Diabetes and the Eyes: How Diabetes Can Affect Your Vision

Author: Dr Val Phua
Estimated reading time: 24 minutes

Diabetes can affect almost every part of the eye.

Some effects are temporary, such as blurred vision when blood glucose changes rapidly.

Others may cause permanent visual loss, including:

• Diabetic retinopathy
• Diabetic macular oedema
• Vitreous haemorrhage
• Tractional retinal detachment
• Neovascular glaucoma
• Retinal ischaemia

Diabetes also increases the likelihood of developing:

• Cataract
• Glaucoma
• Dry-eye and ocular-surface problems
• Corneal-healing difficulties
• Certain eye infections
• Changes in spectacle prescription

The most important diabetic eye condition is diabetic retinopathy.

Diabetic retinopathy develops when prolonged metabolic and vascular stress damages the small blood vessels supplying the retina.

In its early stages, the person may have:

• Clear vision
• No pain
• No redness
• No warning symptoms

This is why retinal screening is essential even when the eyes feel completely normal.

Singapore’s public eye-care guidance recommends that people with diabetes undergo retinal screening at least once a year. Diabetic retinal photography is available at polyclinics and participating primary-care facilities through the Singapore Integrated Diabetic Retinopathy Programme.

Diabetic retinopathy is not inevitable.

The risk and rate of progression can be reduced through:

• Good long-term glucose control
• Appropriate blood-pressure control
• Management of cholesterol and kidney disease
• Smoking cessation
• Regular retinal screening
• Timely eye treatment

In the landmark Diabetes Control and Complications Trial, intensive glucose management reduced the development of retinopathy by 76% in people with type 1 diabetes who had no retinopathy at the beginning of the trial. It reduced further progression by 54% among those who already had early disease.

However, good glucose control does not replace eye examinations.

A person may develop retinopathy despite:

• Feeling well
• Having no visual symptoms
• Taking diabetes medication
• Having had a normal eye examination several years earlier

The central message is:

Diabetes can damage vision silently. Regular retinal screening detects disease before vision is affected, while good systemic control and timely treatment can prevent or substantially reduce many cases of severe visual loss.

The Quick Answer

How Does Diabetes Affect the Eyes?

Diabetes may affect vision through several mechanisms:

• Rapid blood-glucose changes may temporarily change focus.
• Retinal capillaries may leak blood or fluid.
• Retinal vessels may become blocked.
• The macula may become swollen.
• Abnormal new blood vessels may develop.
• Scar tissue may pull the retina away from the eye wall.
• The natural lens may become cloudy earlier.
• Abnormal blood vessels may block the eye’s drainage angle and raise eye pressure.
• Corneal healing and ocular-surface health may be impaired.

What Is Diabetic Retinopathy?

Diabetic retinopathy is damage to the retinal circulation caused by diabetes.

It may begin with tiny vascular abnormalities such as:

• Microaneurysms
• Small retinal haemorrhages
• Localised leakage

It can progress to:

• Widespread capillary closure
• Macular oedema
• Retinal ischaemia
• Abnormal new blood vessels
• Vitreous haemorrhage
• Tractional retinal detachment

Can Diabetic Retinopathy Cause Blindness?

Yes.

Diabetic retinopathy can cause severe and permanent visual loss when:

• The macula becomes chronically swollen or ischaemic.
• Abnormal vessels bleed into the vitreous.
• Scar tissue detaches the retina.
• Neovascular glaucoma develops.
• Treatment is started after irreversible retinal damage has occurred.

However, early disease can often be detected before symptoms appear, and timely treatment greatly reduces the risk of severe visual loss.

Does Everyone with Diabetes Develop Retinopathy?

No.

Risk increases with:

• Longer duration of diabetes
• Higher HbA1c
• High blood pressure
• Kidney disease
• Pregnancy
• Existing retinopathy
• Poor follow-up

Singapore population research has found that diabetes duration, HbA1c, blood-glucose level and systolic blood pressure are important risk factors for diabetic retinopathy across the country’s major ethnic groups.

How Often Should Someone with Diabetes Have an Eye Check?

In Singapore, annual diabetic retinal screening is generally recommended for people with diabetes. Retinal photography is subsidised at polyclinics and participating GP clinics and is included within chronic-disease care pathways.

International 2026 guidance recommends:

• Type 1 diabetes: an initial comprehensive retinal examination within five years after diabetes begins
• Type 2 diabetes: an examination at the time of diagnosis
• Existing retinopathy: examination at least annually and more frequently when progressing or sight-threatening
• No retinopathy with consistently good control: selected patients may be considered for one- to two-year intervals under an individualised programme

For practical Singapore care, patients should follow the interval stated in their retinal-photography or ophthalmology report rather than postponing screening themselves.

Can Diabetes Cause Blurred Vision Without Retinopathy?

Yes.

Rapid changes in blood glucose can temporarily alter the refractive properties of the natural lens.

Blur may occur:

• When glucose is very high
• During the first weeks after diabetes treatment begins
• When glucose falls rapidly from a previously high level
• When readings fluctuate substantially

Prospective studies have documented temporary refractive shifts during intensive glucose correction, sometimes lasting several weeks before stabilising.

A new pair of glasses should not always be prescribed immediately while glucose is changing rapidly.

Can Diabetic Eye Disease Be Reversed?

Some changes can improve.

For example:

• Macular oedema may improve with injections.
• Retinal haemorrhages may clear.
• Abnormal new vessels may regress after treatment.
• Vitreous blood may gradually absorb.
• A tractional detachment may be repaired surgically.

However, lost retinal or optic-nerve tissue may not regenerate.

Permanent visual loss may remain after:

• Macular ischaemia
• Longstanding macular oedema
• Retinal infarction
• Macular scarring
• Advanced tractional detachment
• Neovascular glaucoma
• Optic-nerve damage

What Is Diabetes?

