DIABETIC RETINOPATHY

✓ Medically ReviewedDISEASEID: MDBT0265🚨 TRIAGE: URGENTICD-10: E14.3

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Definition

CLINICAL DEFINITION

Diabetic retinopathy is a chronic, progressive microvascular and neurodegenerative disease of the retina resulting from sustained hyperglycaemia in diabetes mellitus. It is classified into two principal stages: non-proliferative diabetic retinopathy (NPDR), characterised by microaneurysms, intraretinal haemorrhage, hard exudates, cotton-wool spots, venous beading, and intraretinal microvascular abnormalities in the absence of neovascularisation; and proliferative diabetic retinopathy (PDR), defined by the presence of neovascularisation of the optic disc, neovascularisation elsewhere, or vitreous haemorrhage. Diabetic macular oedema (DME) may complicate any stage and is a major mechanism of vision loss. Diagnosis is clinical, based on dilated fundus examination and retinal imaging.

IN PLAIN ENGLISH

Diabetic retinopathy is eye damage caused by long-term high blood sugar in diabetes. The small blood vessels in the light-sensitive lining at the back of the eye (the retina) become damaged, leak, or grow abnormally. It can lead to vision loss and blindness if not detected and treated early, which is why regular eye screening is important for everyone with diabetes.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Diabetic retinopathy is NOT defined solely by the presence of any retinal haemorrhage or exudate in a person with diabetes; other retinal vascular diseases, such as hypertensive retinopathy, retinal vein occlusion, ocular ischaemic syndrome, and radiation retinopathy, can produce overlapping findings and must be distinguished. Diabetic retinopathy is also NOT synonymous with diabetic macular oedema: DME is a distinct, parallel complication that can occur at any stage of retinopathy and requires separate diagnostic and treatment consideration.

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Word Breakdown

diabetic

=relating to diabetes mellitus (from Greek 'diabētēs' — siphon, referring to excessive urine flow)

retin-

=retina (from Latin 'rete' — net, referring to the vascular network)

-pathy

=disease or disorder (from Greek 'pathos' — suffering)

Literal Meaning: Disease of the retina associated with diabetes

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Abbreviations

DR=Diabetic Retinopathy — the overarching term for retinal microvascular disease attributable to diabetes mellitus

NPDR=Non-Proliferative Diabetic Retinopathy — the earlier stage, defined by the absence of retinal neovascularisation

PDR=Proliferative Diabetic Retinopathy — the advanced stage, defined by the presence of neovascularisation of the disc or elsewhere, or vitreous haemorrhage

DME=Diabetic Macular Oedema — fluid accumulation within the macula that may occur at any stage and is a leading cause of vision loss

ETDRS=Early Treatment Diabetic Retinopathy Study — the landmark trial that established the severity grading system and laser treatment evidence

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Synonyms & Variants

Diabetic fundus disease›Diabetic retinal disease›

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Category-Specific Context

Diabetic retinopathy is classified as a Disease because it is a defined pathological condition with recognised diagnostic criteria and a staging framework. The two-stage classification (NPDR and PDR) reflects the presence or absence of retinal neovascularisation, which is the defining feature of progression to proliferative disease. Diabetic macular oedema (DME) is considered in parallel to the NPDR/PDR spectrum, as it can occur at any stage and is assessed and treated according to macular involvement and visual impact. Severity grading within NPDR (mild, moderate, severe) is based on the ETDRS scale and informs follow-up intervals and treatment decisions.

