Sudden Visual Loss

Loss of vision can be a scary symptom for patients to experience, and a scary presentation for doctors to manage! You will not be expected to know the causes in detail. However, some knowledge of the following conditions will help you to risk-stratify patients. These patients will most likely require an urgent referral to your ophthalmology colleagues for advice or review.

General approach

It is helpful to split the causes of sudden visual loss into painful and painless.

The table below highlights some of the more common causes of sudden visual loss:

SuddenAnterior Uveitis
Optic neuritis
Giant cell arteritis
Acute angle-closure glaucoma
Migraine / retinal migraine
Central retinal artery obstruction
Central retinal vein obstruction
Retinal detachment
Vitreous detachment
Vitreous haemorrhage

History: A detailed history can help to distinguish between these causes. As well as ascertaining the degree and pattern of visual loss, it is always useful to ask about symptoms such as pain, red eye, flashes/floaters and photophobia. Many ophthalmological conditions are associated with systemic conditions, and so a thorough review of symptoms can be key.

Examination: You will not be expected to perform a comprehensive eye examination as that involves things like using a slit lamp to visualise the anterior and posterior chambers of the eye. However, examinations such as testing visual acuity and fundoscopy are easy to perform and give vital information to you when referring or speaking to the ophthalmology team. When performing fundoscopy, always try to dilate the eyes before; otherwise, it will be challenging to visualise the retina.

A more detailed guide to the eye history & exam can be found on our article titled ‘Eye History & Exam

Below is an overview of some of the more common causes of visual loss. This is by no means comprehensive but aims to highlight some key points to know for each condition.

Painful, sudden visual loss

Anterior uveitis
Anterior uveitis can also be referred to as ‘iritis’ and refers to inflammation of the iris and/or ciliary body.

• Patients will complain of acute onset pain and may also complain of photophobia, red eye, blurred vision and tearing.
• Anterior Uveitis has a number of systemic associations such as ankylosing spondylitis, reactive arthritis, inflammatory bowel disease, and other rheumatological and infectious conditions.

• The pupils can be small and irregular.
• A slit lamp exam may reveal a hypopyon (pus in the anterior chamber – seen as a pool of white fluid in the bottom of the iris – pictured above).

• Suspicion of anterior uveitis should prompt urgent (same-day) referral to an ophthalmologist.
• The ophthalmologist may consider treating with cycloplegics (eye drops to dilate the eye), steroid eye drops, as well as antibiotics or antivirals depending on whether a systemic infection is present.

Optic neuritis
Optic neuritis refers to inflammation of the optic disc. The most common cause in a young patient is demyelinating disease, and this is what you are most likely to be asked about in exams.

• Patients may typically present with reduced visual acuity, reduced colour vision (red desaturation – reduced sensitivity to the colour red) and pain on eye movement.

• A relative afferent pupillary defect (RAPD) may be present on examination – when light is shone from the non-affected eye into the affected eye, the patient’s pupils will appear to dilate due to a relatively reduced level of light going through the diseased optic disc.
• It is important to perform a full neurological examination as other focal neurological deficits may be found.

• If evidence of optic neuritis is present, the patient should be referred immediately to ophthalmology and/or neurology for further workup, including MRI brain imaging.
• Treatment may include high dose steroids, and most patients go on to recover their visual function.

Giant cell arteritis (GCA)

GCA is a medical emergency. All patients with suspected giant cell arteritis should be promptly referred to their local hospital for further investigations.

• Patients tend to be >50 years old and may present with headache, reduced or blurred vision and jaw claudication (pain in the jaw associated with chewing).
• GCA has a strong association with polymyalgia rheumatica, and so it is important to ask about features such as muscle ache and morning stiffness in proximal muscles.

• You may find a tender, palpable artery.
• Inflammatory markers (CRP and ESR) are usually raised, however, normal inflammatory markers do not exclude the disease.