Diabetes mellitus is a group of conditions in which blood glucose remains abnormally elevated because of problems involving:

• Insulin production
• Insulin action
• Both

The main forms include:

• Type 1 diabetes
• Type 2 diabetes
• Gestational diabetes
• Diabetes caused by medication, pancreatic disease or other medical conditions

Type 1 Diabetes

In type 1 diabetes, the immune system destroys the pancreatic cells that produce insulin.

Insulin treatment is required.

Retinopathy is uncommon immediately at diagnosis but becomes more likely as the duration of diabetes increases.

Type 2 Diabetes

Type 2 diabetes involves insulin resistance and progressive impairment of insulin production.

It may remain undiagnosed for years.

Retinopathy may therefore already be present when type 2 diabetes is first discovered.

This is why the initial retinal examination should occur at diagnosis rather than several years later.

Gestational Diabetes

Gestational diabetes develops during pregnancy in a person who was not previously known to have diabetes.

Gestational diabetes alone does not carry the same established retinopathy-progression risk as pre-existing type 1 or type 2 diabetes.

However, the mother still requires:

• Obstetric monitoring
• Glucose management
• Post-pregnancy diabetes follow-up

Women with pre-existing diabetes require specific retinal assessment during pregnancy.

Why High Blood Glucose Damages the Retina

The Retina Has a Fine Capillary Network

The retina is neural tissue that converts light into electrical signals.

It depends on a continuous supply of:

• Oxygen
• Glucose
• Nutrients
• Healthy blood flow

Its circulation contains extremely small blood vessels that are vulnerable to long-term metabolic injury.

Damage to the Blood-Vessel Lining

Persistent hyperglycaemia affects:

• Endothelial cells lining the vessels
• Pericytes supporting capillary walls
• Basement membranes
• Normal vascular regulation
• Inflammatory pathways

The capillary walls may become:

• Weak
• Leaky
• Abnormally thickened
• Poorly perfused

Breakdown of the Blood-Retinal Barrier

Healthy retinal vessels tightly regulate what passes from the blood into retinal tissue.

Diabetes can damage this barrier.

Fluid, blood proteins and lipids may then leak into the retina.

When leakage affects the macula, diabetic macular oedema may develop.

Capillary Closure

Some damaged capillaries become blocked.

The affected retina receives insufficient oxygen.

This is called retinal ischaemia.

Ischaemic retina releases signalling molecules including vascular endothelial growth factor, or VEGF.

Abnormal New Blood Vessels

High VEGF levels may stimulate fragile new blood vessels to grow on:

• The optic disc
• The retinal surface
• The iris
• The drainage angle of the eye

These vessels do not restore normal retinal circulation.

They are fragile and may:

• Bleed
• Form scar tissue
• Pull on the retina
• Block aqueous drainage
• Cause neovascular glaucoma

Stages of Diabetic Retinopathy

Diabetic retinopathy is broadly divided into:

• Non-proliferative diabetic retinopathy
• Proliferative diabetic retinopathy

Diabetic macular oedema can occur at any stage.

Non-Proliferative Diabetic Retinopathy

Non-proliferative diabetic retinopathy, or NPDR, means that retinal vascular damage is present but abnormal new vessels have not developed.

Mild NPDR

The earliest visible finding is commonly one or more microaneurysms.

Vision is usually normal.

Moderate NPDR

Additional changes may include:

• Retinal haemorrhages
• Hard exudates
• Cotton-wool spots
• Venous abnormalities
• Intraretinal microvascular abnormalities
• Greater capillary leakage or closure

Severe NPDR

Severe NPDR indicates substantial retinal ischaemia and a high risk of progression to proliferative disease.

Findings may include:

• Numerous haemorrhages
• Marked venous beading
• Prominent intraretinal microvascular abnormalities
• Widespread capillary non-perfusion

The person may still have good central vision when the macula is unaffected.

Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy, or PDR, develops when ischaemia causes abnormal retinal new vessels.

These may grow:

• On the optic disc
• Elsewhere on the retina
• Along the back surface of the vitreous

PDR is sight-threatening even when the patient can still read the eye chart well.

Why the New Vessels Are Dangerous

The new vessels are:

• Fragile
• Poorly supported
• Prone to bleeding
• Associated with fibrous tissue

Possible complications include:

• Vitreous haemorrhage
• Preretinal haemorrhage
• Fibrovascular scarring
• Tractional retinal detachment
• Combined tractional and rhegmatogenous detachment

Diabetic Macular Oedema

What Is the Macula?

The macula is the central portion of the retina responsible for:

• Reading
• Facial recognition
• Fine detail
• Colour discrimination
• Driving vision

At the centre of the macula is the fovea, which provides the sharpest vision.

What Is Diabetic Macular Oedema?

Diabetic macular oedema, or DME, occurs when damaged retinal vessels leak fluid into the macula.

The retina becomes thickened and its normal structure is disturbed.

Centre-Involving DME

Centre-involving DME affects the foveal centre.

It is more likely to reduce:

• Reading vision
• Distance clarity
• Contrast
• Fine visual detail

Non-Centre-Involving DME

Fluid or retinal thickening may lie away from the foveal centre.

Vision may remain normal.

The condition may be:

• Observed
• Treated with laser in selected cases
• Managed according to its location and progression

Symptoms of DME

Possible symptoms include:

• Central blur
• Distorted lines
• Difficulty reading
• Washed-out colours
• Reduced contrast
• Unequal vision between the eyes
• Difficulty recognising faces

DME may also be present without noticeable symptoms, particularly when one eye compensates for the other.

Does the Amount of Retinopathy Predict the Amount of Macular Oedema?

Not perfectly.

