Author: Dr Val Phua
Estimated reading time: 8–10 minutes
Diabetes Can Affect Your Eyes Long Before You Notice Any Symptoms
Diabetes is one of the leading causes of preventable vision loss worldwide. While many people are aware that diabetes affects the heart, kidneys and nerves, fewer realise that it can also damage the delicate structures inside the eye.
One of the challenges of diabetic eye disease is that it often develops silently. Your vision may remain perfectly normal even while changes are occurring within the retina. By the time symptoms develop, significant and sometimes irreversible vision loss may already have occurred.
The good news is that most diabetes-related eye diseases can be detected early through regular comprehensive eye examinations and treated effectively before permanent damage occurs.
How Does Diabetes Affect the Eyes?
Persistently elevated blood glucose levels damage the small blood vessels throughout the body, including those that supply the retina—the light-sensitive tissue lining the back of the eye that converts light into visual signals.
Over time, these damaged blood vessels may:
- Leak blood or fluid
- Become blocked
- Cause retinal swelling
- Trigger the growth of abnormal new blood vessels
- Lead to permanent scarring if left untreated
Diabetes can also affect other parts of the eye, increasing the risk of cataracts, glaucoma and dry eye disease.
Common Eye Conditions Caused by Diabetes
Diabetic Retinopathy
Diabetic retinopathy is the most common diabetes-related eye disease and remains a leading cause of blindness among working-age adults.
In the early stages, tiny retinal blood vessels become weakened and begin leaking small amounts of blood or fluid.
As the disease progresses, blood vessels may close off completely, reducing oxygen supply to the retina. The eye then attempts to compensate by growing fragile new blood vessels—a condition known as proliferative diabetic retinopathy—which can bleed into the eye and cause retinal detachment.
Fortunately, early diabetic retinopathy often responds well to treatment when detected before vision is affected.
Diabetic Macular Oedema (DME)
The macula is the central part of the retina responsible for detailed vision needed for reading, driving and recognising faces.
When leaking blood vessels cause fluid to accumulate within the macula, vision becomes blurred or distorted.
Diabetic macular oedema is one of the most common causes of visual impairment in people with diabetes.
Cataracts
People with diabetes tend to develop cataracts at an earlier age compared with those without diabetes.
High blood sugar accelerates changes within the natural lens, causing it to become cloudy more rapidly.
Glaucoma
Diabetes is associated with an increased risk of glaucoma. In advanced diabetic eye disease, abnormal new blood vessels may block the normal drainage channels within the eye, resulting in a severe form known as neovascular glaucoma.
Dry Eye Disease
People living with diabetes commonly experience dry eyes due to reduced tear production and impaired corneal nerve function.
Symptoms may include:
- Burning
- Grittiness
- Fluctuating vision
- Excessive watering
- Contact lens intolerance
Who Is at Higher Risk?
Your risk of diabetic eye disease increases if you:
- Have had diabetes for many years
- Have poorly controlled blood sugar
- Have high blood pressure
- Have elevated cholesterol
- Smoke
- Have diabetic kidney disease
- Are pregnant with pre-existing diabetes
- Miss regular eye examinations
The longer diabetes is present, the greater the likelihood of developing diabetic retinopathy.
What Symptoms Should I Watch For?
One of the most important facts about diabetic eye disease is that there may be no symptoms at all during the early stages.
As disease progresses, symptoms may include:
- Blurred vision
- Fluctuating vision
- Difficulty reading
- Dark spots or floaters
- Distortion of straight lines
- Reduced colour vision
- Difficulty seeing at night
- Sudden loss of vision
Any sudden change in vision should be assessed promptly by an ophthalmologist.
How Often Should People with Diabetes Have Their Eyes Examined?
Regular retinal examinations are one of the most effective ways to prevent vision loss from diabetes.
In general:
Type 1 Diabetes
A comprehensive dilated eye examination should begin within five years of diagnosis, followed by annual reviews thereafter.
Type 2 Diabetes
Because type 2 diabetes may be present for several years before diagnosis, a comprehensive eye examination should be performed at the time of diagnosis, followed by annual reviews.
Pregnancy
Women with pre-existing diabetes should undergo an eye examination before pregnancy or during the first trimester, as diabetic retinopathy may worsen during pregnancy.
Some patients require more frequent reviews depending on the severity of retinal disease.
What Happens During a Diabetic Eye Examination?
A comprehensive diabetic eye assessment may include:
Vision Assessment
Measurement of visual acuity to monitor changes over time.
Dilated Retinal Examination
Special eye drops enlarge the pupils to allow careful examination of the retina and optic nerve.
Retinal Photography
High-resolution retinal photographs document diabetic changes and allow comparison over time.
Optical Coherence Tomography (OCT)
OCT produces detailed cross-sectional images of the retina, allowing detection of diabetic macular oedema that may not yet be visible clinically.
Additional Investigations
When required, your ophthalmologist may recommend:
- Fluorescein angiography
- OCT angiography
- Fundus autofluorescence
- Ultrasonography (if bleeding obscures the retina)
Can Diabetic Eye Disease Be Treated?
Yes.
Treatment depends on the stage and severity of disease.
Options include:
- Improved blood sugar control
- Optimisation of blood pressure and cholesterol
- Anti-VEGF injections for diabetic macular oedema
- Intravitreal steroid injections in selected cases
- Retinal laser treatment
- Vitrectomy surgery for advanced complications
Many patients maintain excellent vision when disease is detected and treated early.
How Can I Protect My Vision?
There are several important steps you can take:
- Maintain good blood sugar control (HbA1c as advised by your physician)
- Keep blood pressure under control
- Manage cholesterol levels
- Exercise regularly
- Eat a balanced diet
- Stop smoking
- Attend regular comprehensive eye examinations
- Follow treatment recommendations promptly
These measures reduce both the risk of developing diabetic eye disease and the likelihood of progression.
Frequently Asked Questions
My vision is normal. Do I still need yearly eye examinations?
Yes. Diabetic retinopathy frequently develops without affecting vision in its early stages. Regular examinations allow treatment before permanent damage occurs.
Can improving my blood sugar reverse diabetic retinopathy?
Good glucose control slows progression and reduces the risk of complications, but established retinal damage may not fully reverse. Early detection remains essential.
Can diabetic eye disease cause blindness?
Yes. If left untreated, diabetic retinopathy and diabetic macular oedema can lead to severe and permanent vision loss. Fortunately, modern treatments have significantly improved outcomes when disease is identified early.
Is diabetic retinopathy preventable?
Although not always completely preventable, maintaining good control of blood sugar, blood pressure and cholesterol, together with regular eye examinations, greatly reduces the risk of sight-threatening complications.
The Bottom Line
Diabetes can affect your eyes long before you notice any change in your vision. Regular comprehensive eye examinations remain the most effective way to detect diabetic eye disease early and preserve sight.
With modern imaging technologies and effective treatments—including retinal laser therapy, intravitreal injections and vitreoretinal surgery—most diabetes-related vision loss can be prevented when problems are identified promptly.
If you have diabetes, even if your vision appears perfectly normal, an annual comprehensive eye examination is one of the most important investments you can make in protecting your long-term eyesight.
References
- American Diabetes Association. Standards of Care in Diabetes—2025. Retinopathy, Neuropathy and Foot Care.
- American Academy of Ophthalmology. Diabetic Retinopathy Preferred Practice Pattern®.
- International Council of Ophthalmology. ICO Guidelines for Diabetic Eye Care.
- National Institute for Health and Care Excellence. Diabetic Retinopathy: Management and Screening.
- International Diabetes Federation. IDF Diabetes Atlas and Clinical Recommendations.
