Diabetic Retinopathy

Created: Nov 2021


Worldwide, the prevalence rate of diabetic retinopathy (DR) in people with diabetes was estimated to be 34.6%, and the rate of vision-threatening diabetic retinopathy (VTDR) was 10.2%. American National Health and Nutrition Examination Survey showed that 28.5% of people with diabetes had some DR symptoms, and 4.4% had some VTDR symptoms. Other developed countries also exhibit similar prevalence rates.

Another, more recent study, put the prevalence of DR at 22.27% and of VTDR at 6.17% for individuals with diabetes.


The underlying cause of DR is believed to be prolonged high blood sugar resulting from diabetes. This damages the retina and leads to DR development. Diabetes can harm blood vessels all over the body, including the vessels connected to the retina. Sugar can block those vessels, prompting them to leak fluid or bleed. The eye can grow new blood vessels to make up for the blocked ones, but the process is imperfect, and the new vessels can also leak or bleed, which damages the retina further. Overall, the damage to the vessels can cause haemorrhages and swelling of the retina, and it can suffer from oxygen deficiency.


DR is characterized by vascular abnormalities in the retina. In the first stage of DR, called non-proliferative diabetic retinopathy (NPDR), vascular permeability and capillary occlusion of the retina increase. Blood vessels dilate, blood flow changes, pericyte levels decrease, and inflammation occurs. Retinal pathologies such as microaneurysms and hemorrhages can be found.

In the second stage, called proliferative diabetic retinopathy (PDR), expression levels of VEGF (angiogenic factor) increase and neovascularization (forming new vessels) is common.

Vision loss in DR patients often occurs due to diabetic macular edema (DME), which is characterized by swelling or thickening of the macula, which is part of the retina located on the back of the eyeball.


In the NPDR stage, patients often do not suffer from any symptoms. Slight, temporary impairments such as trouble reading or seeing faraway objects may occur.

In the PDR stage, several vision impairments are observed, which is caused by the newly formed, abnormal vessels bleeding into the vitreous in the eyeball. The patients might notice dark, floating spots or streaks which might disappear after a while. Blurred vision (due to DME), double vision and eye pain are also common.


DR can be treated differently depending on disease stage. In the early stage, though there is no direct treatment, frequent eye checks, including dilated eye exams, are necessary.

After DR progresses, treatment with eye injections of anti-VEGF medicine can be used to slow down or reverse DR. Corticosteroids are also used. Controlling blood sugar, blood pressure and cholesterol is recommended.

Laser surgery is another common form of treatment. Though it will not improve the patient's vision, it can prevent the symptom aggravation. Laser bursts can repair vessel leaks, reduce swelling and facilitate the oxygen and nutrient supply. PDR is treated with laser scattering over the whole retina to shrink abnormal and damaged vessels and prevent new ones from forming. Graver DR can be addressed by a type of eye surgery called vitrectomy, which removes blood from the vitreous and scar tissue from the retina.


Zheng, Y., He, M., & Congdon, N. (2012). The worldwide epidemic of diabetic retinopathy. Indian journal of ophthalmology, 60(5), 428–431. https://doi.org/10.4103/0301-4738.100542

Teo, Z. L., Tham, Y. C., Yu, M., Chee, M. L., Rim, T. H., Cheung, N., Bikbov, M. M., Wang, Y. X., Tang, Y., Lu, Y., Wong, I. Y., Ting, D., Tan, G., Jonas, J. B., Sabanayagam, C., Wong, T. Y., & Cheng, C. Y. (2021). Global Prevalence of Diabetic Retinopathy and Projection of Burden through 2045: Systematic Review and Meta-analysis. Ophthalmology, S0161-6420(21)00321-3. Advance online publication. https://doi.org/10.1016/j.ophtha.2021.04.027

NIH National Eye Institute. 2019. Diabetic Retinopathy. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/diabetic-retinopath. Accessed 13th Jun 2021

Diabetes.co.uk. 2019. Diabetic Retinopathy. https://www.diabetes.co.uk/diabetes-complications/diabetic-retinopathy.html Accessed 13th Jun 2021

Wang, W., & Lo, A. (2018). Diabetic Retinopathy: Pathophysiology and Treatments. International journal of molecular sciences, 19(6), 1816. https://doi.org/10.3390/ijms19061816

Patty Onderko. 2020. Let's Talk About Diabetic Retinopathy. https://www.healthcentral.com/condition/diabetic-retinopathy Accessed 13th Jun 2021