What initial investigations should be performed in a patient suspected of having retinal vein occlusion?

If a retinal vein occlusion (RVO) is suspected, the initial and crucial step in general practice is to arrange an urgent referral for ophthalmology assessment and investigations NICE CKS,NICE CKS. This is particularly important if the person presents with rapid-onset visual loss or visual distortion (metamorphopsia) NICE CKS,NICE CKS. Ideally, the patient should be seen within one week of referral NICE CKS,NICE CKS.

• Upon specialist assessment, investigations typically performed in a hospital eye service or fast-track retina clinic include:
• Slit-lamp biomicroscopy, which helps identify changes affecting the macula, such as haemorrhagic or exudative changes, and can detect retinal thickening NICE CKS,NICE CKS.
• Colour fundus photography, used to provide a record of the retina's appearance NICE CKS,NICE CKS.
• Optical coherence tomography (OCT), a non-invasive imaging technique that produces high-resolution cross-sectional and three-dimensional images of the retina NICE CKS,NICE CKS. This test is considered mandatory for diagnosis and monitoring response to therapy in some retinal conditions NICE CKS,NICE CKS.
• Fluorescein angiography (FFA), which involves an intravenous dye injection to detect abnormal vasculature or leakage from capillaries NICE CKS,NICE CKS.
• Indocyanine green angiography (ICG), which may be used to visualise the choroidal circulation and provides additional information to FFA NICE CKS,NICE CKS.

It is noted in literature that retinal vascular occlusions have been reviewed in the context of COVID-19 infection and vaccination Yeo et al. 2023.