Diabetic retinopathy is damage to the small blood vessels that supply the retina as a result of prolonged high blood glucose. It can begin silently, while regular screening can detect small hemorrhages, leakage, or swelling of the macula before permanent visual loss develops.
Article Contents
Key Message
Clear vision does not always mean the retina is healthy. Early changes can be present without symptoms, so screening should not depend on symptoms alone.
Risk Factors
- Longer duration of diabetes.
- High or fluctuating HbA1c/blood glucose.
- High blood pressure or abnormal lipids.
- Kidney disease and smoking.
- Pregnancy in a patient with pre-existing diabetes.
1. What Is Diabetic Retinopathy?
Damage to the Small Blood Vessels of the Retina
The retina is a thin neural layer lining the back of the eye that converts light into signals sent to the brain. When blood glucose remains elevated for a long time, small retinal vessels can weaken, causing microaneurysms, hemorrhage, and leakage of fluid or lipids.
If leakage reaches the macula, the area responsible for detailed central vision such as reading and recognizing faces, diabetic macular edema may occur. In advanced disease, fragile new vessels may grow, bleed into the eye, or cause traction and retinal detachment.
Yes. Retinal screening is important for all people with diabetes even when vision is excellent, because early retinal changes may not affect vision. Screening allows changes to be identified and managed before they cause visual loss.
2. When Should a Person with Diabetes Have Retinal Screening?
A Simple Guide to the First Examination and Follow-up
The following provides a general guide. An ophthalmologist may recommend earlier review when retinopathy is already present, during pregnancy, when diabetes is poorly controlled, with kidney disease or hypertension, or when new symptoms appear.
Type 1 Diabetes
Retinal screening generally begins after a period of time following diagnosis.
Type 2 Diabetes
Screening should not be delayed because type 2 diabetes may have been present for years before diagnosis.
Pregnancy with Pre-existing Diabetes
Early retinal assessment and individualized follow-up are important during pregnancy.
Existing Retinopathy or Macular Edema
Follow-up timing depends on the degree of retinal change and whether treatment is required.
Sudden Symptoms
Require urgent assessment rather than waiting for routine follow-up.
The doctor may determine that annual screening is not sufficient and recommend earlier review in situations such as:
- Markedly elevated HbA1c or prolonged poor glucose control.
- Other conditions that may increase retinal risk, such as hypertension, kidney disease, or abnormal lipids.
- After cataract surgery, when retinal status may require closer follow-up before or after the operation.
- Retinal changes associated with unstable blood glucose levels.
The ophthalmologist determines the appropriate follow-up interval based on examination findings, retinopathy severity, and individual risk factors.
3. Which Tests Are Used to Assess the Retina?
Dilated Fundus Examination
This is a standard method of examining the retina. Dilating drops require time to take effect and can blur near vision and increase light sensitivity for several hours. Driving should be avoided until vision has returned to a safe, comfortable level.
Color or Ultra-Widefield Retinal Photography
Ultra-widefield imaging can document a large area of the retina quickly and may reduce the need for dilation in selected situations. Whether dilation is still needed depends on the clinical examination and image quality.
Optical Coherence Tomography (OCT)
OCT provides detailed cross-sectional imaging of the macula. It helps detect macular edema, measure retinal thickness, and monitor response to intravitreal treatment.
Fluorescein Angiography When Needed
A dye is injected into a vein and serial images are taken to identify leakage, areas of reduced perfusion, or abnormal new vessels. It is not required for every patient.
Widefield OCT Angiography (OCTA) Without Dye
OCTA displays the retinal vascular network without intravenous dye. Widefield OCTA can help identify areas of reduced blood flow and vascular abnormality. Whether fluorescein angiography is still needed depends on the clinical question and imaging findings.
Other Tests the Doctor May Request
- Visual acuity and eye-pressure measurement.
- Examination of the anterior segment and natural lens to assess cataract or other causes of blurred vision.
- Ocular ultrasound when hemorrhage prevents direct visualization of the retina.
4. Stages of Diabetic Retinopathy
Mild Non-Proliferative
Small vascular changes such as microaneurysms may be present without symptoms.
Moderate Non-Proliferative
More hemorrhage or leakage with increasing vascular abnormalities.
Severe Non-Proliferative
More extensive retinal ischemia with a higher risk of progression to proliferative disease.
Proliferative Diabetic Retinopathy
Fragile new vessels may bleed or cause traction and retinal detachment.
