13th February 2025

Acute vision loss

Overview of acute vision loss

The cause of acute vision loss can be categorised into ophthalmological, inflammatory (most notably uveitis), vascular, neurovascular and oncological. Migraine should be considered as a differential diagnosis for acute, transient vision loss, but with caution in those with no prior history of aura.

Ophthalmological

Cornea

Corneal disease is the most common ophthalmological cause for acute vision loss. It often presents as a flare of an underlying corneal disease. These include:

• Keratoconus
• Dry eye
• Corneal ulcer
• Corneal hydrops (a complication of corneal disorders causing corneal swelling)

Glaucoma

Acute angle closure glaucoma can present with acute vision loss alongside other symptoms and signs.

Optic nerve

Disorders affecting the optic nerve include:

Optic neuritis

This inflammation of the optic nerve. It results in unilateral, painful vision loss over hours or days. Examination will likely reveal reduced visual acuity, visual field loss, red desaturation (dyschromatopsia), painful eye movements and a relative afferent pupillary defect.

Investigations should include MRI as it has a high sensitivity and specificity for detecting inflammatory changes in the optic nerve. Management is with high-dose corticosteroids to accelerate the speed of visual recovery.

Optic neuritis is the initial presentation of multiple sclerosis in 25% of cases, and of those with multiple sclerosis, 70% will be affected by optic neuritis.

Papilloedema

This is optic nerve swelling due to raised intracranial pressure (ICP). Therefore, papilloedema is always bilateral but not necessarily symmetrical. Symptoms include nausea or vomiting and headaches which are worse when leaning forward. Possible underlying conditions include an intracerebral mass or haemorrhage, hydrocephalus, meningitis or idiopathic intracranial hypertension (IIH). Management relies on correcting the underlying cause to prevent optic nerve damage and irreversible vision loss.

Leber’s hereditary optic neuropathy

An inherited mitochondrial disease which predominantly affects young males. Symptoms typically begin at age 10-30 years with unilateral progressive optic neuropathy. The contralateral eye also becomes affected months to years later. Diagnosis is confirmed with genetic testing.

Infectious optic neuropathy

This is uncommon but can be caused by tuberculosis, hepatitis B, syphilis and cytomegalovirus.

Drug-induced optic neuropathy

1. Alcohol – chronic use can lead to vitamin B12 and folate deficiency.
2. Ethambutol – effects are irreversible and dependent on dose and duration. Patients taking ethambutol who are asymptomatic should have regular eye screening to monitor for optic nerve compromise. 
3. Amiodarone – causes optic neuropathy through nerve demyelination. Visual field defects are variable and nerve damage is not dose related. 
4. Vigabatrin – visual field defects can be bilateral and concentric and are predominantly nasal.

Retina

Retinal detachment presents with the 4 ‘Fs’: floaters, flashes, visual field loss and fall in acuity. Risk factors for detachment include high myopia (short sightedness) and recent trauma or surgery. 

Patients require urgent referral for surgery, which can include vitrectomy and gas or oil tamponade.

Vascular

Retinal vein occlusion and retinal artery occlusion

Retinal vein occlusion is more common than retinal artery occlusion and less sudden. Both need to be managed as an emergency. Note that branch retinal vein or artery occlusions can occur and typically present with vision loss to a lesser extent, and the patient may not even be aware of the defect.

Table 1 Clinical features and management of CRVO and CRAO

Image Source: Wikimedia Commons (2019). Fondo de ojo Ostrucción Vena central, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Fondo_de_ojo_Ostrucción_Vena_central.png (Accessed: 18 January 2024).

Image Source: Wikimedia Commons (2014). Cherry Red Spot Fiess, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Cherry_Red_Spot_Fiess.jpg, via Wikimedia Commons svg (Accessed: 18 January 2024).

Retinal vein occlusions can be clinically characterised into two types: ischaemic (25%) and non-ischaemic (75%) according to the area of non-perfusion in the posterior pole. Ischaemic retinal vein occlusions present with more severe vision loss, relative afferent pupillary defect and more marked fundoscopy findings. Prognosis is poorer and secondary complications are more common in ischaemic presentations.

