Fundoscopy in Systemic Disease
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Direct answer
Fundoscopy is the direct examination of the optic disc, retinal vessels and macula, and it reveals the retinal signs of hypertension, diabetes, raised intracranial pressure and endocarditis. Hypertensive retinopathy is graded by the Keith-Wagener-Barker system, and diabetic retinopathy progresses from microaneurysms to neovascularisation. Papilloedema, bilateral swelling of the optic disc, is the sign that signals raised intracranial pressure.
What you must remember
- Keith-Wagener-Barker grading: grade I is arteriolar narrowing, grade II adds arteriovenous nipping, grade III adds flame haemorrhages, cotton wool spots and hard exudates, and grade IV is papilloedema.
- Arteriovenous nipping: the vein looks compressed where an arteriole crosses it, a marker of chronic hypertension and arteriolar sclerosis.
- Microaneurysms: the earliest sign of diabetic retinopathy, seen as small red dots, with dot and blot haemorrhages following in non-proliferative disease.
- Proliferative diabetic retinopathy: new vessels on the disc or elsewhere carry a risk of vitreous haemorrhage and tractional detachment, managed with panretinal photocoagulation or anti-VEGF agents.
- Papilloedema: bilateral disc swelling with blurred margins, venous engorgement and loss of spontaneous venous pulsation, with visual acuity preserved in the early stage.
- Roth spots: retinal haemorrhages with pale centres, classically linked to infective endocarditis but also seen in anaemia, leukaemia and HIV.
- Hollenhorst plaque: a refractile cholesterol embolus at an arteriolar bifurcation, pointing to atheroma in the carotid or aortic system.
- Cherry-red spot: a red fovea against a pale oedematous retina, seen in central retinal artery occlusion and lysosomal storage disorders such as Tay-Sachs disease.
A systematic sequence for reading the fundus
A severely hypertensive woman with a headache is referred for fundoscopy, and the findings will shape the next investigations. A consistent order of examination prevents missed signs.
- Start with the optic disc: Note its colour, margins and cup-disc ratio, where a ratio above about 0.5 raises suspicion of glaucoma. Blurred margins with swelling point to papilloedema rather than pseudopapilloedema from drusen.
- Examine the arteries and veins: Look for arteriolar narrowing and arteriovenous nipping at each crossing. These changes mark chronic hypertension and are graded by the Keith-Wagener-Barker system.
- Scan for haemorrhages and exudates: Flame-shaped haemorrhages, cotton wool spots and hard exudates signal grade III hypertensive change, while dot and blot haemorrhages with microaneurysms point to diabetes.
- Trace the macula and periphery: A macular star of hard exudates suggests severe hypertension or long-standing papilloedema, while neovascularisation is searched for on the disc and beyond the vascular arcades. New fibrovascular vessels raise the risk of vitreous haemorrhage.
- Correlate with the systemic picture: Papilloedema calls for neuroimaging before any lumbar puncture, and Roth spots prompt blood cultures for endocarditis. The fundus rarely settles a diagnosis on its own.
Where the examiner tests your fundus recall
Fundus questions usually test whether you can link one retinal sign to its systemic cause.
- Trap: calling any swollen disc papilloedema Correct: papilloedema is bilateral with raised intracranial pressure, whereas unilateral disc swelling with reduced acuity and pain points to optic neuritis.
- Trap: attributing every cotton wool spot to hypertension Correct: these spots also occur in diabetes, HIV, lupus and retinal vein occlusion, so the systemic history decides the cause.
- Trap: treating Roth spots as diagnostic of endocarditis Correct: they are non-specific and occur in anaemia, leukaemia and HIV, so blood cultures are needed to confirm the cause.
Frequently asked questions
Which fundus finding distinguishes papilloedema from optic neuritis?
Papilloedema is bilateral disc swelling with preserved visual acuity in the early stage, whereas optic neuritis usually affects one eye with pain and reduced acuity or colour vision. Papilloedema also shows venous engorgement and blurred disc margins, and it signals raised intracranial pressure.
What is the Keith-Wagener-Barker classification of hypertensive retinopathy?
The Keith-Wagener-Barker classification grades hypertensive retinopathy from grade I, with mild arteriolar narrowing, to grade IV, with papilloedema. Grade II adds arteriovenous nipping, and grade III adds flame-shaped haemorrhages, cotton wool spots and hard exudates.
What is the earliest fundus sign of diabetic retinopathy?
Microaneurysms are the earliest fundus sign of diabetic retinopathy, appearing as small red dots, mostly in the posterior pole. Dot and blot haemorrhages, hard exudates and venous beading follow in the non-proliferative stage, while neovascularisation marks the proliferative stage.
Which retinal finding is classic for infective endocarditis?
Roth spots, retinal haemorrhages with pale or white centres, are the classic retinal finding of infective endocarditis. They also occur in anaemia, leukaemia and HIV, so the diagnosis of endocarditis must be confirmed with blood cultures and echocardiography.
What does a cherry-red spot at the macula suggest?
A cherry-red spot at the macula suggests central retinal artery occlusion, where the foveal region appears red against a pale, oedematous retina. It is also a feature of lysosomal storage disorders such as Tay-Sachs disease.