- Researchers investigated the effects of multiple medications on the prevalence of age-related macular degeneration (AMD).
- The findings show that lipid-lowering drugs and anti-diabetic drugs are linked to lower AMD prevalence.
- The study authors noted that further research is needed to confirm their results and understand the underlying mechanisms.
Age-related macular degeneration (AMD) is an eye condition characterized by deterioration of the central field of vision. According to the National Eye Institute, AMD is the leading cause of blindness in older adults and typically affects those ages 55 and older.
Multiple factors may affect AMD risk, including genetic and environmental risk factors. Factors that may increase risk include smoking, a sedentary lifestyle, and chronic inflammation.
Despite decades of research, no medical treatments exist to prevent AMD and limited methods available to slow its progression.
Studies have examined how various drugs, such as lipid-lowering drugs (LLD)s like statins, nonsteroidal anti-inflammatory drugs (NSAIDs), and antidiabetic drugs, affect the development of AMD.
Results from these studies, however, have been inconsistent. It thus remains unclear as to whether these drugs are linked to the risk of AMD.
In a new study, researchers conducted a meta-analysis of studies examining the links between various medications and AMD. They found that LLDs and antidiabetic drugs are linked to a lower prevalence of AMD.
Dr. Howard R. Krauss, surgical neuro-ophthalmologist and director of Pacific Neuroscience Institute’s Eye, Ear & Skull Base Center at Providence Saint John’s Health Center in Santa Monica, CA, not involved in the study, told Medical News Today:
“The implications of these findings are that there may be pharmaceuticals, supplements, or lifestyle changes, beyond those already determined (such as smoking cessation) which will [delay] the onset and progression of AMD. In particular, LLDs and diabetes drugs are candidates worthy of further study.”
The study was recently published in the British Journal of Ophthalmology.
Linking medications to age-related macular degeneration
For the study, the researchers analyzed 14 studies that included data on systemic medication use and AMD in various European countries, including:
- France
- Germany
- Greece
- Ireland
- Italy
- Norway
- Portugal
- Russia
- United Kingdom
Altogether, they included records from 38,694 patients. Between the 14 included studies, the average age ranged from 61.5 to 82.6 years old. Overall, the researchers recorded 9,332 and 951 cases of any and late AMD, respectively.
After analyzing the data, they found that LLDs and antidiabetic drugs were linked to 15% and 22% lower AMD prevalence.
However, the researchers noted that they found no associations with late AMD or with other medication types. They wrote that this may have arisen due to a lack of statistical power.
How cholesterol and diabetes drugs lower AMD risk
When asked how cholesterol and diabetes drugs might lower AMD risk, Dr. Philip Storey, board certified ophthalmologist and affiliate faculty member at the University of Texas Dell Medical School, not involved in the study, told MNT:
“We don’t yet know how cholesterol or diabetic drugs might lower AMD risk, but we can hypothesize based on our current understanding of the disease.”
Dr. Matthias M. Mauschitz, Ph.D., a professor at the University of Bonn, and the study’s lead author, agreed that the exact mechanisms remain unknown.
“Given that drusen, which represents one of the hallmark lesions of AMD, consists of metabolic debris including lipids, lipid metabolism has been hypothesized to deteriorate in AMD,” Dr. Mauschitz said.
“Various studies reported high oxidative stress and an increased general inflammation to result in a breakdown of specific cell functions in the retina, which may contribute to AMD development. LLD interferes [with] lipid metabolism by reducing blood levels of certain metabolites such as low-density lipoprotein (LDL) and cholesterol. Both LLD and antidiabetic drugs, particularly metformin, have been reported to exhibit anti-inflammatory effects and reduce oxidative stress.”
– Dr. Matthias Mauschitz, Ph.D., lead author of the study
Dr. Krauss added that AMD has a significant metabolic component to the disease.
“The retina is a metabolically active tissue, so it is not a stretch to think that other diseases that affect our cardiovascular system would also affect a tissue like the retina,” he said.
“Both high cholesterol and high blood sugar can have negative metabolic effects. Thus, treating these conditions with medications that lower cholesterol and lower blood sugar should help the entire body, including the retina. Some of these medications have also been shown to have their own anti-inflammatory effects, which further help to protect the body, and the retina, from damage.”
The researchers concluded that their findings underscore the importance of metabolic processes in understanding the causes of AMD.
Limitations of new AMD research
The researchers highlighted some limitations to their findings.
Dr. Mauschitz noted that their study was cross-sectional, so it cannot infer causality.
He also said that their results might underestimate certain associations due to a potential selection bias (i.e., survival bias) of healthy participants, as those in worse general health may have died before enrolment.
The researchers further noted that as their study predominantly included Caucasian people, their findings might not apply to more diverse populations.
Implications for future AMD research
“The findings in the study serve to support the fact that taking care of the rest of the body will also help care for the health of the eyes,” Dr. Benjamin Bert, an ophthalmologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, not involved in the study, told MNT.
“Lowering blood sugar protects any organs that have microvasculature — kidneys, brain, and eyes. Lowering cholesterol helps to protect against cardiovascular disease.”
“This study helps to show that treating these two conditions, in particular, also has a positive outcome on the development of AMD. Thus, it is important to have your annual eye exam and your routine physical exam, including blood tests, so that necessary treatment can be initiated appropriately.”
– Dr. Benjamin Bert, ophthalmologist
Dr. Mauschitz added that the findings might impact European public health issues, given the high frequency of LLD and antidiabetic use on the continent.
“Our data can contribute to a better understanding of AMD etiology, but further longitudinal studies ought to evaluate the relation of specific drug types with AMD occurrence,” Dr. Mauschitz concluded.
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