Eye spy: Exploring the mouth-eye connection

It’s no surprise to dental professionals that a healthy mouth is essential to overall health and well-being. But could a healthy mouth also lead to healthier eyes? New research suggests that infection and inflammation can travel between the mouth and the eyes. Dental hygienists are poised to provide valuable education and prevention regarding oral health and eye health, including potential vision problems and blindness.

With the infectious route, the bacteria move from the oral cavity and metastasize to the eye. The eye, like the mouth, skin and gut, has a unique and individualized microbiome. Factors that can influence the composition of the ocular microbiome include ethnicity, geographic region, age, contact use, and oral health.1

Harmful pathogens can enter the bloodstream and lymphatic system and travel throughout the body to the eyes. Dysbiosis can occur when bacteria, viruses, fungi, and parasites disrupt the normal eye microbiome. Eye diseases are more likely to appear when the microbiome is out of balance. Some examples of eye diseases associated with non-eye microbes include dry eye syndrome, keratitis, blepharitis, and conjunctivitis. High bacterial loads in the oral and intestinal parts of the body, including Bacteroides and Prevotellehave been implicated in an altered ocular microbiome.2

In 2017, a study published in the Glaucoma Diary concluded that poor oral health, an altered oral microbiome, and the number of missing teeth can all be considered risk factors for the pathology of glaucoma.3 With all types of glaucoma, the optic nerve at the back of the eye that connects the eye to the brain is damaged (Figure 1). With the inflammatory pathway, the highly vascular supporting periodontal structures around the teeth are damaged by harmful periodontal bacteria. The host’s inflammatory response is triggered. Chemicals in the form of histamine, bradykinin and prostaglandins are released by damaged cells. This results in tissue swelling caused by chemicals leaking into the surrounding blood vessels. The inflammatory cascade is marked by inflammation throughout the body, which increases pressure around the eye. Increased pressure in the eye irritates or damages the optic nerve. In the June 2021 issue of Investigative ophthalmology and visual sciencesthe research corroborated previous scientific studies regarding the association between poor oral health and primary open-angle glaucoma (POAG).4


Further reading: Jenn’s Vision: Eye Injury Victim Becomes Eyewear Advocate for Dental Patients


Glaucoma is classified as a progressive disease of the optic nerve. POAG is the most common form of glaucoma and accounts for about 90% of all cases. Glaucoma is one of the leading causes of blindness in people over 60. Glaucoma may have no symptoms in its early stages, and 50% of people with the disease don’t even know they have it.5 POAG may have no symptoms other than a slow loss of peripheral or central vision.

Other contributing factors for glaucoma can be family history, age, race, eye damage, and medical conditions.6 High-risk periodontal pathogens are not the only areas of concern. Untreated tooth decay, failing dental restorations that harbor bacteria, and abscesses can contribute to orbital cellulitis, an infection of the tissues around the eye (Figure 2). It can be a dangerous condition as infections travel from the oral cavity into the sinuses and migrate to the brain via the optic nerve. Orbital cellulitis provides a pathway for infection leading to brain abscesses, vision loss and/or death.7

The theory that oral bacteria enter the bloodstream and travel to other parts of the body, with the potential to create systemic inflammation, has been discussed since the late 1800s.8 Now we know that harmful oral pathogens have been linked to a wide range of conditions, including diabetes, obesity, certain cancers, cardiovascular disease and more.

Dental hygienists can be empowered to play a key role in health coaching for optimal oral and eye health. Here are some key strategies that can be incorporated into routine dental visits:

  • Ask on and encourage routine eye exams when reviewing medical history, including social and family history.
  • raise awareness by discussing the different mouth-systemic connections, including the mouth-eye connection.
  • Assess oral health at every visit. Prevention of oral infections and eye diseases is ideal. If they are not prevented, early detection is essential.
  • Promote healthy lifestyle to reduce risk, including smoking cessation, nutrition counseling, breathing, weight management, and sun protection for the head, neck, lips, and eyes.9
  • To bring effectively remove biofilm during professional cleanings and consider the use of lasers,ten ultrasound,11 and biofilm-guided therapy.12
  • Recommend evidence-based biofilm removal techniques for home care, such as WaterPik13 and PerioProtect trays.14

Dental hygienists are essential primary care providers who are highly qualified to provide training in emerging oral-systemic linkages. An altered oral microbiota can not only affect teeth and gums, but also vision and eye health.


Editor’s note: This article appeared in the April 2022 print edition of HDR magazine. Dental hygienists in North America are eligible for a free print subscription. Register here.


The references

  1. St. Leger T. Meet the eye microbiome. American scientist. June 23, 2019. Accessed January 31, 2022. https://www.scientificamerican.com/article/meet-the-eye-microbiome/
  2. Napolitano P, Filippelli M, Davinelli S, Bartollino S, dell’Omo R, Costagliola C. Influence of gut microbiota on eye disease: an overview. Anne-Med. 2021;53(1):750-761. doi:10.1080/07853890.2021.1925150
  3. Polla D, Astafurov K, Hawy E, Hyman L, Hou W, Danias J. A pilot study to assess oral microbiome and dental health in primary open-angle glaucoma. J Glaucoma. 2017;26(4):320-327. doi:10.1097/IJG.0000000000000465
  4. Coggins K, Husain A, Parsegian K, Whitson JT. Association between poor oral health and the risk of glaucoma. Invest Ophthalmol Vis Sci. 2021;62(8):1605.
  5. Glaucoma. Symptoms and causes. Mayo Clinic. Accessed January 15, 2022. https://www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839
  6. Glaucoma. Eyes and vision conditions. American Optometric Association. Accessed January 10, 2022. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/glaucoma
  7. Baiu I, Melendez E. Periorbital and orbital cellulitis. JAMA. 2020;323(2):196. doi:10.1001/jama.2019.18211
  8. Akshata KR, Ranganath V, Nichani AS. Thesis, antithesis and synthesis in periodontal and systemic interdependence. J Indian Soc Periodontol. 2012;16(2):168-173. doi:10.4103/0972-124X.99257
  9. Tips to prevent vision loss. Centers for Control and Prevention of Disasters. Revised August 10, 2021. Accessed January 31, 2022. https://www.cdc.gov/visionhealth/risk/tips.htm
  10. Convisar RA. Principles and Practice of Laser Dentistry. Mosby; 2011.
  11. Vyas N, Wang QX, Manmi KA, Sammons RL, Kuehne SA, Walmsley AD. How does ultrasonic cavitation remove dental bacterial biofilm? Sonochem Ultrasound. 2020;67:105112. doi:10.1016/j.ultsonch.2020.105112
  12. Drago L, Del Fabbro M, Bortolin M, Vassena C, De Vecchi E, Taschieri S. Biofilm removal and antimicrobial activity of two different air polishing powders: an in vitro study. J Periodontol. 2014;85(11):e363-e369. doi:10.1902/jop.2014.140134
  13. Gorur A, Lyle DM, Schaudinn C, Costerton JW. Removal of biofilm with a dental water jet. Compend Contin Educ Tooth. 2009;30(Specification No. 1):1-6.
  14. Keller D. How to manage oral biofilm using PerioProtect as a minimally invasive method for lasting oral health. Dental Products Report. 2010;44(7):54-55. Accessed January 31, 2022. https://providers.perioprotect.com/wp-content/uploads/2020/01/DPRO-HowToManage-Perio.pdf

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