucosal lining.

As discussed in my last article, Curcumin Supports Gut Lining and Health, the gut microbiome is adversely affected by many things especially by high stress and the Western Diet of high calorie, high fat, high carb, nutrient poor foods. The Western Diet also provokes inflammation that readily stresses eye lubrication, local immune inflammation, the eye microbiome and lacks many of the nutrients needed for eye health.

Focus on a diet of at least 5-9 servings of richly colored fruits and vegetables per day, quality organic proteins, and healthy fats from cold water fatty fish, avocado, chia and flax seeds, olive oil, and low glycemic index complex carbs.

Even within the last few years, it thought that the eyes were sterile, yet cutting-edge research shows us that it is far from the truth. A few hundred years ago, mankind thought that everything including the sun revolved around the earth, but that was disproven and has since revolutionized the way scientists think about the earth and the universe. A similar phenomenon is occurring with the Human Microbiome Project with things like the eye microbiome and disorders pertaining to autoimmunity, Parkinson’s, Alzheimer’s, prenatal development, etc.

In this case, we are literally “seeing” what the eye microbiome does for keeping the eyes healthy and protecting eyesight. There is still much left to be learned and fully understood, but for now work on keeping your gut and your eye microbiome fortified and protected.