OCT-A Scans for Wet AMD and RVO: Powerful Tool in Modern Retinal Diagnosis
Patients with blurred or distorted central vision often worry about wet age-related macular degeneration (wet AMD), particularly when changes occur suddenly. Accurate and timely diagnosis is essential because wet AMD can cause irreversible damage to central vision if treatment is delayed.
Mr Praveen Kumar, an experienced ophthalmology consultant serving patients in Reading, Windsor and across Berkshire, has 35 years of experience in ophthalmology, including 18 years specialising in medical retina and age-related macular degeneration (AMD). He is also a lead consultant for AMD at a local NHS hospital, with extensive experience in the assessment and management of complex retinal conditions.
One of the advanced imaging technologies used in modern retinal assessment is OCT-A (Optical Coherence Tomography Angiography). This powerful, non-invasive imaging technique provides valuable information about the blood vessels within and beneath the retina and can be particularly useful when assessing suspected or established wet AMD. Its applications, however, extend well beyond AMD and include retinal vein occlusions, diabetic retinopathy and diabetic macular oedema.
What is an OCT-A scan?
OCT-A is an advanced form of retinal imaging that can visualise the retinal and choroidal circulation without the need for an intravenous dye injection. It can help clinicians identify abnormal blood-vessel networks, areas of reduced blood flow and changes in the fine vascular architecture of the retina.
Unlike a standard OCT scan, which primarily provides detailed images of the structure, thickness and layers of the retina, OCT-A provides information about blood flow and vascular patterns. Using both structural OCT and OCT-A can therefore give the retinal specialist a more comprehensive picture of what is happening at the macula.
For patients, OCT-A is quick, painless and non-invasive, making it a valuable addition to a comprehensive retinal examination.
OCT scan and OCT A scan is often performed with machine on same sitting.
How can OCT-A help in diagnosing wet AMD?
Wet AMD occurs when abnormal blood vessels develop beneath or around the macula and can leak fluid or blood, potentially damaging central vision. OCT-A can help detect and map these abnormal vascular networks, sometimes revealing neovascularisation that may not be immediately obvious from structural imaging alone.
Importantly, OCT-A can also help the retinal specialist understand the type, location and pattern of neovascularisation. Differentiating between different forms of wet AMD can be clinically important because the appearance and behaviour of abnormal blood vessels may influence diagnosis, monitoring and treatment planning.
OCT-A and wet AMD mimics
Not every patient with fluid or abnormal-looking changes around the macula has conventional wet AMD. A number of retinal conditions can mimic neovascular AMD, and distinguishing these conditions can sometimes be challenging.
OCT-A may provide additional vascular information that helps separate wet AMD from some of its mimics. This can be particularly valuable in patients whose retinal findings are atypical, longstanding or difficult to interpret or getting eye injections wrongly.A correct diagnosis is important because different retinal diseases may require very different approaches to treatment and monitoring.
OCT-A in retinal vein occlusions
The usefulness of OCT-A extends beyond AMD. It can provide important information when assessing retinal vein occlusions (RVO), including branch retinal vein occlusion and central retinal vein occlusion.
A retinal vein occlusion can disrupt normal retinal blood flow and may result in retinal swelling, haemorrhage and, in some cases, macular ischaemia. OCT-A can help identify areas where the normal retinal capillary network has been disrupted or where there is reduced or absent blood flow.
Assessing the macular circulation can provide additional information about the extent of vascular damage and help the retinal specialist understand why visual function may be affected. OCT-A can therefore complement structural OCT, which is particularly useful for identifying and monitoring macular oedema associated with retinal vein occlusion.
OCT-A in diabetic retinopathy and diabetic macular oedema
OCT-A is also increasingly useful in the assessment of diabetic retinal disease.
Diabetes can damage the tiny blood vessels supplying the retina. OCT-A can demonstrate abnormalities in the retinal microvasculature, including changes to the capillary networks and areas of reduced or absent perfusion. This can provide valuable information when assessing the severity and distribution of diabetic retinal vascular disease.
In patients with diabetic macular oedema (DMO), conventional OCT remains particularly important because it provides detailed structural information about retinal thickening, fluid and other changes within the macula. OCT-A can complement this by providing information about the underlying retinal circulation and macular perfusion.
This combination of structural and vascular information can be especially helpful in complex cases, where the degree of retinal swelling and the health of the macular circulation may both contribute to visual impairment.
A powerful tool across medical retina
OCT-A has become an important addition to the retinal specialist's imaging toolkit. Its ability to provide detailed information about retinal and choroidal blood vessels makes it useful in a range of medical retinal conditions, including:
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Wet age-related macular degeneration (wet AMD) and choroidal neovascularisation
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Different patterns and types of macular neovascularisation
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Wet AMD mimics and atypical macular conditions
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Retinal vein occlusions, including assessment of macular ischaemia
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Diabetic retinopathy and retinal microvascular changes
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Diabetic macular oedema, alongside structural OCT
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Assessment of retinal and macular perfusion