• If you are suspecting GCA, the patient should be started on high dose steroids referred for review by a rheumatologist.
• If visual symptoms are present, the patients should also be seen urgently (same day) by an ophthalmologist.
• A temporal artery biopsy can help to confirm the diagnosis and typically shows ‘skip lesions’.

Acute angle-closure glaucoma (AACG)
Impaired aqueous outflow results in a rise of intraocular pressure causing damage to the optic nerve.

• As well as acute visual loss, it can present with a sudden onset headache, haloes around lights and photophobia.
• It is more common with hypermetropia and after pupil dilation (both due to having shallower anterior chambers impairing the outflow of aqueous).
• Dilating eye drops are sometimes known to cause AACG for this reason.

• You classically see a ‘mid-dilated’ fixed pupil and unilateral red eye. (pictured above)

• Patients with suspected AACG should be referred urgently (same day) to an ophthalmologist.
• Treatment includes lowering the intraocular pressure (IV dexamethasone), reducing aqueous production (with beta-blocker/alpha-agonist eye drops) and increasing aqueous outflow (pilocarpine eye drops).

Painless, sudden visual loss

Central retinal artery obstruction (CRAO)
The central retinal artery is a branch of the ophthalmic artery and supplies the inner ⅔rds of the retina.

• Sudden unilateral loss of vision due to an embolus originating from the carotid arteries or diseased heart valves occluding the central retinal artery.

• The classic fundoscopic appearances are a pale retina with a cherry red spot at the macula.
• A relative afferent pupillary defect (RAPD) may be seen.

• It should be treated in a similar fashion to a stroke, with the commencement of aspirin and immediate referral to a stroke unit.
• Conservative management also includes ocular massage and anterior chamber paracentesis – both of which encourage a clot to travel further downstream and reduce the area of ischaemia.

Central retinal vein occlusion (CRVO)
Central retinal vein occlusion is usually due to in-situ thrombosis rather than an embolus.

• It can present with painless, unilateral visual loss which may be less acute than that of arterial obstruction.
• Patients with cardiovascular risk factors (diabetes, hypertension, smoking etc.), inherited thrombophilia and glaucoma are at increased risk of developing CRVO.

• Fundoscopy findings include large retinal haemorrhages and cotton-wool spots.

• Aspirin.
• Treating raised intra-ocular pressure if present.
• Control of underlying cardiovascular risk factors.

Retinal detachment

• Retinal detachment can initially present with photopsia (flashes of light) and floaters, progressing to blurred vision and vision loss.
• A peripheral shadow may be seen if the peripheral retina detaches, and central vision will be altered if the macula is detached.
• Visual loss is often described as a ‘curtain’ coming across the vision.
• Myopes (those with short-sightedness) are at increased risk due to stretching of the retina.

• Slit examination to confirm diagnosis

• Once the diagnosis is confirmed by slit-lamp examination, these patients are usually referred for retinal surgery.
• The degree of visual recovery is variable and can depend on the location of the detachment – poorer outcomes are seen when the macula is involved.

Vitreous detachment
This is when the vitreous separates from the retina and collapses, often due to an underlying retinal tear.

• Patients may experience flashes of light (worse in dim light) and floaters (worse against a white background).
• A finding of vitreous detachment can indicate the progression of diabetic retinopathy.

• Slit examination to confirm diagnosis

• Treatment is usually conservative, however surgery can be performed if there is an underlying retinal tear.

Vitreous haemorrhage
The common causes of vitreous haemorrhage include proliferative diabetic retinopathy and ocular trauma.

It can also be associated with vitreous and retinal detachment.

• Patients may experience flashes and floaters, a sudden reduction in visual acuity and a visual field defect

• Carry out visual acuity assessment and fundoscopy

• Warrants same-day referral to ophthalmology
• Largely involves treatment of the underlying cause.
• If associated with a vitreous detachment and retinal tear, surgery may be indicated.

Useful links

Written by Dr Tajwar Nasir (FY3)
Reviewed by Byron Lu Morrell (ST2 Ophthalmology)
Edited by Mudassar Khan (Y3 Medical Student)

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