It is well known that hyperglycemia associated with diabetes is dangerous to many cells throughout the whole body. One such area of the body effected by diabetes is the eye. In fact, diabetic retinopathy (DR), or disease of the retina, is the leading cause of blindness in people over the age of 50 (Lutty, 2013).
The development of DR starts in response to hyperglycemia. Autoregulated responses of retinal blood vessels to increased blood sugar first lead to microaneurysms and pericyte loss (Wang & Lo, 2018). Pericytes are cells that provide support for retinal capillaries, so you can see how losing them would have negative consequences for the eye. Next, a pathway of inflammation is activated by leukostasis, in which white blood cells stick and accumulate, forming plugs in retinal blood vessels (Wang & Lo, 2018). In diabetic patients, leukostasis is driven by the upregulation of chemokines (which attract and activate leukocytes) and leukocyte adhesion molecules (Lutty, 2013). All these effects on retinal vasculature further damage the endothelial cells of the retina, leading vascular leakage. A “leaky” vasculature greatly increases the chance of diabetic macular edema, which ultimately causes visual function loss in diabetic patients (Lutty, 2013).
While DR is mostly considered a microvascular disease, there is also evidence that diabetes influences retinal neurons, also leading to diabetic retinopathy. High glucose levels have been shown to induce mitochondrial dysfunction and apoptosis in retinal neurons (Tien et al., 2017). Damaging retinal neurons, and thus damaging the eye’s ability to transmit signals to the brain will no doubt influence one’s ability to see/process images.
Early detection of symptoms of diabetic retinopathy is crucial for further treatment and prevention of blindness in diabetic patients. Annual eye exams are important for everyone, but they are of utmost importance for patients with diabetes (which is why your optometrist may recommend an exam every 6 or 3 months)!
References
Lutty, G. A. (2013). Effects of diabetes on the eye. Investigative ophthalmology & visual science, 54(14), ORSF81-ORSF87.
Tien, T., Zhang, J., Muto, T., Kim, D., Sarthy, V. P., & Roy, S. (2017). High Glucose Induces Mitochondrial Dysfunction in Retinal Müller Cells: Implications for Diabetic Retinopathy. Investigative ophthalmology & visual science, 58(7), 2915–2921.
Wang, W., & Lo, A. C. (2018). Diabetic retinopathy: pathophysiology and treatments. International journal of molecular sciences, 19(6), 1816.
I was looking into the chances of diabetic macular edema and found that part of treatment is getting the right dosage and timing of drugs. I found a study to test the safety and surgical feasibility of the implantation of Posterior MicroPump (PMP) Drug Delivery in DME patients (Hemayun 2014). They implanted PMP prefilled with ranibizumab, then this device is controlled by a programmed microdose. Along these biweekly eye exams (Hemayun 2014). This study has it’s dangers but overall they had really positive success rates, their were minor complications but nothing without a simple solution, so I think this could be a good viable option for diabetic macular edema patients.
ReplyDeleteHumayun, M., Santos, A., Altamirano, J. C., Ribeiro, R., Gonzalez, R., de la Rosa, A., Shih, J., Pang, C., Jiang, F., Calvillo, P., Huculak, J., Zimmerman, J., & Caffey, S. (2014). Implantable MicroPump for Drug Delivery in Patients with Diabetic Macular Edema. Translational vision science & technology, 3(6), 5. https://doi.org/10.1167/tvst.3.6.5
Great job Kaylee! I have heard about diabetic retinopathy before, but I did not really know how it came to be and the mechanisms behind it. After reading what you wrote I was wondering what ways there are to prevent getting and/or worsening diabetic retinopathy, or is it just a game of chance for those who have diabetes? According to an article published in the Journal of Diabetes Investigation (JDI) there are certain risk factors that increase your chances of developing this and ways in which to reverse these risks (Lin et al., 2021). It was found that hypertension, nephropathy, dyslipidemia, smoking, and higher body mass index are all factors that increase one's risk for developing this disease (Lin et al., 2021). Although, there are ways to reverse each of these through changes in lifestyle which will allow a person to have a lesser chance of developing diabetic retinopathy (Lin et al., 2021). Knowing this, as well as lots of other medical facts, it can be seen that managing a healthy lifestyle is important in avoiding disease.
ReplyDeleteLin, K. Y., Hsih, W. H., Lin, Y. B., Wen, C. Y., & Chang, T. J. (2021). Update in the epidemiology, risk factors, screening, and treatment of diabetic retinopathy. Journal of diabetes investigation, 12(8), 1322–1325. https://doi-org.dml.regis.edu/10.1111/jdi.13480
Nice blog Kaylee. Reading this blog spurred me to go and do some further research on retinopathy and something quite interesting. As it turns out there can be a forms of non-diabetic retinopathy and it should be important for physicians to understand the potential causes of this ailment in patients who are not diabetic. An NIH website has a full list of etiologies of patients who have retinopathy, one of those being sickle cell anemia. This makes sense due to the fibrinogens that are produced by the sickled cells can cause the microaneurysms in the eyes similar that of diabetic retinopathy.
ReplyDeletehttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC381138/