A patient with relatively mild visible retinopathy may develop centre-involving DME.

Another patient may have extensive peripheral retinopathy without central swelling.

This is one reason OCT is often required in addition to retinal photography.

Symptoms of Diabetic Retinopathy

Early Disease

Early diabetic retinopathy usually causes no symptoms.

Normal vision does not prove that the retina is normal.

Later Symptoms

Symptoms may include:

• Blurred vision
• Distortion
• Floaters
• Cobwebs
• Dark patches
• Reduced contrast
• Difficulty seeing at night
• Washed-out colours
• Sudden severe loss of vision
• A curtain or shadow

Singapore public eye-care guidance emphasises that symptoms commonly appear only once disease is moderate or advanced.

Sudden Floaters

A sudden shower of black spots or cobwebs may indicate:

• Vitreous haemorrhage
• Posterior vitreous detachment
• Retinal tear
• Retinal detachment

A diabetic patient should not assume that sudden floaters are harmless.

Sudden Cloudy Vision

Blood entering the vitreous may produce:

• Red or black spots
• Hazy vision
• A smoky appearance
• Severe visual reduction

The bleeding may be caused by proliferative retinopathy.

A Curtain or Shadow

A curtain, shadow or missing field may indicate retinal detachment.

A tractional detachment can progress gradually, but sudden visual loss may occur when:

• The macula detaches
• A retinal tear develops
• Vitreous haemorrhage occurs

Risk Factors for Diabetic Retinopathy

Duration of Diabetes

The longer a person has diabetes, the greater the cumulative retinal exposure.

Duration is one of the strongest risk factors.

Glucose Control

Higher HbA1c is associated with:

• Greater retinopathy risk
• Faster progression
• Greater likelihood of sight-threatening disease

Singapore population data found that every percentage-point increase in HbA1c was associated with increased diabetic-retinopathy risk.

Blood Pressure

High blood pressure adds stress to already damaged retinal vessels.

Blood-pressure treatment has a modest overall benefit in preventing diabetic retinopathy, particularly among people with type 2 diabetes and hypertension.

The UK Prospective Diabetes Study found that tighter blood-pressure control reduced:

• Retinopathy progression
• Retinal laser treatment
• Loss of visual acuity

among participants with type 2 diabetes and hypertension.

Kidney Disease

Diabetic kidney disease and retinopathy often coexist because both involve small-vessel injury.

Albumin in the urine or reduced kidney function may indicate greater microvascular risk.

Cholesterol and Lipids

Abnormal blood lipids may contribute to:

• Hard exudates
• Macular leakage
• General cardiovascular risk

Fenofibrate has reduced diabetic-retinopathy progression in selected clinical trials, including the LENS trial, but it is a systemic medication with specific indications and is not an eye supplement. It should be considered by the patient’s medical team rather than started solely from internet advice.

Pregnancy

Pregnancy can accelerate retinopathy in women with pre-existing diabetes.

Risk is greater with:

• Existing retinopathy
• Longer diabetes duration
• Poor pre-pregnancy control
• Rapid glucose improvement
• High blood pressure
• Kidney disease

Meta-analyses confirm that diabetic retinopathy can develop or progress during pregnancies complicated by pre-existing type 1 or type 2 diabetes.

Smoking

Smoking worsens overall vascular and cardiovascular health.

Its specific association with diabetic retinopathy varies between study populations, but smoking cessation remains essential for reducing:

• Heart disease
• Stroke
• Kidney disease
• Cataract
• Macular degeneration
• General diabetes complications

Anaemia and Sleep Apnoea

Anaemia may reduce oxygen delivery to already ischaemic retinal tissue.

Obstructive sleep apnoea may worsen:

• Blood-pressure control
• Oxygen fluctuations
• Metabolic health

These conditions should be treated when present.

Puberty

Retinopathy is uncommon before puberty in children with short-duration diabetes.

Risk increases with:

• Pubertal hormonal changes
• Longer diabetes duration
• Poorer glucose control

Children and teenagers require screening according to paediatric diabetes guidance.

Temporary Blurred Vision from Glucose Changes

Why Does the Prescription Change?

The natural lens is exposed to glucose within the aqueous fluid.

Substantial changes in glucose can alter:

• Lens hydration
• Lens refractive index
• Focusing properties

The result may be a temporary shift towards:

• More short-sightedness
• More long-sightedness

The direction is not always predictable.

Blur After Starting Diabetes Treatment

A patient newly diagnosed with very high glucose may notice that vision becomes more blurred after treatment begins.

This does not necessarily mean that the medication damaged the eyes.

Rapid glucose correction may temporarily change the lens’s refractive state. Studies have documented transient hyperopic shifts during intensive treatment, with changes related to the previous glucose level and the speed of glucose reduction.

Should New Glasses Be Made Immediately?

When glucose is changing substantially, it may be sensible to delay a final prescription until:

• Glucose has stabilised
• Vision is no longer fluctuating
• The retina has been assessed
• Other causes of blur have been excluded

Temporary glasses may occasionally be required for work or safety.

Blur Should Not Automatically Be Blamed on Glucose

A person with diabetes may also develop:

• Cataract
• DME
• Retinal detachment
• Retinal vascular occlusion
• Glaucoma
• Corneal disease

Persistent or one-sided blur requires an eye examination.

Diabetic Retinal Screening in Singapore

Why Screening Is Necessary

Diabetic retinopathy may be advanced before vision deteriorates.

Screening aims to detect:

• Retinopathy
• Referable maculopathy
• Sight-threatening disease
• Other retinal abnormalities

before irreversible visual loss occurs.

Diabetic Retinal Photography

Retinal photographs are taken through the pupil.