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Clinical Context & Usage

CLINICAL SETTINGS

Ophthalmology Outpatient ClinicDiabetic Retina Screening ServiceGeneral Medicine WardEndocrinology ClinicEmergency Department (for acute vitreous haemorrhage or neovascular glaucoma)Primary Care

USAGE & DOCUMENTATION NOTES

In clinical documentation, the term is typically recorded as the stage and laterality, for example 'moderate NPDR right eye, mild NPDR left eye' or 'high-risk PDR both eyes'. Retinal screening reports commonly use the ETDRS or ICDR severity descriptors. When DME is present, it is documented separately with reference to centre involvement (centre-involving vs non-centre-involving) and visual acuity. Referral letters to ophthalmology should state the grade, the presence or absence of DME, and whether any sight-threatening feature (severe NPDR, PDR, or centre-involving DME) is present.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Chronic hyperglycaemia initiates a cascade of biochemical and cellular stresses in the retinal microvasculature, including increased flux through the polyol pathway, formation of advanced glycation end-products, activation of protein kinase C, and increased oxidative stress. These processes lead to pericyte loss, basement membrane thickening, and endothelial dysfunction, producing the hallmark lesion of early diabetic retinopathy: the microaneurysm. Progressive capillary non-perfusion and endothelial damage result in breakdown of the blood–retinal barrier, with intraretinal haemorrhage, hard exudate deposition, and macular oedema. Retinal ischaemia drives upregulation of vascular endothelial growth factor (VEGF) and other pro-angiogenic factors, which stimulate the formation of new vessels on the optic disc or elsewhere. These neovessels are friable and prone to haemorrhage, and their accompanying fibrovascular proliferation can exert traction on the retina, leading to tractional retinal detachment. Concurrent neurodegeneration and glial dysfunction contribute to retinal dysfunction independent of visible vascular lesions.

PRIMARY CAUSES

Chronic hyperglycaemia in type 1 diabetes mellitus

Sustained elevation of blood glucose activates multiple metabolic pathways in retinal capillary endothelial cells and pericytes, leading to microvascular damage and progressive retinal ischaemia.

Chronic hyperglycaemia in type 2 diabetes mellitus

Insulin resistance and hyperglycaemia produce the same microvascular and neurodegenerative retinal insult as in type 1 diabetes, often with a longer undiagnosed preclinical period.

Prolonged duration of diabetes

Cumulative exposure to hyperglycaemic and metabolic stress over time increases the probability and severity of retinal microvascular injury; prevalence rises substantially with diabetes duration.

Poor glycaemic control (elevated HbA1c)

Higher HbA1c levels correlate with greater cumulative glycaemic burden and more rapid progression of retinopathy.

Hypertension

Elevated blood pressure contributes to endothelial dysfunction and increased shear stress on retinal microvessels, promoting retinopathy incidence and progression.

Pregnancy in a woman with diabetes

Pregnancy-associated metabolic and haemodynamic changes can accelerate progression of existing retinopathy, particularly with rapid improvement in glycaemic control or pre-existing uncontrolled hypertension.

Renal disease (diabetic nephropathy)

Coexisting nephropathy is associated with more severe retinopathy, reflecting shared microvascular susceptibility and the influence of renal failure–related metabolic and blood pressure derangements.

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Epidemiology

Prevalence:Global prevalence of any diabetic retinopathy among people with diabetes is estimated at approximately 23% (95% CI 20–26), with proliferative diabetic retinopathy at 6% (95% CI 3–9), diabetic macular oedema at 5% (95% CI 4–6), and sight-threatening diabetic retinopathy at 11% (95% CI 9–14), based on retinal imaging studies published 2017–2024 across the seven IDF regions. Regional variation is reported, with higher prevalence estimates in parts of Africa and Southeast Asia.

Age Group:Retinopathy can occur at any age after the onset of diabetes; prevalence increases with diabetes duration. It is uncommon before puberty in type 1 diabetes. In type 2 diabetes, retinopathy may be present at the time of diagnosis because of a prolonged preclinical phase. The burden is highest in working-age adults, but older adults with long-standing diabetes also remain at risk.

