Acute blindness

A 67-year-old lady with a background of hypertension presents to ED complaining of unilateral vision loss. This started 3 days ago when she saw some flashing lights. Since then, there has been progressive visual loss and darkness spreading from the temporal aspect of her visual field towards the centre. She has no eye pain, headache or jaw ache.

Her pupils are equal and reactive but the vision in her right eye is dramatically reduced, and she can barely distinguish hand movements.

Immediate PoCUS exploration of the right eye reveals a thin hyperechoic membrane that appears to float at the rear end of the ocular globe. In the second clip, appreciate how this hyperechoic structure originates from the optic nerve.

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• What is the most likely diagnosis?

  This patient’s painless visual loss is concerning for a retinal detachment. This hypothesis is supported by the history of ‘flashing lights”, which represent damage to the photoreceptors. Temporal arteritis can cause transient or permanent monocular visual loss (without flashes) but is usually accompanied by features such as headache with scalp tenderness or jaw claudication. Acute angle closure glaucoma presents as painful monocular visual loss and is associated with anterior segment findings such as conjunctival hyperaemia, corneal clouding, and a shallow anterior chamber. Visual loss in a cerebrovascular accident is binocular, such as in the case of homonymous hemianopia.

• Based on the likely cause, what is the most appropriate immediate management plan?

  Alongside floaters, flashes are red flag symptoms and can point towards a sight-threatening pathology such as retinal detachments, retinal tears or vitreous haemorrhage. Any patient with new flashes or floaters needs an urgent and thorough assessment of their retina. This requires pupil dilation with mydriatic drops such as tropicamide 1%, unless contraindicated. However, bear in mind that direct fundoscopy is limited in its ability to assess the peripheries of the retina and may miss pathologies located here. As a result, any patient with suspected retinal pathology should be referred for ophthalmological assessment, where they will undergo further examination and management. The urgency of referral is described by NICE CKS (1):

  Arrange immediate referral to an ophthalmologist with retinal surgery expertise to be seen on the same day, if there are signs of sight-threatening disease, such as:

  • Visual field loss or changes in visual acuity.

  • Fundoscopic signs of retinal detachment or vitreous haemorrhage.

  Arrange urgent referral to a practitioner competent in the use of slit lamp examination and indirect ophthalmoscopy to be seen within 24 hours, if there is:

  • No visual field loss.

  • No change in visual acuity.

  • No fundoscopic sign of retinal detachment or vitreous haemorrhage.

  The management of retinal detachment varies based on the cause and the duration of symptoms but is often surgical. Postoperative visual acuity is variable and depends on factors including the size and location of the detachment and the timing since onset of symptoms (2).

• In which region of the retina would you be most likely to identify the cause of his symptoms?

  To recap, she describes a dark curtain extending from the extremes of her temporal vision and extending more centrally. This implies pathology in the nasal portion of the retina, which receives light from the temporal visual field. This will allow a more targeted examination and nicely highlights the importance of a good history when it comes to visual phenomena.

Key Learning Points:

• Flashes and floaters are red-flag symptoms that warrant immediate or urgent Ophthalmic assessment.

• PoCUS has a role in the ED to help diagnose retinal detachment

• Peripheral retinal pathology can be missed with direct fundoscopy.

• A careful history of visual phenomena is essential for honing down the likely cause and location of ocular pathology.

References:

(1)   NICE CKS. Retinal detachment. Available from: https://cks.nice.org.uk/topics/retinal-detachment/management/management-of-suspected-retinal-detachment/. 2019 [cited 26 Jan 2023]

(2)   Sultan ZN. Rhegmatogenous retinal detachment: a review of current practice in diagnosis and management. BMJ Open Ophthalmology 2020. DOI: 10.1136/bmjophth-2020-000474.

Literature review & Study questions by Harry Melville | Case & Images by Felipe Urriola