Depending on the system:

• The pupils may or may not require dilation.
• One or more photographs are taken of each eye.
• Images are assessed by trained graders or supported by validated technology.
• A report is sent to the referring clinic.
• Abnormal or ungradable images result in referral.

Singapore’s integrated screening programme transmits retinal photographs from primary-care sites to centralised reading services for assessment.

Where Is Screening Available?

Subsidised diabetic retinal photography is available through:

• Polyclinics
• Participating GP clinics
• Primary Care Networks
• Selected family-medicine and community facilities

It is included within the Healthier SG chronic-disease care framework.

Is Retinal Photography the Same as a Full Eye Examination?

No.

Retinal photography is an effective screening method, but it may not fully assess:

• Cataract
• Corneal disease
• Eye pressure
• Peripheral retinal tears
• Visual fields
• Eye alignment
• Refractive error
• Symptoms not explained by the photograph

An ophthalmic examination is needed when:

• Photographs are abnormal
• Images cannot be graded
• Vision has changed
• Eye pain or redness is present
• Another eye disease is suspected

What If the Photograph Is Ungradable?

Images may be ungradable because of:

• Cataract
• Small pupils
• Corneal opacity
• Poor fixation
• Previous surgery
• Vitreous haemorrhage
• Technical limitations

An ungradable result is not the same as a normal result.

The patient should attend the recommended eye referral.

Screening Schedule

A practical approach is:

Type 1 Diabetes

• Initial retinal examination within approximately five years after onset
• Earlier when clinically indicated
• Regular subsequent screening

Type 2 Diabetes

• Retinal examination or photography at diagnosis
• Regular screening thereafter

Existing Retinopathy

• At least annual review
• More frequent review according to severity

Pregnancy with Pre-Existing Diabetes

• Ideally before conception
• Early in the first trimester
• Further reviews according to retinal findings

Singapore’s previous national clinical guidance recommends examination before conception and during the first trimester for women with known diabetes.

What Tests Are Used to Diagnose Diabetic Eye Disease?

Visual Acuity

Each eye is tested separately.

This identifies:

• Central visual loss
• Differences between the eyes
• Response to treatment

Good acuity does not exclude peripheral proliferative retinopathy.

Refraction

Refraction checks whether blur is caused by:

• Myopia
• Hyperopia
• Astigmatism
• Presbyopia
• Temporary glucose-related change

Slit-Lamp Examination

The front of the eye is checked for:

• Cataract
• Corneal disease
• Dry eye
• Iris new vessels
• Inflammation

Eye-Pressure Measurement

Pressure is measured to assess for:

• Glaucoma
• Neovascular glaucoma
• Steroid-related pressure elevation

Dilated Retinal Examination

Dilation allows assessment of:

• Microaneurysms
• Haemorrhages
• Exudates
• New vessels
• Vitreous haemorrhage
• Traction
• Retinal detachment
• Macular changes

Fundus Photography

Photography records:

• Distribution
• Severity
• Progression
• Treatment response

Ultra-widefield photography may show more peripheral retina but does not replace every aspect of examination.

Optical Coherence Tomography

OCT provides cross-sectional images of the macula.

It can identify:

• Intraretinal fluid
• Subretinal fluid
• Retinal thickening
• Vitreomacular traction
• Epiretinal membrane
• Macular atrophy
• Treatment response

OCT is central to the diagnosis and monitoring of DME.

OCT Angiography

OCT angiography maps retinal and choroidal blood flow without dye injection.

It may demonstrate:

• Capillary non-perfusion
• Enlargement of the foveal avascular zone
• Abnormal vascular networks

It does not show leakage in the same way as fluorescein angiography.

Fluorescein Angiography

A fluorescent dye is injected into a vein and retinal photographs are taken.

It may identify:

• Leakage
• Ischaemia
• New vessels
• Areas suitable for laser
• Causes of unexplained visual loss

Ultrasound

B-scan ultrasonography may be needed when the retina cannot be seen because of:

• Dense vitreous haemorrhage
• Cataract
• Other media opacity

It can help identify:

• Retinal detachment
• Traction
• Vitreous membranes
• Other internal abnormalities

Treating Diabetic Retinopathy

Treatment depends on:

• Retinopathy stage
• Macular involvement
• Visual acuity
• Retinal ischaemia
• Follow-up reliability
• Pregnancy
• Other eye disease
• Systemic health

Systemic Risk-Factor Control

Every stage requires attention to:

• Glucose
• Blood pressure
• Cholesterol
• Kidney function
• Smoking
• Medication adherence

Systemic control supports both eyes and reduces other diabetes complications.

It does not replace direct eye treatment when sight-threatening disease is already present.

Anti-VEGF Injections

Anti-VEGF medicines reduce signalling that causes:

• Vascular leakage
• Macular swelling
• Abnormal new-vessel growth

They are injected into the vitreous cavity under sterile conditions.

Current standards recommend anti-VEGF treatment as first-line therapy for most eyes with centre-involving DME that reduces visual acuity.

Available agents may include:

• Aflibercept
• Bevacizumab
• Ranibizumab
• Faricimab
• Other approved or locally used medicines

Selection depends on:

• Baseline vision
• OCT findings
• Previous response
• Treatment interval
• Cost
• Availability
• Medical considerations

How Many Injections Are Needed?

There is no universal fixed number.

Treatment commonly begins with:

• Frequent loading injections
• Close OCT monitoring
• Extension or reduction of intervals according to response

Some patients require:

• A limited course
• Long-term intermittent treatment
• Ongoing treatment for several years

Stopping follow-up because vision has improved may allow swelling to recur.

Comparing Anti-VEGF Medicines

A major comparative trial found that aflibercept, bevacizumab and ranibizumab all improved vision in DME.

When initial visual loss was mild, average differences were small.

When initial vision was worse, aflibercept produced greater average early improvement than bevacizumab.

