What causes RVO?

Introduction to RVO

The main cause of the blockage in RVO is atherosclerosis – a buildup of fatty deposits in your blood vessels.^1,2

The function of the retinal veins is to drain blood away from the eye and back to the heart. In the event of a blockage, the blood is unable to flow, which causes the vessel to swell, rupture, and leak fluid into the area around the retina, known as the macula.¹

4 boxes labelled 1 to 4 with arrows between them and each with an image of a blood vessel with arrows showing the flow of blood. The image in the first box has a small lump on the inner wall, with the caption “fats in the blood become stuck to the vessel walls.”, the second has a bigger lump and the caption “these fatty plaques are sticky and catch particles in the blood.”, the third has the arrow with a reversed direction when it reaches the lump and a swelling in the blood vessel at this site, with the caption “the plaque narrows the vessel and eventually blocks blood flow.”, and the last is the same but with arrows pointing away from the blood vessel and the caption “pressure builds up until fluid is forced out or the vessel ruptures.”.

Line diagram of the cross-section of an eye. The pupil is a gap in the front of the eye, the lens is an oval shaped section behind the pupil, the retina is the inner layer of the back of the eye, with a purple patch on it which is labelled the macula, and the optic nerve is a line leaving the back of the eye.

The buildup of fluid in the macula is called macular edema. ‘Edema’ or ‘Oedema’ are alternative spellings for the same term, meaning ‘swelling’. Macular edema can result from macular conditions other than RVO, including wet age-related macular degeneration (wet AMD) and diabetic macular edema (DME). No matter the cause, this fluid interferes with light entering the eye and results in the loss of vision.

In response to these changes, a protein called vascular endothelial growth factor (VEGF) is produced more. This protein helps blood vessels to grow, but also increases their permeability, meaning they become more leaky.

So, why are some people more likely to experience RVO than others? The risk factors for RVO are related to the raised risk of fatty deposits forming.^1-3

5 circles with line drawings and captions. The first contains the text “ 60+” and is captioned “age”, the second contains a blood pressure band and the caption “high cholesterol and blood pressure”, the third contains a cigarette and the caption “a history of smoking”, the fourth has a weighing scale and “obesity”, and the last has a blood drop with sugar and the caption “diabetes”.

References

NHS Foundation Trust. Retinal vein occlusion. Available at: https://www.yorkhospitals.nhs.uk/seecmsfile/?id=2333. Last accessed April 2025.
Macular Society. