Microvascular retinal disease from chronic hyperglycemia — leading cause of new-onset blindness in working-age adults.
Also known as: diabetic retinopathy, DR, NPDR, PDR, non-proliferative diabetic retinopathy, proliferative diabetic retinopathy, diabetic macular edema, DME
Overview
Microvascular complication of diabetes mellitus characterized by progressive retinal microaneurysms, hemorrhages, exudates, ischemia, and ultimately neovascularization. Classified as non-proliferative (NPDR — mild, moderate, severe) and proliferative (PDR — new vessels at the disc, NVD, or elsewhere, NVE). Diabetic macular edema (DME) — fluid in the central macula — can occur at any stage.
Epidemiology
Leading cause of new-onset blindness in US adults aged 20-74. Nearly all patients with type 1 diabetes for >20 years and most with type 2 develop some degree of retinopathy. Prevalence of vision-threatening retinopathy ~5-10% of diabetic patients.
Try two board-style Diabetic Retinopathy questions
Real questions from the FirstPassPA bank, with the full explanation. Pick an answer — no signup, no email.
Question 1EENTEasy
A 55-year-old diabetic female has fundoscopy showing dot/blot hemorrhages, hard exudates, microaneurysms, and cotton wool spots bilaterally without neovascularization. A circinate hard exudate ring surrounds the right fovea, with optical coherence tomography (OCT) showing 310 micron central subfield thickness. Visual acuity 20/50 OD. Which of the following is the most likely diagnosis?
AModerate non-proliferative retinopathy without macular edema
BSevere non-proliferative retinopathy without macular edema
EMild non-proliferative retinopathy without macular edema
Why Non-proliferative retinopathy, center-involving macular edema is correct
Center-involving diabetic macular edema (CI-DME) is defined as fluid within 500 microns of the foveal center and is the most vision-threatening form
Optical coherence tomography (OCT) is the gold standard for diagnosis; this patient's central subfield thickness of 310 microns confirms macular edema
The circinate hard exudate ring surrounding the fovea and visual acuity of 20/50 OD are consistent with center-involving disease
Absence of neovascularization rules out proliferative diabetic retinopathy; cotton wool spots and hard exudates exceed the mild category, and the thickened central subfield on OCT places the edema at the foveal center rather than outside it
Why the others are wrong
Mild non-proliferative retinopathy without macular edema — limited to a few microaneurysms; cotton wool spots, hard exudates, and macular edema place this in a more advanced category (premature closure)
Severe non-proliferative retinopathy without macular edema — the hemorrhages and cotton wool spots may prompt a severity-only answer, but the circinate hard exudate ring around the fovea and a central subfield thickness of 310 microns on OCT establish macular edema, the vision-threatening finding here (premature closure)
Non-proliferative retinopathy, non-center-involving macular edema — macular edema is present but here involves the foveal center on OCT with VA loss (confused-with non-center-involving)
Moderate non-proliferative retinopathy without macular edema — with no 4-2-1 features described, the hemorrhages, hard exudates, and cotton wool spots do fit a moderate severity grade, but a severity grade alone misses the circinate hard exudate ring around the fovea and the 310-micron central subfield thickness on OCT that establish center-involving macular edema (premature closure)
Additional high-yield points
Treatment for CI-DME: intravitreal anti-vascular endothelial growth factor (anti-VEGF) first-line
DRCR.net Protocol T: aflibercept is superior when visual acuity is 20/50 or worse
Systemic targets: A1c <7%, BP <130/80, statin therapy for hard exudates
Severe NPDR follows the 4-2-1 rule: intraretinal hemorrhages in all four quadrants, venous beading in two or more quadrants, or intraretinal microvascular abnormalities (IRMA) in one or more quadrants
Question 2EENTMedium
A 58-year-old man with a 22-year history of type 2 diabetes presents with sudden, painless loss of vision in his right eye that began this morning, preceded by a shower of new floaters. His most recent A1c was 9.4%, and he has not had a dilated eye exam in 6 years. Visual acuity in the right eye is limited to counting fingers. On attempted fundoscopy, a dense vitreous hemorrhage completely obscures the view of the retina. Which of the following is the most appropriate next diagnostic test?
AB-scan ocular ultrasonography
BOptical coherence tomography
CA-scan ultrasound biometry
DRetinal fluorescein angiography
EWide-field fundus photography
Reveal answer & full explanation
Correct answer: A — B-scan ocular ultrasonography
AB-scan ocular ultrasonography✓
BOptical coherence tomography
CA-scan ultrasound biometry
DRetinal fluorescein angiography
EWide-field fundus photography
Why B-scan ocular ultrasonography is correct
A dense vitreous hemorrhage obscures the fundus, so any test that depends on a clear optical view of the retina is useless until the media clears.
B-scan ultrasound does not require an optical window; it images through the opaque vitreous to detect a tractional retinal detachment, the feared complication of proliferative diabetic retinopathy that changes management (urgent vitrectomy) versus simple observation of the hemorrhage.
AAO guidance: when media opacity prevents fundus visualization in a diabetic with vitreous hemorrhage, B-scan is the study of choice to rule out retinal detachment.
Why the others are wrong
Optical coherence tomography quantifies macular thickness and diabetic macular edema but requires a clear optical path to the retina; it cannot image through a dense vitreous hemorrhage.
Retinal fluorescein angiography maps capillary nonperfusion, leakage, and neovascularization, but the dye and camera both need an unobscured retinal view that the hemorrhage prevents.
Wide-field fundus photography is the primary teleretinal screening tool for asymptomatic patients, but it is a photographic image of the fundus and is blocked by the same opaque media.