Diabetic Macular Edema
Diabetic macular edema is not a separate fifth stage. It can occur at any stage of diabetic retinopathy and may be the main cause of central blur, reading difficulty, or distorted lines even when the rest of the retina is not in the most advanced stage.
5. Symptoms That May Appear as Disease Progresses
Gradual Symptoms
- Blurred or fluctuating vision.
- Difficulty reading or seeing fine detail.
- Reduced night vision.
- Reduced color clarity or distorted lines.
Sudden Symptoms
- Sudden increase in floaters or black spots.
- Dense haze or sudden vision loss.
- Flashes of light or a curtain-like shadow.
- Loss of part of the visual field.
Symptoms can mean that the macula or vitreous has already become involved. The purpose of regular screening is to detect disease before this stage.
6. Treatment of Diabetic Retinopathy
1. Control Diabetes, Blood Pressure and Lipids
This is the foundation of prevention and slowing progression. It includes following the diabetes-management plan, monitoring HbA1c, controlling blood pressure and cholesterol, treating kidney disease, and avoiding smoking.
2. Intravitreal Injections
Anti-VEGF medications are commonly used for diabetic macular edema or abnormal new vessels. A series of injections may be required, followed by monitoring with retinal imaging and OCT.
3. Laser Treatment
Panretinal laser may be used to reduce the risk of bleeding and complications in proliferative retinopathy, while focal laser may be used in selected situations. The goal is often to protect vision and reduce further deterioration.
4. Vitreoretinal Surgery
Surgery may be necessary for persistent vitreous hemorrhage, tractional retinal detachment, or advanced complications not adequately managed with injections or laser alone.
Treatment is selected according to the location of retinal changes, the presence of macular edema, degree of ischemia, retinopathy stage, visual acuity, and general health.
7. How Are Intravitreal Injections Performed?
A Short Procedure Under Local Anesthesia
- Clean the skin and eyelids and disinfect the ocular surface.
- Apply topical anesthetic drops to reduce discomfort.
- Use a sterile eyelid speculum and inject the medication into the vitreous cavity.
- Examine the eye and provide post-injection instructions.
A mild gritty sensation or a small surface blood spot can occur. Severe pain, increasing redness, or worsening vision requires urgent contact with the doctor to exclude intraocular infection.
8. How Can a Person with Diabetes Protect the Retina?
- Attend scheduled eye examinations even when there are no symptoms.
- Work with the diabetes team to reach appropriate glucose targets.
- Monitor and treat high blood pressure.
- Control cholesterol and other lipids.
- Stop smoking and maintain appropriate physical activity.
- Inform the ophthalmologist about pregnancy or plans for pregnancy.
- Do not stop injections, laser treatment, or follow-up simply because vision improves.
- Seek urgent assessment for any sudden visual change.
9. When Should You See an Ophthalmologist Immediately?
- Sudden or severe vision loss.
- Sudden increase in floaters or many new black spots.
- Repeated flashes of light.
- A curtain or shadow covering part of the visual field.
- Severe blurred vision after an injection, especially with pain and redness.
10. Frequently Asked Questions About Diabetes and Retinal Screening
Is Retinal Screening Painful?
The examination is usually not painful. Dilating drops can briefly sting and may cause temporary near blur and light sensitivity for several hours.
Can I Drive After Pupil Dilation?
Near vision and bright light may be uncomfortable temporarily. Arrange transportation or avoid driving if vision is not comfortable or clear after dilation.
Does a Normal Retinal Photograph Mean I Do Not Need Future Screening?
No. A normal image is reassuring, but retinal changes can develop later. The next examination is determined by diabetes type, duration, control, and risk factors.
Is OCT Needed at Every Visit?
Not always. OCT is requested when the doctor needs to assess the macula, monitor diabetic macular edema, or evaluate treatment response.
Can Vision Improve After Treatment?
Vision can improve in some cases, especially when diabetic macular edema is treated early. In other cases, the primary goal is to stabilize vision and prevent further deterioration.
Summary
Retinal screening is an essential part of routine diabetes care and should not be performed only when vision becomes poor. Screening begins at diagnosis for type 2 diabetes and usually within five years of the onset of type 1 diabetes. Follow-up intervals then depend on retinal findings and risk factors. Retinal photography, OCT, OCTA, and other tests help determine disease stage and select appropriate follow-up or treatment at the right time.
Is It Time for Your Retinal Screening?
The retina can be assessed and the need for retinal photography, OCT, or OCTA determined, followed by a screening interval appropriate for the type of diabetes and retinal findings.