Age-related macular degeneration

Some very recent research studies have investigated the link between periodontal pathogens and the eyesight disorder of age-related macular degeneration (AMD). “Age-related macular degeneration is one of the leading causes of irreversible vision loss in the elderly population. Although the exact pathophysiology of AMD is not fully understood, age-associated changes and oxidative stress, resulting in cellular damage, have been suggested as the triggering factors in AMD. This cellular damage is further aggravated by the subsequent immune and inflammatory response.”1

A Harvard School of Public Health study note, “Age-related macular degeneration (AMD) is the leading cause of blindness among older persons in the US and other developed countries. About 9 million adults aged 40 years or older in the US are affected by different forms and severity of AMD, and the number of persons having AMD is projected to double by 2020 owing to the rapidly aging population. AMD is categorized into early- and late-stage AMD according to AMD signs and severity. Most visual loss occurs in late AMD…”2

Many research studies has shown the connection of AMD and cardiovascular disease, which has shown to cause many systemic problems with atherosclerosis and arteriosclerosis and “clogging of arteries.” “Cardiovascular disease(CVD), which includes both coronary heart disease (CHD) and cerebrovascular disease (stroke), remains the leading cause of deaths in both men and women globally.”2

“While we have been aware of an association between periodontal disease and cardiovascular disease for quite some time, we are only now starting to discover and understand the relationship between periodontal disease and AMD.”1 A great deal of the connections between periodontal disease and cardiovascular disease and age-related macular degeneration are all linked with the “inflammation” process and the chemical markers.

“C-reactive protein is an acute-phase reactant protein used as a clinical biomarker for inflammation. Previous reports have already demonstrated increased levels of CRP in patients with periodontal disease. Increased levels of CRP have also been associated with an increased risk of developing AMD, providing support for an inflammatory component behind the pathogenesis of AMD.”1

In a very large research project in Korea, Yong and others did a large cross-sectional study that looked at over 13,000 adults over 40 yrs. old that had gradable retinal fundus photos.3 After dividing them into age groups 40-61 and over 61 age groups, they looked at the periodontal disease (PD) values and AMD amounts. In the whole group, PD was found in 37.4% and the AMD was found in 5.6%. They did a regression analysis to evaluate how the two were related. They found that there was not a significant association with those with mild perio and AMD, but there was an association between those with severe perio and AMD and mostly in those that were in the younger group. It was stated in the study that “participants with severe PD in the middle age group were 1.61 times more likely to have AMD.” “Our data, collected from an Asian population, showed that only severe PD is independently associated with AMD in individuals aged 62 years or younger.”3

Another study that was recently shown in a poster presentation by a predoctoral dental student, Hong, looked at how the bacteria from periodontal disease and AMD are connected. “The keystone oral-pathobiont and one of the major causative organism for [Chronic Perio] CP, Porphyromonas gingivalis (Pg), has been identified with the ability to invade epithelial, fibroblasts and dendritic cells.”4 “Our study was designed with an objective to interrogate the role of Pg and its fimbriae-mediated infection of human retinal-pigment epithelial cells and retro-orbitally injected mice retina, thus revealing possible molecular links between CP and AMD,” said Hyun Hong, the predoctoral dental student at Dental College of Georgia.

I think that it is amazing how the more we dig and look at different disease processes that so many things can be connected in ways we didn’t really think of. We also have to look at the main disease process, such as cardiovascular disease (CD), that affects so many parts of our body. With periodontal disease being in that loop, it makes sense that the other diseases that affected by CD could also be linked with periodontal disease too.

It also makes me think that we need to do a more detailed look at our medical history review that we go over with our patients each day. Rather than just asking our patients about “any changes in your medical history since last time?” we need to be re-looking over their history with a fine toothed comb!

References

1. Wagley S, Marra KV, Salhi RA, Gautam S, Campo R, Veale P, Veale J, Arroyo JG. Periodontal disease and age-related macular degeneration: Results From the National Health and Nutrition Examination Survey III. Retina. 2015 May;35(5):982-8. doi: 10.1097/IAE.0000000000000427.

2. Juan Wu, Age-Related Macular Degeneration and the Incidence of Cardiovascular Disease: A Systematic Review and Meta-Analysis. Affiliation Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America. Published: March 28, 2014, https://doi.org/10.1371/journal.pone.0089600. E-mail: [email protected].

3. Yong US, Han WL, Eun HH, Min HK, Mincheol S, Eunwoo N, Heeyoon C, National Institutes of HealthJournal ListMedicine (Baltimore),v.96(14); 2017 Apr., PMC5411190. Published online 2017 Apr 7. doi: 10.1097/MD.0000000000006418, PMCID: PMC5411190, PMID: 28383406 Received 2016 Aug 15; Revised 2017 Feb 24; Accepted 2017 Feb 27.

4. Hong H. Investigating the enigmatic link between periodontal inflammation and retinal degeneration. Public release: March 23, 2018. International & American Associations for Dental Research, http://www.dentalresearch.org

5. Wagley S, Arroyo JG. Periodontal Disease and AMD: While perhaps surprising, recent research has indicated a link between gum disease and AMD. May 1, 2015,

Retinal Physician, Volume: 12, Issue: May 2015, page(s): 58-60.