Lucan · Conditions

Acute vision loss

Australian guidance: HealthPathways WA (Vision Loss / Red Eye) + RANZCO position statements + eTG Rheumatology (GCA) + RACGP clinical guidance + Stroke Foundation AU (TIA pathway)

1. Definition and epidemiology

Acute vision loss is a sudden reduction in visual acuity or visual field, evolving over seconds to days, in one or both eyes. It is worked up as an ophthalmic and sometimes neurological emergency, because several of its causes share a narrow treatment window with cerebral stroke or carry a high risk of imminent, bilateral, and permanent blindness if the diagnosis is missed. The single most useful bedside branch point is whether the vision loss is painless or painful: painless acute vision loss points toward vascular occlusion, vitreoretinal traction, or optic nerve/pathway disease, while painful vision loss points toward anterior segment or pressure-related pathology such as acute angle closure glaucoma, keratitis, uveitis, or endophthalmitis (each covered elsewhere). This topic covers the major painless causes — central retinal artery occlusion (CRAO), central retinal vein occlusion (CRVO), retinal detachment and its precursor posterior vitreous detachment (PVD), vitreous haemorrhage, optic neuritis, and amaurosis fugax — together with giant cell arteritis (GCA), the systemic vasculitis that can present as any of several of these and is the single diagnosis every clinician is trained never to miss.

Retinal artery occlusion is rare (on the order of 1 to 2 per 100,000 per year) but devastating; retinal vein occlusion is considerably more common and rises steeply with age, hypertension, and diabetes. Retinal detachment has an annual incidence of roughly 1 in 10,000, with strong predisposition in high myopes, after cataract surgery, and after blunt or penetrating trauma. Optic neuritis typically affects adults aged 20 to 45, is more common in women, and is frequently the presenting feature of multiple sclerosis (MS). GCA is a disease of patients over 50, peaks in the seventh and eighth decades, is more common in women, and has its highest incidence in populations of Northern European ancestry, though it is seen across the Australian population and must be considered in any older patient with acute monocular vision loss regardless of background.

2. Pathophysiology

CRAO is the ophthalmic equivalent of an ischaemic stroke: the retina is exquisitely sensitive to interrupted perfusion and tolerates only around 90 to 100 minutes of complete ischaemia before irreversible infarction of the inner retinal layers. Most cases are embolic, from carotid atherosclerosis or a cardiac source (analogous to embolic cerebral stroke), a minority are thrombotic or vasospastic, and a clinically critical subset is arteritic, caused by GCA occluding the ophthalmic artery or its branches through granulomatous vasculitis of the vessel wall. Because arteritic and non-arteritic CRAO are clinically difficult to distinguish at first presentation and carry very different management urgency, every CRAO in a patient over 50 is treated as possible GCA until proven otherwise.

CRVO arises where the central retinal vein crosses the central retinal artery at or just posterior to the lamina cribrosa; the two vessels share a common adventitial sheath at this point, and atherosclerotic thickening of the artery compresses the thinner-walled vein, precipitating thrombosis. Risk factors mirror those for atherosclerotic disease generally — hypertension, diabetes, hyperlipidaemia — plus glaucoma and hyperviscosity states. The resulting venous stasis produces diffuse intraretinal haemorrhage and macular oedema, and in the ischaemic subtype extensive capillary non-perfusion drives retinal neovascularisation.

Retinal detachment is separation of the neurosensory retina from the underlying retinal pigment epithelium; the rhegmatogenous form (by far the most common) begins with a retinal tear that lets liquefied vitreous track beneath the retina. Tears are typically caused by PVD, the age-related separation of the vitreous gel from the retina that becomes near-universal with advancing age and is accelerated by myopia, trauma, and cataract surgery: as the vitreous collapses forward, tractional pull at points of firm vitreoretinal adhesion (classically at the vitreous base and around retinal blood vessels) can tear the retina and, if a vessel is torn, cause vitreous haemorrhage at the same time. Most PVD is benign and self-limiting, but roughly 10 to 15% of patients with acute, symptomatic PVD are found to have a retinal tear on examination, which is why every new PVD requires a dilated peripheral retinal examination rather than reassurance alone. Tractional retinal detachment (from fibrovascular membranes in proliferative diabetic retinopathy) and exudative detachment (from choroidal tumour or severe uveitis, without a break) are less common variants.

