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 ²,³. This is particularly important if the person presents with rapid-onset visual loss or visual distortion (metamorphopsia) ²,³. Ideally, the patient should be seen within one week of referral ²,³.

• 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 ²,³.
• Colour fundus photography, used to provide a record of the retina's appearance ²,³.
• Optical coherence tomography (OCT), a non-invasive imaging technique that produces high-resolution cross-sectional and three-dimensional images of the retina ²,³. This test is considered mandatory for diagnosis and monitoring response to therapy in some retinal conditions ²,³.
• Fluorescein angiography (FFA), which involves an intravenous dye injection to detect abnormal vasculature or leakage from capillaries ²,³.
• Indocyanine green angiography (ICG), which may be used to visualise the choroidal circulation and provides additional information to FFA ²,³.

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).