A-scan ultrasound biometry — like B-scan it uses ultrasound and is not blocked by vitreous blood, but A-scan biometry is a one-dimensional echo trace used mainly to measure axial length for intraocular lens calculations; it does not produce the two-dimensional cross-sectional image that B-scan uses to show whether the retina is detached behind the blood.
That's 2. Get 7,700+ more.
Unlock the full FirstPassPA bank: 7,700+ board-style questions, flashcards, and an AI tutor that explains every answer. Your 7-day free trial includes everything, and there's no credit card required.
You've read your 2 free diagnosis previews. Create your free account to unlock the full Diabetic Retinopathy outline — plus all 514 diagnoses, 7,700+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
Pregnancy (can accelerate progression — exam at first prenatal visit)
Renal disease (proteinuria)
Smoking
Anemia, sleep apnea
Rapid intensive glycemic correction in long-standing poor control (transient worsening)
Pathophysiology
Chronic hyperglycemia drives advanced glycation end-product formation, polyol pathway flux, protein kinase C activation, and oxidative stress. These damage retinal capillary pericytes and endothelial cells, leading to microaneurysm formation, increased vascular permeability (edema and exudates), capillary nonperfusion (ischemia), and upregulation of VEGF. VEGF drives macular edema and, when ischemia is widespread, proliferative neovascularization. New vessels are fragile and grow along the posterior hyaloid, causing vitreous hemorrhage and tractional retinal detachment.
Clinical presentation
Symptoms
Often ASYMPTOMATIC until advanced or DME develops — emphasizes screening
Blurred or fluctuating vision (often with glycemic swings)
Floaters or sudden vision loss — vitreous hemorrhage from PDR
Curtain over vision — tractional retinal detachment
Central blurring or distortion — diabetic macular edema
PDR: neovascularization of the disc (NVD) or elsewhere (NVE), preretinal/vitreous hemorrhage, fibrovascular proliferation, tractional retinal detachment
DME: retinal thickening within 1 disc diameter of fovea; circinate exudates; cysts on OCT; center-involving DME = thickening of the OCT central subfield (1-mm zone within ~500 µm of the foveal center), often with reduced acuity; non-center-involving DME spares that zone
Reduced visual acuity in severe disease
Rubeosis iridis and neovascular glaucoma in advanced ischemia
Classic findings
Dot-blot hemorrhages with hard exudates and microaneurysms in a diabetic; neovascularization of the disc (NVD) in PDR.
Differential diagnosis
Hypertensive retinopathy — AV nicking, copper/silver wiring, flame hemorrhages; microaneurysms can occur in moderate disease, so arteriolar changes and the history (HTN vs DM) discriminate; disc edema in malignant HTN; control BP
Retinal vein occlusion (CRVO/BRVO) — Sudden vision loss, sectoral or diffuse hemorrhages in distribution of occluded vein
ADA / AAO screening: dilated exam at diagnosis in type 2 DM and within 5 years of diagnosis in type 1 (and at puberty), then annually (or every 1-2 years if no retinopathy and good glycemic control). Pregnant diabetic patients: exam in first trimester and as indicated.
Labs
A1c, lipid panel, BMP, urine albumin-creatinine — for diabetic care, not specific to DR diagnosis
Diabetic macular edema (non-center-involving) — focal/grid laser per ETDRS
Intravitreal corticosteroid implant — dexamethasone (Ozurdex), fluocinolone (Iluvien) — for DME refractory to anti-VEGF or pseudophakic patients; cataract and IOP-rise risk
Proliferative DR — panretinal photocoagulation (PRP) — ablates peripheral ischemic retina to reduce VEGF drive (DRS); high-risk PDR is a class I indication
Anti-VEGF — non-inferior to PRP for PDR over 2 years (Protocol S), and preferred when DME coexists
Vitrectomy for non-clearing vitreous hemorrhage, tractional retinal detachment threatening macula, or combined tractional-rhegmatogenous detachment (DRVS)
Cataract progression and earlier need for cataract surgery
Worsened DR after rapid glycemic correction (transient — emphasize gradual normalization in chronically uncontrolled patients)
PANCE pearls
Early DR is silent — annual dilated exams or telehealth retinal photos are essential per ADA guidelines.
Macular edema can occur at any stage of DR — measure with OCT, not just slit-lamp.
PROLIFERATIVE DR = new vessels (NVD or NVE) and is the indication for PRP and/or anti-VEGF.
Anti-VEGF is now first-line for center-involving DME and is non-inferior to PRP for PDR, particularly when DME coexists (Protocol S).
Pregnancy can rapidly accelerate DR — screen at first prenatal visit and as indicated; gestational diabetes alone does not require retinal screening.
Fenofibrate slowed retinopathy progression independently of lipid effects in ACCORD Eye and FIELD — consider in patients with DR and dyslipidemia.
References
ADA 2026 — American Diabetes Association Professional Practice Committee. 12. Retinopathy, Neuropathy, and Foot Care: Standards of Care in Diabetes—2026. Diabetes Care 2026;49(Suppl 1):S261-S276
AAO 2024 — American Academy of Ophthalmology (Lim JI et al.). Diabetic Retinopathy Preferred Practice Pattern. Ophthalmology 2025;132(4):P75-P162
DCCT/EDIC — DCCT Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes. NEJM 1993;329(14):977-986
ETDRS — Early Treatment Diabetic Retinopathy Study Research Group. Photocoagulation for diabetic macular edema. ETDRS Report Number 1. Arch Ophthalmol 1985;103(12):1796-1806
Protocol S — Gross JG et al. Panretinal photocoagulation vs intravitreous ranibizumab for proliferative diabetic retinopathy. JAMA 2015;314(20):2137-2146
Practice EENT questions on FirstPassPA
Turn this outline into retention. 7,700+ board-style questions with an AI tutor that explains every answer — free to start, no card required.
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.