Vitreous haemorrhage results either from bleeding at the site of a retinal tear during acute PVD, or from rupture of abnormal, fragile new vessels in proliferative diabetic retinopathy or ischaemic CRVO; less commonly it follows trauma. Optic neuritis is autoimmune-mediated inflammatory demyelination of the optic nerve, most often idiopathic or the first presentation of MS (roughly half of MS patients develop optic neuritis at some point in their disease course), with more severe or bilateral presentations raising suspicion for neuromyelitis optica spectrum disorder (aquaporin-4 antibody) or MOG-antibody disease. Amaurosis fugax is transient monocular retinal ischaemia, almost always embolic from ipsilateral carotid stenosis or a cardiac source, and is the retinal circulation's equivalent of a cerebral transient ischaemic attack (TIA), carrying the same downstream stroke risk. GCA itself is a granulomatous large- and medium-vessel vasculitis of the cranial branches of the aorta; when it involves the posterior ciliary arteries supplying the optic nerve head it causes arteritic anterior ischaemic optic neuropathy (AAION), the most common sight-threatening manifestation, though arteritic CRAO also occurs. Without treatment, involvement of the fellow eye typically follows within days, which underlies the extreme management urgency described below.

3. Clinical presentation and diagnostic criteria

CRAO presents as sudden, profound, painless monocular vision loss, often to counting fingers or worse, with a relative afferent pupillary defect (RAPD). Fundoscopy classically shows a pale, oedematous retina with a cherry-red spot at the fovea (where the thin retina lets the underlying choroidal circulation show through) and segmentation ("boxcarring") of blood in the retinal vessels; an embolus (Hollenhorst plaque) may be visible at a vessel bifurcation.

CRVO produces sudden or subacute painless vision loss of variable severity — mild in the non-ischaemic form, severe with a dense RAPD in the ischaemic form — with a fundus described as "blood and thunder": diffuse flame and blot haemorrhages in all four quadrants, dilated tortuous veins, cotton wool spots, and disc swelling.

PVD announces itself with new floaters and flashes (photopsia) as the separating vitreous mechanically stimulates the retina; this is the symptom complex that must trigger urgent examination, because it is clinically indistinguishable from the onset of a retinal tear until a dilated peripheral examination is done. Retinal detachment itself typically follows with a dense, painless shadow or curtain progressing across part of the visual field, corresponding to the area of detached retina; whether the macula remains attached ("macula-on") or is already involved ("macula-off") is the key prognostic and urgency marker, since central acuity is preserved in the former and already lost in the latter.

Vitreous haemorrhage presents as sudden painless floaters, cobwebs, or a shower of red spots, sometimes progressing to a marked haze or near-total vision loss if dense; the red reflex is diminished or absent, and a dense haemorrhage can obscure the fundus view entirely, making an underlying retinal detachment impossible to exclude clinically.

Optic neuritis evolves over hours to days with unilateral vision loss, dyschromatopsia (red desaturation) that is often disproportionate to the acuity loss, an RAPD, and pain on eye movement from traction on the inflamed nerve sheath by the extraocular muscles. Fundoscopy may be normal if the inflammation is retrobulbar ("the patient sees nothing and the doctor sees nothing") or show disc swelling (papillitis) if the inflammation is anterior.

Amaurosis fugax presents as transient, painless, monocular vision loss classically described as a curtain descending, lasting seconds to a few minutes and resolving completely, with a normal eye examination between episodes; it is taken exactly as seriously as a cerebral TIA.

GCA should be actively screened for in any patient over 50 with acute visual symptoms: new headache (often temporal), scalp tenderness, jaw claudication on chewing, a tender, thickened, or pulseless temporal artery, systemic features such as fever, malaise, and weight loss, and coexisting polymyalgia rheumatica (proximal girdle pain and stiffness) in up to half of cases. Visual symptoms include amaurosis fugax preceding permanent loss in a substantial proportion, diplopia, and sudden severe vision loss from AAION, in which fundoscopy shows a pale, chalky-white swollen disc, in contrast to the hyperaemic disc swelling of non-arteritic AION. The 2022 ACR/EULAR classification criteria for GCA combine age ≥50, cranial symptoms, elevated inflammatory markers, and temporal artery abnormality on examination, imaging, or biopsy, and are useful for structuring the clinical suspicion even though they were designed for research classification rather than as a bedside diagnostic rule.

4. Investigations and AU-specific details

Any acute, unexplained vision loss warrants same-day ophthalmology assessment; the specific pathway then diverges by cause. CRAO is investigated and managed as an ocular stroke: carotid duplex ultrasound, ECG, and echocardiography to identify an embolic source, together with fasting lipids and glucose, mirror the standard AU stroke/TIA work-up, and HealthPathways WA and Australian stroke services increasingly route acute CRAO through the hyperacute stroke pathway for same-day assessment given the shared pathophysiology with cerebral infarction. This routing is for rapid embolic-source work-up and secondary prevention, not for reperfusion therapy: the EAGLE trial (Schumacher et al., Ophthalmology 2010) tested local intra-arterial fibrinolysis, not IV alteplase, against conservative treatment and found no benefit with a high rate of adverse effects, leading to abandonment of intra-arterial thrombolysis for CRAO; a small dedicated IV tPA trial (Chen et al., Stroke 2011) was separately terminated early after only 16 patients over safety concerns, and the larger, more recent THEIA trial (Lancet Neurology, 2025) found IV alteplase given within 4.5 hours conferred no significant visual benefit over aspirin. So neither intra-arterial nor intravenous thrombolysis is current standard Australian practice for CRAO. FBE, ESR, and CRP are mandatory in every CRAO patient over 50 specifically to screen for GCA, because an arteritic cause changes management from vascular risk reduction to emergency corticosteroids.