Sex Predilection:Equal

Geographic Distribution:Diabetic retinopathy is a global problem, but prevalence estimates vary by region and are influenced by diabetes duration, glycaemic control, access to screening, and study methodology. Higher estimates have been reported in some African and Southeast Asian populations, while global pooled prevalence remains in the range of approximately 20–30% among people with diabetes.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 URGENT

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Sudden painless visual loss or a new shower of floaters in a person with diabetes raises concern for vitreous haemorrhage from proliferative diabetic retinopathy and requires urgent same-day ophthalmological assessment.
Severe ocular pain, redness, headache, and reduced vision in an eye with known or suspected proliferative diabetic retinopathy may indicate neovascular glaucoma; this is an emergency requiring immediate intraocular pressure assessment and ophthalmology involvement.
Any eye with severe NPDR or PDR, or with centre-involving DME, warrants prompt ophthalmology referral because these are sight-threatening features for which treatment has been shown to reduce the risk of severe visual loss; the finding itself does not confirm irreversible damage, but it mandates timely specialist evaluation.

URGENT EVALUATION TRIGGERS

Sudden onset of new floaters, flashes, or visual field loss in a person with diabetes
Sudden painless loss of vision, particularly with a known history of proliferative diabetic retinopathy
Severe ocular pain with redness and reduced vision, raising concern for neovascular glaucoma
Detection of severe NPDR, PDR, or centre-involving DME on screening or clinical examination

Contraindications & Precautions

CONTRAINDICATIONS

Do not delay referral for severe NPDR
PDR
or centre-involving DME while awaiting optimisation of systemic risk factors; ocular treatment decisions should not be deferred solely on the basis of suboptimal glycaemic control.
Do not perform panretinal photocoagulation in eyes with untreated severe macular oedema without considering the risk of exacerbating macular thickening; combined or sequenced management should be individualised by an ophthalmologist.
Do not use intravitreal anti-VEGF therapy without assessing relevant contraindications (e.g.
active or suspected ocular or periocular infection
known hypersensitivity) in accordance with the specific product label.

SPECIAL PRECAUTIONS

Rapid improvement in glycaemic control
particularly in the context of pregnancy or with insulin initiation
can be associated with early worsening of retinopathy; ophthalmic surveillance should be maintained during periods of intensive glycaemic intervention.
Pregnancy in a woman with diabetes requires early retinal assessment and closer follow-up
as retinopathy may progress during pregnancy.
Patients with diabetic retinopathy and coexisting nephropathy or uncontrolled hypertension warrant coordinated systemic and ocular management
as these factors influence progression.
When interpreting screening results
ensure that the grading system and referral thresholds used are appropriate to the local programme and that sight-threatening features are not overlooked because of media opacity or incomplete visualisation.

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Diabetic macular oedema — fluid accumulation within the macula causing central vision loss; may be centre-involving or non-centre-involving and can occur at any stage of retinopathy
Vitreous haemorrhage — bleeding from friable neovessels into the vitreous cavity
causing sudden visual loss or floaters; most characteristic of proliferative disease
Tractional retinal detachment — fibrovascular proliferation exerts traction on the retina
potentially causing macula-involving detachment and severe vision loss
Neovascular glaucoma — anterior segment neovascularisation obstructs aqueous outflow
causing severe intraocular pressure elevation and risk of optic nerve damage
Diabetic macular ischaemia — capillary non-perfusion of the macula contributing to vision loss that may be refractory to oedema-directed treatment

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Diabetic maculopathy

Often used interchangeably with diabetic macular oedema in clinical speech, but 'maculopathy' is a broader term that may encompass ischaemia, traction, and other macular pathology, whereas DME specifically denotes fluid accumulation; documentation should distinguish the two.

Hypertensive retinopathy

Can produce retinal haemorrhages, exudates, and cotton-wool spots that resemble diabetic retinopathy; the terms are distinct diagnoses with different systemic drivers and management priorities.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Hypertensive retinopathy

Key Distinguishing Feature: Bilateral, typically painless retinal changes with generalised arteriolar narrowing, arteriovenous nicking, and flame-shaped haemorrhages; systemic hypertension is the primary driver, and diabetic features such as microaneurysms may be absent or less prominent.