Amaurosis fugax

Amaurosis fugax describes transient, painless monocular loss of vision caused by a carotid artery atheroma or embolus into the central retinal artery. It is considered as a retinal transient ischaemic attack (TIA) and hence the precursor to a stroke. Management should address any underlying cardiac risk factors and consider a carotid endarterectomy.

Vitreous haemorrhage

Vitreous haemorrhage can occur secondary to neovascularisation, retinal tears, retinal detachment or trauma. Neovascularisation is particularly significant in patients with diabetes because they can develop new retinal blood vessels (proliferative diabetic retinopathy) which are fragile and bleed easily. It is important the underlying cause is identified, and this may require an ultrasound if the blood obstructs the fundoscopy. Management may involve observation or a vitrectomy.

Anterior ischaemic optic neuropathy

Anterior ischaemic optic neuropathy (AION) is the most common cause of optic neuropathy in older people. It results from inflammation (arteritic) or atheroma (non-arteritic) causing blockage to the vascular supply of the optic nerve.

Arteritic AION is most commonly caused by giant cell (temporal) arteritis (GCA). GCA is classified as a medium-to-large-vessel vasculitis. Symptoms include monocular vision loss possibly preceded by episodes of amaurosis fugax, diplopia, new headache, jaw claudication and scalp tenderness. Examination reveals reduced visual acuity, optic disc oedema and thickened temporal arteries, which may be pulseless. Diagnosis can be confirmed with a raised ESR, raised CRP and a positive temporal artery biopsy. Note that due to skip lesions the biopsy may be falsely negative. Management with high-dose steroids should be started without delay (i.e. a positive biopsy result should not be awaited) to prevent vision loss in the other eye.

Other rarer causes of arteritic AION include other types of vasculitis, such as polyarteritis nodosa or systemic lupus erythematosus.

Non-arteritic AION is more common. It is typically painless and noticed on waking. Risk factors include hypertension, hypercholesterolaemia, diabetes mellitus and smoking. Management is to control these risk factors to prevent occurrence in the other eye.

Neurovascular

Haemorrhagic or ischaemic stroke can present with a visual defect. This can be a homonymous hemianopia, but the exact visual field loss is determined by the site affected.

Figure 3 recaps the visual field pathway and the resulting visual field defects according to which area is involved.

Image Source: Wikimedia Commons (2020). Hemianopsia en, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Hemianopsia_en.jpg, via Wikimedia Commons (Accessed: 18 January 2024).

Oncological

Tumours are rare as a cause of vision loss but can result in severe and progressive visual field defects. The exact defect is according to the site of the lesion, but typical examples include:

• Cerebral tumours: contralateral homonymous hemianopia
• Pituitary tumours: bitemporal hemianopia. These tumours can be non functional or produce hormones, e.g. prolactin, ACTH or growth hormone. Be aware of idiosyncratic presentations, such as skin hyperpigmentation seen in ACTH-producing tumours due to its effect on melanocyte-stimulating hormone receptors.

References

• BMJ Best Practice. Assessment of vision loss [Internet]. BMJ Publishing Group. 2023 [cited July 22 2023]. Available from: https://bestpractice.bmj.com/topics/en-gb/960
• Baldwin A, Hjelde N, Goumalatsou C, Myers G. Oxford Handbook of Clinical Specialties. 10 edn. Oxford Medical Handbooks, UK: Oxford; 2016
• Rigi M, Almarzouqi SJ, Morgan ML, Lee AG. Papilledema: epidemiology, etiology, and clinical management. Eye Brain. 2015 Aug 17;7:47-57. doi: 10.2147/EB.S69174. PMID: 28539794; PMCID: PMC5398730
• Bennett JL. Optic neuritis. Continuum (Minneapolis, Minn.). 2019 Oct;25(5):1236
• Hayreh SS. Management of ischemic optic neuropathies. Indian J Ophthalmol. 2011 Mar-Apr;59(2):123-36. doi: 10.4103/0301-4738.77024. PMID: 21350282; PMCID: PMC3116541
• Tadi P, Najem K, Margolin E. Amaurosis Fugax. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470528/
• Lim J et al. Retinal Artery Occlusion, EyeWiki. [Internet]. July 2023 [cited July 23 2023]. Available from: https://eyewiki.aao.org/Retinal_Artery_Occlusion