CRVO investigation includes fundus fluorescein angiography to grade the degree of capillary non-perfusion and classify ischaemic versus non-ischaemic disease, optical coherence tomography (OCT) of the macula to quantify oedema, and screening for hypertension, diabetes, and dyslipidaemia; a thrombophilia screen is reserved for patients under 50 without conventional vascular risk factors.

New PVD symptoms (flashes and floaters) require an urgent dilated fundus examination with indirect ophthalmoscopy and scleral depression to search the peripheral retina for a tear, consistent with RANZCO and HealthPathways WA referral guidance; if the view is obscured by vitreous haemorrhage, B-scan ultrasound is used to look for an underlying retinal detachment that cannot be seen directly.

Optic neuritis is investigated with MRI of the brain and orbits with gadolinium contrast, which shows optic nerve enhancement and, critically, quantifies the burden of demyelinating white matter lesions — the strongest predictor of subsequent conversion to clinically definite MS, a relationship first established in the Optic Neuritis Treatment Trial and still the basis of Australian practice. Aquaporin-4 and MOG antibody serology are added where features are atypical (bilateral, severe, poorly recovering, or in an older patient), and lumbar puncture for oligoclonal bands is used selectively.

Amaurosis fugax is investigated exactly as a TIA: urgent carotid duplex ultrasound, ECG or Holter monitoring, and echocardiography, with referral to a TIA or stroke clinic within 24 hours per Stroke Foundation Australia and AU state TIA pathway guidance, regardless of the calculated ABCD2 score, given the established stroke risk of a retinal TIA.

GCA investigation begins with ESR and CRP, both raised in the great majority of cases, though a normal ESR does not exclude the diagnosis and treatment should never be withheld while awaiting results. FBE may show a normocytic anaemia and reactive thrombocytosis. Temporal artery biopsy remains the traditional reference standard, but colour duplex ultrasound of the temporal (and, where available, axillary) arteries, looking for the non-compressible "halo sign," is increasingly used in Australian rheumatology practice as an accessible, non-invasive first-line test, reflecting the shift embedded in the 2022 ACR/EULAR criteria. Critically, biopsy or ultrasound is arranged after treatment has started, not before: diagnostic changes on biopsy typically persist for one to two weeks after corticosteroids are begun, so imaging or biopsy timing must never be allowed to delay treatment of suspected GCA with visual symptoms.

5. Management

CRAO has no reliably effective treatment once infarction has occurred, and in Australian practice this is the case for the great majority of presentations because patients rarely arrive within the roughly 90 to 100 minute perfusion window. Where a patient does present hyperacutely, manoeuvres such as ocular massage, anterior chamber paracentesis, and intraocular pressure–lowering agents have limited evidence but may be attempted to try to dislodge an embolus or extend the ischaemic window; more important in practice is immediate entry into the stroke pathway for secondary prevention, because the embolic source threatening the eye equally threatens the brain. If GCA is suspected, high-dose corticosteroids are started immediately regardless of any other CRAO work-up.

CRVO with macular oedema is treated with intravitreal anti-VEGF injections (aflibercept, ranibizumab, or off-label bevacizumab), all PBS-subsidised for this indication in Australia and first-line over other options; an intravitreal dexamethasone implant is an alternative, particularly in pseudophakic patients or those in whom steroid response can be closely monitored. Panretinal photocoagulation is reserved for ischaemic CRVO complicated by retinal or iris neovascularisation, to prevent or treat neovascular glaucoma. Regular ophthalmology review is required to watch for this complication, classically within the first 100 days after an ischaemic event (the so-called "100-day glaucoma" window).

Retinal detachment management is dictated by macular status. A macula-on detachment is a same-day surgical emergency, because repair within roughly 24 hours preserves central vision that is still intact; a macula-off detachment still requires urgent repair, generally within about a week, but the precise timing is less time-critical because central vision is already lost and the overall visual prognosis is more guarded regardless of small delays beyond that window. Surgical options — pneumatic retinopexy, scleral buckle, and pars plana vitrectomy — are selected according to the location, extent, and cause of the detachment.

Vitreous haemorrhage without an identifiable detachment is usually managed conservatively at first, with head elevation, avoidance of anticoagulant or antiplatelet medications where clinically feasible, and observation for spontaneous clearing, once B-scan ultrasound has excluded an underlying retinal detachment. Vitrectomy is reserved for dense, non-clearing haemorrhage, particularly where it prevents treatment of underlying proliferative retinopathy or where detachment is present or strongly suspected.

Optic neuritis with significant vision loss is treated with high-dose intravenous methylprednisolone, typically 1 g daily for three days, which hastens visual recovery without changing the final visual outcome or the long-term risk of conversion to MS, per the Optic Neuritis Treatment Trial evidence still followed in Australian neuro-ophthalmology practice; oral prednisolone alone is specifically avoided as monotherapy, since trial evidence showed it increased the risk of recurrence when used without preceding IV steroid. Neurology involvement and consideration of disease-modifying therapy follow where MRI shows a high burden of demyelinating lesions.

Amaurosis fugax is managed on the TIA pathway: immediate antiplatelet therapy (aspirin) pending specialist review, urgent carotid endarterectomy or stenting where significant (roughly 50 to 70% or greater) symptomatic carotid stenosis is confirmed, and aggressive risk factor modification of blood pressure, lipids, glucose, and smoking.

GCA management is a clinical emergency: once GCA is clinically suspected, especially with any visual symptom, high-dose corticosteroids are started the same day, ideally within the hour, and are never delayed for biopsy or imaging confirmation. Australian rheumatology practice uses oral prednisolone 40 to 60 mg daily (roughly 1 mg per kg) for GCA without visual involvement, stepping up to IV methylprednisolone 500 mg to 1 g daily for three days where vision loss has occurred or the fellow eye is threatened, in an attempt to salvage vision, followed by a prolonged oral prednisolone taper. Tocilizumab, an IL-6 receptor inhibitor PBS-listed in Australia for GCA, is used early as a steroid-sparing option, particularly in relapsing or refractory disease or where significant corticosteroid-related toxicity is anticipated, to reduce cumulative glucocorticoid exposure (the exact current PBS authority wording should be verified in a future revision before asserting first-line use as settled practice). Low-dose aspirin is often added to reduce ischaemic complication risk unless contraindicated.

6. Pharmacology and AU PBS notes

Corticosteroids are the pharmacological backbone of this topic: oral prednisolone (40 to 60 mg daily, tapered over months) and IV methylprednisolone (500 mg to 1 g daily for three days) for GCA, and IV methylprednisolone (1 g daily for three days) for sight-threatening optic neuritis, each following well-established dosing conventions in Australian ophthalmology and rheumatology practice rather than a single national protocol document. Tocilizumab is PBS-listed for GCA as a steroid-sparing agent and is initiated by, or in consultation with, a rheumatologist. Intravitreal anti-VEGF agents (aflibercept, ranibizumab) are PBS-subsidised for macular oedema secondary to CRVO, administered by an ophthalmologist under strict aseptic technique; bevacizumab is used off-label where cost is a barrier. Aspirin is used both as secondary stroke prevention after amaurosis fugax or CRAO and as a low-dose adjunct in confirmed GCA. There is no PBS-listed pharmacological therapy that reverses established retinal infarction in CRAO or restores vision once a retinal detachment has occurred; both remain primarily surgical or supportive problems.

7. Complications and monitoring

CRAO usually leaves permanent, profound vision loss, since the therapeutic window is almost never met in practice; ocular neovascularisation and neovascular glaucoma can develop in the following weeks and require monitoring, and the shared vascular risk factors carry an ongoing risk of stroke and myocardial infarction that outlasts the eye event itself. CRVO risks chronic macular oedema with permanent central vision loss if undertreated, and neovascular glaucoma, particularly after the ischaemic subtype, within the first 100 days (about three months). Retinal detachment can be complicated by proliferative vitreoretinopathy, in which scar tissue formation causes redetachment, by permanent visual field or acuity deficit especially where the macula was off or surgery delayed, and by an elevated risk of detachment in the fellow eye where predisposing factors such as high myopia or lattice degeneration are bilateral. Vitreous haemorrhage can recur, and a missed retinal detachment underlying a dense haemorrhage is the key complication averted by routine B-scan ultrasound. Optic neuritis carries a risk of conversion to clinically definite MS that rises with MRI lesion burden, together with residual mild dyschromatopsia or contrast sensitivity impairment even after acuity itself recovers, and a risk of recurrence in either eye. Amaurosis fugax carries a stroke and myocardial infarction risk in the following days to weeks comparable to a cerebral TIA, which is the entire rationale for its urgent work-up. GCA is the highest-stakes diagnosis in this topic: untreated, involvement of the fellow eye typically follows within days of the first, producing irreversible bilateral blindness, and long-term complications include large-vessel involvement with aortic aneurysm or dissection, which warrants periodic surveillance imaging, alongside the cumulative steroid-related complications of osteoporosis, hyperglycaemia, and adrenal suppression that require bone protection and monitoring across the prolonged treatment course.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.