Central retinal vein occlusion

Key Distinguishing Feature: Usually unilateral; characterised by dilated and tortuous retinal veins, extensive flame-shaped haemorrhages in all four quadrants, and optic disc oedema; the unilateral presentation and venous engorgement help distinguish it from the typically bilateral diabetic retinopathy.

Ocular ischaemic syndrome

Key Distinguishing Feature: Unilateral or bilateral chronic ocular hypoperfusion, often with a history of carotid occlusive disease; findings may include midperipheral haemorrhages, narrowed arterioles, anterior segment inflammation, and neovascularisation, but the systemic vascular context and often asymmetric presentation differ from diabetic retinopathy.

Radiation retinopathy

Key Distinguishing Feature: History of external beam radiation exposure to the eye or orbit; retinal findings may include microaneurysms, haemorrhages, cotton-wool spots, and neovascularisation, but the temporal relationship to radiotherapy and the absence of diabetes are key distinguishing features.

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Clinical Pearls

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Diabetic retinopathy and diabetic macular oedema are parallel disease processes: a patient can have mild NPDR with vision-threatening DME, or advanced PDR with a normal macula. Staging the retinopathy alone does not capture the need for macular assessment; OCT is required when DME is suspected or when visual acuity is reduced.

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Proliferative diabetic retinopathy is defined by neovascularisation of the disc or elsewhere, or by vitreous haemorrhage, not by the absence or presence of microaneurysms or exudates. Once neovascularisation is present, the eye is considered at risk of vision-threatening events, and prompt ophthalmology referral is indicated even if visual acuity is currently normal.

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Pregnancy can accelerate the progression of diabetic retinopathy, particularly when glycaemic control is poor or when glucose control improves rapidly. Women with diabetes should have a retinal assessment early in pregnancy and follow-up intervals should be individualised by an ophthalmologist.

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The ETDRS '4-2-1 rule' is used to identify severe NPDR: haemorrhages in all four quadrants, venous beading in at least two quadrants, or intraretinal microvascular abnormalities in at least one quadrant. Severe NPDR carries a high risk of progression to PDR, and referral for specialist consideration of treatment or close surveillance is warranted.

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Intravitreal anti-VEGF therapy is a first-line treatment for centre-involving DME and an important option for proliferative disease, but it requires adherence to follow-up and carries a small risk of infectious and non-infectious endophthalmitis. Patients should be counselled about the need for prompt reporting of pain, redness, or visual decline after injection.

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Example Usage & SOAP

CLINICAL SENTENCE

""Fundoscopy revealed moderate non-proliferative diabetic retinopathy in the right eye and mild non-proliferative diabetic retinopathy in the left eye, with no evidence of centre-involving diabetic macular oedema on OCT; the patient was referred for diabetic retinopathy surveillance and optimisation of glycaemic and blood pressure control.""

IN A SOAP NOTE

S: A 58-year-old man with a 12-year history of type 2 diabetes attends for annual retinal screening. He reports no visual symptoms. O: Visual acuity 6/6 bilaterally. Dilated fundus examination shows microaneurysms, dot-blot haemorrhages, and hard exudates in the right eye, with findings consistent with moderate NPDR; the left eye shows microaneurysms only. OCT macula demonstrates no centre-involving oedema. HbA1c 8.1%; BP 148/88 mmHg. A: Moderate non-proliferative diabetic retinopathy right eye, mild non-proliferative diabetic retinopathy left eye, without centre-involving diabetic macular oedema. P: Continue 6-monthly retinal surveillance per local protocol; reinforce glycaemic and blood pressure targets with primary care; advise urgent review if visual symptoms develop.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for diabetic retinopathy: (1) Hypertensive retinopathy — check blood pressure control and look for arteriolar narrowing, arteriovenous nicking, and flame-shaped haemorrhages; (2) Central retinal vein occlusion — usually unilateral, with dilated tortuous veins and extensive four-quadrant haemorrhages; (3) Ocular ischaemic syndrome — consider in patients with carotid disease, often with asymmetric findings and anterior segment involvement; (4) Radiation retinopathy — obtain a history of prior ocular or orbital radiotherapy. The presence of bilateral microaneurysms, hard exudates, and a known history of diabetes favours diabetic retinopathy, but coexisting hypertensive or veno-occlusive disease should be considered when findings are atypical or asymmetric.

