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Key Points

• Flicker light provocation is a research technique measuring retinal vessel dilation upon exposure to pulsed light and is helpful in assessing vascular diseases such as heart disease, diabetes, hypertension and arteriosclerosis.
  
• Retinal vessel oximetry (RVO) is a technique of imaging the retina using two wavelengths of filtered light (one red and one green), one sensitive to haemoglobin and one not. Vessels with deoxygenated blood (veins) will appear darker than those with oxygenated blood (arteries). The ratio between the reflected red/green light from a vessel and that from surrounding tissues allows the calculation of an optical density ratio.
  
• RVO can detect increased venous oxygenation in diabetes and helps in monitoring the impact of the disease.
  
• RVO detects increased venous oxygenation in glaucoma which is found to correlate with visual field loss.
  
• OCT angiography shows promise in the assessment of diseases such as age related macular degeneration and diabetes and allows non-invasive visualisation of neovascularisation.
  
• Methods for screening the retina for early detection of Alzheimer's disease are unproven.