Individual treatment decisions may differ from trial averages.

DME with Good Vision

When OCT shows centre-involving DME but visual acuity remains good, immediate injections are not always necessary.

Protocol V found that careful observation with treatment only if vision worsened produced similar average two-year visual outcomes to immediate aflibercept or laser in appropriately monitored eyes.

This approach requires reliable follow-up.

Observation does not mean ignoring the condition.

Panretinal Photocoagulation

Panretinal photocoagulation, or PRP, applies laser burns to the peripheral retina.

The treatment reduces the drive for abnormal new-vessel growth.

It is used mainly for:

• High-risk proliferative diabetic retinopathy
• Selected severe NPDR
• Iris or angle new vessels
• Situations where follow-up reliability is a concern

PRP has greatly reduced severe visual loss from proliferative retinopathy.

Does PRP Improve Vision?

Its main purpose is to preserve vision by reducing the risk of:

• Vitreous haemorrhage
• Tractional detachment
• Neovascular glaucoma

It does not usually restore vision already lost from macular ischaemia.

Possible Effects of PRP

Possible effects include:

• Reduced peripheral field
• Reduced night vision
• Temporary blur
• Macular swelling
• Difficulty adapting between light and dark
• Rare inflammation or bleeding

The benefit generally outweighs these risks when high-risk proliferative disease is present.

Anti-VEGF Versus PRP for Proliferative Disease

Anti-VEGF injections may also cause new vessels to regress and can be an alternative to PRP for selected patients.

Advantages may include:

• Less peripheral-field loss
• Less DME
• Lower vitrectomy rates in some trials

Limitations include:

• More frequent appointments
• Continued injections
• Risk of rapid recurrence if treatment is interrupted

Current standards consider anti-VEGF a reasonable alternative to PRP for selected proliferative diabetic retinopathy.

Macular Laser

Focal or grid laser may still be used for:

• Non-centre-involving DME
• Persistent leakage
• Selected eyes not suitable for injections
• Treatment combined with other therapies

Anti-VEGF treatment has replaced laser as first-line therapy for most vision-impairing centre-involving DME.

Steroid Treatment

Intravitreal steroids may reduce inflammation and vascular leakage.

Options include:

• Steroid injections
• Sustained-release implants

They may be considered when:

• DME persists despite anti-VEGF
• Anti-VEGF is unsuitable
• The patient has undergone cataract surgery
• Treatment burden requires another approach

Possible complications include:

• Cataract
• Raised eye pressure
• Glaucoma
• Infection
• Inflammation

Vitrectomy

Vitrectomy removes the vitreous gel and allows the surgeon to treat:

• Non-clearing vitreous haemorrhage
• Tractional retinal detachment
• Combined retinal detachment
• Dense fibrovascular membranes
• Selected tractional DME
• Severe proliferative complications

A recent review confirms that vitreous haemorrhage and tractional retinal detachment remain major indications for diabetic vitrectomy.

Can Surgery Restore Normal Vision?

The result depends on:

• Macular attachment
• Retinal ischaemia
• Duration of detachment
• Optic-nerve health
• Pre-existing DME
• Surgical complexity

Surgery may:

• Clear blood
• Reattach the retina
• Prevent further deterioration
• Improve useful vision

It cannot always restore normal central detail.

Diabetes and Cataract

Why Does Diabetes Increase Cataract Risk?

High glucose and long-term metabolic stress affect the natural lens.

Diabetes is associated with:

• Earlier cataract development
• Faster progression
• More rapid prescription change
• Greater likelihood of cataract surgery

Important diabetes-related risk factors include:

• Higher HbA1c
• Longer diabetes duration
• Existing diabetic retinopathy

Symptoms of Cataract

Possible symptoms include:

• Gradual blur
• Glare
• Halos
• Faded colours
• Difficulty driving at night
• Frequent spectacle changes
• Double or multiple images in one eye

Can Better Glucose Control Clear a Cataract?

No.

Temporary refractive blur may improve when glucose stabilises.

An established cataract is a structural opacity and does not dissolve when glucose improves.

Cataract Surgery in People with Diabetes

Many patients with diabetes achieve excellent cataract-surgery results.

Preoperative assessment should consider:

• Retinopathy severity
• DME
• Macular ischaemia
• Kidney disease
• Glucose control
• Previous retinal treatment
• Lens choice
• Risk of postoperative macular swelling

The retina should be examined before surgery whenever possible.

Should Retinopathy Be Treated Before Cataract Surgery?

Treatment may be required first when there is:

• Active proliferative retinopathy
• Significant DME
• Iris new vessels
• A high risk of retinal complications

The sequence should be individualised.

Dense cataract may sometimes need removal before the retina can be fully assessed or treated.

Diabetes and Glaucoma

Open-Angle Glaucoma

Meta-analyses suggest that diabetes is associated with a modestly increased risk of open-angle glaucoma.

The exact relationship may involve:

• Vascular factors
• Metabolic stress
• Age
• Eye pressure
• Shared risk factors

Patients still require standard glaucoma assessment rather than assuming that diabetes alone proves the diagnosis.

Neovascular Glaucoma

Neovascular glaucoma is a severe complication of retinal ischaemia.

Abnormal blood vessels grow over the:

• Iris
• Drainage angle

Scar tissue then closes the angle and prevents fluid from leaving the eye.

This may cause:

• Very high eye pressure
• Severe pain
• Redness
• Corneal clouding
• Headache
• Nausea
• Rapid visual loss

Treatment may require:

• Anti-VEGF injection
• Panretinal laser
• Eye-pressure medication
• Glaucoma surgery
• Retinal treatment

Neovascular glaucoma is an eye emergency.

