Diabetes and Eyes: How Diabetes Affects Your Sight
Over the years, diabetes silently damages the small blood vessels in the retina. This guide covers the stages of diabetic retinopathy, from leakage to bleeding, plus symptoms, prevention and treatment.
Over the years, diabetes damages the walls of the small blood vessels in the retina. First, the vessels leak, and fluid can collect in the macula. Then some vessels close off, so the retina loses its blood supply. In advanced stages, fragile new vessels grow. They can bleed into the eye and pull on the retina. However, these changes often cause no symptoms for a long time. Therefore, blood sugar and blood pressure control and regular eye exams are the best protection. Treatment includes laser, eye injections and surgery.
How does diabetes damage your eyes?
The retina is a thin layer of nerve tissue that lines the back of the eye and senses images. Many small blood vessels feed it. Blood sugar that stays high for a long time harms the cells in the walls of these vessels. A garden hose is a good comparison. If its wall weakens, it first leaks and then clogs. As a result, the areas that get no water dry out.
“In diabetes, the cells in the vessel wall are damaged first, and leakage begins. Then the vessels close off. The retina, which can no longer be nourished, produces new vessels. These bleed easily and can pull on the retina.”
— Prof. Dr. Fırat Helvacıoğlu, from the video
What can diabetes do to the eyes?
Prof. Dr. Fırat Helvacıoğlu explains how diabetes affects the eyes and how it is treated.
How does diabetes affect the retinal vessels step by step?
Over the years, high blood sugar damages the walls of the small retinal vessels. First comes leakage, then blockage. Finally, new vessels that bleed easily develop.
- Healthy vesselThe supporting cells in the vessel wall (pericytes) and the inner lining cells are intact. Blood does not leak out.
- LeakageWhen the wall weakens, fluid and fatty deposits leak into the retina. Fluid that collects in the macula (macular edema) blurs vision.
- BlockageSome small vessels close off. As a result, areas of the retina receive no blood supply.
- New vessels and bleedingThe retina without blood supply grows new vessels. They are fragile, so they can bleed into the eye and pull on the retina.
Which eye symptoms of diabetes need attention?
Diabetic retinopathy often causes no symptoms until an advanced stage. For this reason, you need regular dilated eye exams even if your vision is good. However, the following symptoms need an exam without delay:
Do not wait to be seen
- Blurred vision, especially in the center
- Floaters that suddenly increase, soot-like spots or a curtain over your vision
- Straight lines that look bent
- Vision that changes noticeably during the day
I explained what bleeding inside the eye means in the article “Is an eye bleed dangerous?”
How to protect your eyes: control and exams
Worldwide, an estimated 93 million people have diabetic retinopathy. About 28 million of them have a vision-threatening stage. The same study found that long diabetes duration, poor blood sugar control and high blood pressure are the strongest risk factors.
- Keep your blood sugar (HbA1c) at the target your doctor sets.
- Also watch your blood pressure and cholesterol, and quit smoking.
- In type 2 diabetes, start dilated eye exams at diagnosis. In type 1 diabetes, start a few years after diagnosis. Usually, repeat them once a year.
- If you have diabetes during pregnancy, eye exams are done more often.
Treatment options for diabetes and eyes
| Treatment | When? |
|---|---|
| Laser treatment | To prevent new vessels in areas of the retina without blood supply, and to seal leaking spots |
| Eye injection (anti-VEGF, cortisone) | Fluid in the macula (macular edema) and growth of new vessels |
| Vitrectomy surgery | Bleeding inside the eye that does not clear, membranes pulling on the retina, or retinal detachment |
Laser treatment is effective at preventing vision loss. However, it can restore lost vision only to a limited extent, so early treatment matters. Eye injections can improve vision in macular edema. For details, see our diabetic retinopathy page.
Other effects of diabetes on the eyes
- Changing glasses prescription: When blood sugar changes quickly, the lens of the eye swells and shrinks. This can change your prescription temporarily. Therefore, wait until your blood sugar is stable before getting new glasses.
- Cataract: It can appear earlier in people with diabetes.
- Dry eye and corneal problems: When the corneal nerves are affected, surface healing can slow down.
- Glaucoma: In advanced retinopathy, new vessels can raise the eye pressure.
Frequently asked questions
A dilated eye exam once a year is generally recommended. If retinopathy is found, check-ups are more frequent.
In the early stage, controlling blood sugar and blood pressure can slow progression. In advanced stages, treatment aims to protect vision. Damage that has already occurred does not always reverse.
The eye is numbed with drops, and the procedure takes a few minutes. Most patients feel only mild pressure.
Yes. Diabetic retinopathy may cause no symptoms until an advanced stage. Changes caught early are much easier to treat.
Yes. Before surgery, we assess the retina, especially the macula. If needed, the retina is treated first.
Related pages
References
- Yau JW, Rogers SL, Kawasaki R, et al. Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care. 2012;35(3):556-564. doi:10.2337/dc11-1909
- Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet. 2010;376(9735):124-136. doi:10.1016/S0140-6736(09)62124-3
This article is for patient information only. It does not replace an examination or medical assessment. The treatment that suits you is decided after your eye exam and measurements. Publication date: 25 September 2026.
Contact Prof. Dr. Fırat Helvacıoğlu with your questions
Prof. Dr. Fırat Helvacıoğlu · Veni Vidi Eye Clinic, Bağdat Cad. No: 257, Caddebostan – Kadıköy / Istanbul