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Classifications & Scoring

GRADING SYSTEM

ETDRS Diabetic Retinopathy Severity Scale

The Early Treatment Diabetic Retinopathy Study scale grades retinopathy from level 10 (no retinopathy) through levels 20–53 for non-proliferative disease and levels 60–85 for proliferative disease, based on standard fundus photographs and defined lesions. It remains a reference standard for clinical research and informs severity classification in clinical practice.

GRADING SYSTEM

International Clinical Diabetic Retinopathy (ICDR) Severity Scale

A simplified scale derived from ETDRS that classifies retinopathy as no apparent retinopathy, mild NPDR (microaneurysms only), moderate NPDR (more than microaneurysms but less than severe NPDR), severe NPDR (any of: >20 intraretinal haemorrhages in each of 4 quadrants, venous beading in ≥2 quadrants, or IRMA in ≥1 quadrant), and PDR (neovascularisation or vitreous/pre-retinal haemorrhage). It is widely used in screening and clinical communication.

STAGING SCALE

ETDRS 13-level severity scale

A detailed research-oriented scale that divides diabetic retinopathy into 13 levels ranging from absence of retinopathy to severe vitreous haemorrhage, used to describe overall retinopathy severity and change over time in clinical studies.

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Prognosis

SHORT-TERM OUTCOME

Short-term visual prognosis depends on the stage at detection and the presence of DME. Mild to moderate NPDR without centre-involving DME typically does not cause immediate visual loss but requires scheduled surveillance. Severe NPDR and PDR carry a substantial short-term risk of progression to sight-threatening events if untreated; timely panretinal photocoagulation or anti-VEGF therapy reduces this risk. Centre-involving DME can cause subacute visual decline and requires prompt ophthalmic assessment and treatment.

LONG-TERM PROGNOSIS

Long-term outcomes are strongly influenced by glycaemic and blood pressure control, diabetes duration, and access to regular screening and timely treatment. Many people with diabetes develop some degree of retinopathy over decades, but severe vision loss is preventable in a large proportion when sight-threatening disease is detected and managed appropriately. Proliferative disease and chronic macular oedema remain important causes of permanent visual impairment, particularly where treatment is delayed or unavailable.

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References & Coding

ICD-10 DIAGNOSTIC CODE

E14.3

LITERATURE CITATIONS & GUIDELINES

[1]Diabetic retinopathy. BMJ Best Practice. Evidence last reviewed September 2026. Topic last updated July 2026.

[2]National Institute for Health and Care Excellence. Diabetic retinopathy: management and monitoring. NICE guideline NG242. August 2024. https://www.nice.org.uk/guidance/ng242

[3]American Academy of Ophthalmology. Diabetic Retinopathy Preferred Practice Pattern. 2024.

[4]Owens DR, Gurudas S, Sivaprasad S, et al. IDF diabetes Atlas: A worldwide review of studies utilizing retinal photography to screen for diabetic retinopathy from 2017 to 2024 inclusive. Diabetes Res Clin Pract. 2025;226:112346. doi:10.1016/j.diabres.2025.112346

[5]Early Treatment Diabetic Retinopathy Study Research Group. Grading diabetic retinopathy from stereoscopic color fundus photographs—an extension of the modified Airlie House classification. ETDRS report number 10. Ophthalmology. 1991;98(5 Suppl):786-806.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.