Diabetes and the Ocular Surface

Diabetes may affect:

• Corneal nerves
• Corneal sensitivity
• Epithelial healing
• Tear-film stability
• Eyelid and meibomian-gland function

Possible symptoms include:

• Dryness
• Burning
• Fluctuating vision
• Grittiness
• Contact-lens intolerance

Reduced corneal sensation can sometimes make a significant epithelial injury feel less painful than expected.

Contact Lenses

People with well-controlled diabetes may wear contact lenses when:

• Corneal health is good
• Hygiene is reliable
• Sensation is adequate
• Follow-up is maintained

Lens wear should stop immediately for:

• Pain
• Redness
• Light sensitivity
• Discharge
• Reduced vision

Diabetes and Eye Infections

Diabetes, particularly when poorly controlled, may impair:

• Immune response
• Wound healing
• Epithelial repair

The person should seek prompt care for:

• Corneal ulcer
• Eyelid infection
• Postoperative infection
• Severe conjunctival inflammation

Pregnancy and Diabetic Retinopathy

Pre-Pregnancy Assessment

Women with type 1 or type 2 diabetes who plan pregnancy should ideally have a retinal examination before conception.

This allows:

• Retinopathy staging
• Treatment before pregnancy
• Baseline documentation
• Planning of follow-up

During Pregnancy

A retinal examination should occur early in the first trimester.

Further review depends on:

• Baseline retinopathy
• Glucose control
• Blood pressure
• Kidney disease
• Rate of progression

Pregnancy-associated progression may continue for a period after delivery, so postpartum review may be required.

Gestational Diabetes

Gestational diabetes without pre-existing diabetes does not usually require the same retinopathy-surveillance schedule.

However, women with gestational diabetes remain at increased future risk of type 2 diabetes and should complete the recommended metabolic follow-up.

Rapid Glucose Improvement and Early Worsening

Long-term glucose control protects the retina.

However, rapid improvement from longstanding severe hyperglycaemia can occasionally cause temporary early worsening of existing retinopathy.

Risk is greater when there is:

• High starting HbA1c
• Advanced retinopathy
• A large rapid HbA1c reduction
• Pregnancy
• Longstanding diabetes

This does not mean that glucose should remain uncontrolled.

It means that patients with established retinopathy may require closer retinal monitoring while glucose is improved safely.

Diabetes Medicines and the Eyes

Diabetes medication should not be stopped because of an internet report about an eye complication.

The benefits of improving:

• Glucose
• Weight
• Cardiovascular risk
• Kidney health

may be substantial.

When treatment is expected to lower HbA1c rapidly, a patient with known moderate or severe diabetic retinopathy should discuss:

• Current retinal status
• Screening interval
• New visual symptoms
• Need for closer review

with the diabetes and eye-care teams.

Preventing Diabetic Visual Loss

Know Your HbA1c

HbA1c reflects average glucose exposure over approximately two to three months.

For many adults, a target around 7% is commonly used, but the target should be individualised according to:

• Age
• Hypoglycaemia risk
• Pregnancy
• Kidney disease
• Cardiovascular disease
• Duration of diabetes
• Other medical conditions

Singapore eye-care guidance notes that HbA1c below 7% is an appropriate goal for many patients, while emphasising that individual medical advice is required.

Control Blood Pressure

Blood pressure is a major modifiable risk factor.

Take prescribed medication consistently and monitor at home when advised.

Manage Cholesterol

Management may include:

• Dietary changes
• Statins
• Other lipid-lowering treatment
• Fenofibrate in selected patients

The decision should consider overall cardiovascular and kidney health.

Stop Smoking

Smoking worsens:

• Vascular injury
• Cardiovascular risk
• Kidney risk
• Cataract
• Macular degeneration

Exercise Regularly

Exercise can support:

• Glucose control
• Blood pressure
• Weight management
• Cardiovascular health
• Insulin sensitivity

Patients with advanced proliferative retinopathy may need advice before:

• Heavy weightlifting
• High-impact activity
• Activities involving straining or inversion

because of the risk of bleeding or traction.

Attend Screening Even When Vision Is Good

Do not wait for:

• Blur
• Floaters
• Distortion
• Pain

The best opportunity to prevent blindness is often before symptoms begin.

Do Not Miss Retinal Treatment

Anti-VEGF and laser treatment may lose effectiveness when follow-up is repeatedly interrupted.

Missed appointments can allow:

• DME to recur
• New vessels to regrow
• Bleeding
• Traction
• Neovascular glaucoma

Common Myths

“My Vision Is Clear, So My Retina Must Be Normal”

False.

Early and even advanced peripheral retinopathy may be asymptomatic.

“Diabetic Retinopathy Only Happens in Type 1 Diabetes”

False.

It affects both type 1 and type 2 diabetes.

“I Have Only Mild Diabetes, So I Do Not Need Eye Screening”

False.

Retinal risk depends on more than whether medication is described as mild or strong.

“Taking Diabetes Medication Means Retinopathy Cannot Develop”

False.

Medication reduces risk when it achieves good long-term control, but screening remains necessary.

“Diabetic Retinopathy Always Causes Pain”

False.

Most retinal disease is painless.

“Blurred Vision Means I Need Stronger Glasses”

Not always.

Blur may result from:

• Glucose fluctuation
• Cataract
• DME
• Vitreous haemorrhage
• Retinal detachment

“Retinal Photography Checks Every Eye Disease”

False.

It is primarily a retinal screening test.

“One Normal Photograph Protects Me for Life”

False.

Retinopathy can develop later.

“A Normal HbA1c Means Eye Screening Is Unnecessary”

False.

Duration, past glucose exposure, blood pressure and other factors also matter.

“Once Retinopathy Starts, Blindness Is Inevitable”

False.

Many patients retain useful vision with monitoring and treatment.

“Eye Injections Cure Diabetes”

False.

They treat retinal leakage or abnormal vessels.

“One Injection Is Usually Enough”

Not necessarily.

DME often requires repeated treatment.

“Laser Makes the Retina Normal Again”

False.

Laser reduces future risk but does not restore dead retinal tissue.

“Laser Always Causes Blindness”

False.

PRP is used to prevent severe visual loss from proliferative disease.

“Blood in the Eye Will Always Clear Without Treatment”

False.

The cause must be treated, and some haemorrhages require surgery.

“A Cataract Is Diabetic Retinopathy”

False.

A cataract affects the natural lens.

Retinopathy affects the retina.

“Better Glucose Control Can Dissolve a Cataract”

False.

“Pregnancy-Related Retinopathy Always Settles After Delivery”

False.

Progression may continue and treatment may still be required.

“Rapid Glucose Control Should Be Avoided Because It Worsens Retinopathy”

False.

Long-term control is beneficial.

Patients at higher risk require coordinated and appropriately monitored improvement rather than ongoing hyperglycaemia.

“Eye Vitamins Prevent Diabetic Retinopathy”

Unproven.

No vitamin replaces glucose, blood-pressure and retinal management.

“Carrots Reverse Diabetic Eye Disease”

False.

“Diabetic Retinopathy Is Caused by Eating Sugar on One Occasion”

False.

It reflects cumulative metabolic and vascular injury rather than one dessert.

Frequently Asked Questions

Can Prediabetes Affect the Eyes?

Prediabetes is associated with metabolic and vascular changes, but classic diabetic retinopathy is less common than in established diabetes.

A person with prediabetes should focus on preventing progression to diabetes and attend eye assessment when symptoms or other risk factors are present.

Can Diabetes Cause Sudden Blindness?

Yes.

Possible causes include:

• Vitreous haemorrhage
• Retinal detachment
• Retinal artery occlusion
• Neovascular glaucoma
• Severe retinal ischaemia

Sudden visual loss requires urgent assessment.

Can Diabetes Cause Floaters?

It may cause floaters when abnormal retinal vessels bleed.

A sudden increase in floaters is not normal.

Can Diabetes Cause Flashes?

Flashes may occur from:

• Vitreous traction
• Retinal tear
• Retinal detachment

They are not a typical early symptom of uncomplicated diabetic retinopathy.

Can Diabetes Cause Double Vision?

Yes, indirectly.

Diabetes may affect a nerve controlling the eye muscles, causing an acute cranial-nerve palsy.

New double vision still requires examination to exclude:

• Stroke
• Aneurysm
• Thyroid eye disease
• Myasthenia
• Other neurological conditions

Can Diabetes Affect Colour Vision?

Colour perception may be reduced by:

• DME
• Macular ischaemia
• Cataract
• Optic-nerve disease
• Advanced retinal damage

Can Diabetes Cause Night-Vision Problems?

Possible causes include:

• Cataract
• Reduced contrast sensitivity
• Extensive PRP
• Retinal ischaemia
• Other retinal disease

Can Diabetic Retinopathy Improve on Its Own?

Mild lesions may fluctuate, but patients should not depend on spontaneous improvement.

Systemic control and follow-up determine whether observation is safe.

How Quickly Can Retinopathy Progress?

Progression may occur over years or, in high-risk situations, much faster.

Faster progression may occur with:

• Severe NPDR
• Pregnancy
• Poor glucose control
• High blood pressure
• Kidney disease
• Rapid metabolic change
• Missed follow-up

Can One Eye Be Worse?

Yes.

Diabetic retinopathy is usually bilateral but may be asymmetrical.

Marked asymmetry may prompt evaluation for:

• Carotid disease
• Retinal vein occlusion
• Previous retinal treatment
• Other local eye disease

Can Retinal Bleeding Be Seen from Outside?

Usually not.

The white of the eye may appear normal despite extensive internal retinal bleeding.

Do I Need Dilation Every Year?

Retinal photography may be performed without dilation in some programmes.

Dilation is required when:

• Images are inadequate
• Retinopathy is present
• Symptoms develop
• A full examination is needed

Can I Drive After Retinal Photography?

Usually yes when the pupils are not dilated.

When dilating drops are used, glare and blur may temporarily affect driving.

Arrange alternative transport when advised.

Can I Exercise with Diabetic Retinopathy?

Most exercise is beneficial.

Patients with active proliferative retinopathy, recent vitreous haemorrhage or traction may need to avoid strenuous activity until reviewed.

Can I Have Cataract Surgery with Retinopathy?

Yes.

The retina should be assessed and treated where necessary.

Visual expectations depend on macular and optic-nerve health.

Can I Have LASIK or SMILE if I Have Diabetes?

Diabetes is not always an absolute contraindication.

Suitability depends on:

• Glucose stability
• Retinopathy
• Corneal health
• Wound healing
• Prescription stability
• General health

Does Insulin Cause Retinopathy?

No.

Insulin treats diabetes.

Early worsening may occasionally occur when severe longstanding hyperglycaemia improves rapidly, but the long-term retinal benefit of good glucose control is well established.

Does Anti-VEGF Affect Blood Sugar?

Anti-VEGF eye injections do not generally alter blood glucose meaningfully.

The ophthalmologist should still know about:

• Recent stroke
• Recent heart attack
• Pregnancy
• Other medical conditions

How Often Will I Need Anti-VEGF?

The interval is based on:

• OCT
• Vision
• Previous response
• Recurrence
• Treatment protocol

Can DME Return?

Yes.

Recurrence may occur after months or years.

What Happens if I Miss an Injection?

The macula may swell again, and proliferative vessels may reactivate.

Contact the treating clinic to rearrange the appointment rather than waiting for the next routine date.

Can Diabetic Retinopathy Be Prevented Completely?

Not always.

Good systemic control and screening substantially reduce risk and severity but cannot guarantee prevention.

When to Seek Urgent Eye Care

Seek prompt or same-day assessment for:

• Sudden visual loss
• A sudden shower of floaters
• New cobwebs or a smoky haze
• Flashes of light
• A curtain or shadow
• New central distortion
• Sudden double vision
• A painful red eye
• Severe headache with visual change
• Sudden loss of colour or contrast
• Rapid worsening during pregnancy

These symptoms may indicate:

• Vitreous haemorrhage
• Retinal tear
• Retinal detachment
• Neovascular glaucoma
• Retinal vascular occlusion
• Cranial-nerve palsy
• Stroke
• Another eye emergency

A Diabetes and Eye-Health Checklist

Annual Care

• Have I attended diabetic retinal screening?
• Was the result normal, abnormal or ungradable?
• Do I know when the next test is due?
• Have I attended the referral if abnormalities were found?

Glucose Management

• Do I know my latest HbA1c?
• Is my glucose fluctuating substantially?
• Have I recently started intensive treatment?
• Has my vision changed during glucose correction?

Vascular Risk

• Is my blood pressure controlled?
• Is my cholesterol being treated?
• Has my kidney function been checked?
• Do I smoke?
• Do I have sleep-apnoea symptoms?

Eye Symptoms

• Is one eye blurrier?
• Are straight lines distorted?
• Have colours become duller?
• Are there new floaters?
• Is there a curtain or shadow?
• Is there eye pain or redness?

Before Pregnancy

• Have I had a retinal examination?
• Is existing retinopathy treated?
• Are glucose and blood pressure being managed safely?
• Is postpartum follow-up planned?

Questions to Ask the Eye Specialist

• Do I have diabetic retinopathy?
• What stage is it?
• Is the macula swollen?
• Is the macula ischaemic?
• Are abnormal new vessels present?
• Do I need injections, laser or surgery?
• How frequently should I be reviewed?
• Can I exercise normally?
• Is cataract contributing to my blur?
• What symptoms require urgent review?

The Bottom Line

Diabetes can affect vision through:

• Temporary refractive changes
• Diabetic retinopathy
• Diabetic macular oedema
• Vitreous haemorrhage
• Tractional retinal detachment
• Neovascular glaucoma
• Cataract
• Ocular-surface and corneal disease

Early diabetic retinopathy often causes no symptoms.

A person may have clear vision while retinal vessels are already:

• Leaking
• Closing
• Becoming ischaemic
• Developing abnormal new vessels

This is why regular retinal screening is essential.

In Singapore:

• Annual diabetic retinal screening is generally recommended.
• Retinal photography is available through polyclinics and participating primary-care clinics.
• Subsidies are available within chronic-disease and Healthier SG care pathways.

The most important modifiable factors are:

• Long-term glucose control
• Blood-pressure control
• Cholesterol and kidney management
• Smoking cessation
• Consistent medical care
• Timely retinal treatment

Intensive glucose management has produced large reductions in the development and progression of diabetic retinopathy in clinical trials.

When sight-threatening disease develops, treatment may include:

• Anti-VEGF injections
• Panretinal laser
• Macular laser
• Intravitreal steroids
• Vitrectomy

Anti-VEGF treatment is first-line therapy for most vision-impairing centre-involving diabetic macular oedema. PRP and anti-VEGF are both established approaches for selected proliferative retinopathy.

The most important message is:

Do not wait for blurred vision before checking the retina. Diabetic eye disease is most treatable before severe visual loss has occurred, and a normal-looking, comfortable eye may still contain significant retinopathy.

References

1. American Diabetes Association Professional Practice Committee. Retinopathy, neuropathy and foot care: Standards of Care in Diabetes—2026. Diabetes Care. 2026.
2. Ministry of Health Singapore. Clinical Practice Guidelines: Diabetes Mellitus—prevention and management of eye complications.
3. Ministry of Health Singapore. Details of eye screening and subsidies under Healthier SG.
4. HealthHub Singapore. Diabetic Retinal Photography.
5. SingHealth. Diabetic Retinopathy: causes, symptoms, screening and treatment.
6. Diabetes Control and Complications Trial Research Group. Effect of intensive treatment of diabetes on the development and progression of long-term complications. N Engl J Med. 1993. PMID: 8366922.
7. Wong TY, et al. Ethnic differences in prevalence and risk factors for diabetic retinopathy: Singapore Epidemiology of Eye Diseases Study. PMID: 29217148.
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10. UK Prospective Diabetes Study Group. Tight blood-pressure control and microvascular complications in type 2 diabetes. PMID: 9732337.
11. Matthews DR, et al. Tight blood-pressure control and progression of diabetic retinopathy. PMID: 15534123.
12. Cochrane Eyes and Vision Group. Blood-pressure control for diabetic retinopathy. PMID: 36975019.
13. American Diabetes Association. Treatment recommendations for diabetic macular oedema and proliferative diabetic retinopathy.
14. Wells JA, et al. Aflibercept, bevacizumab or ranibizumab for diabetic macular oedema. PMID: 25692915.
15. DRCR Retina Network. Initial observation for centre-involving diabetic macular oedema with good vision. PMID: 32077907.
16. Bain SC, et al. Early worsening of diabetic retinopathy following intensive glycaemic control. PMID: 30238577.
17. Association of pregnancy with diabetic-retinopathy progression: systematic review and meta-analysis. PMID: 36098625.
18. Global estimates of diabetic retinopathy in women with pre-existing diabetes during pregnancy. PMID: 35357410.
19. Effect of fenofibrate on progression of diabetic retinopathy: LENS trial. PMID: 38905569.
20. Vitrectomy for diabetic retinopathy: indications, outcomes and complications. PMID: 39803397.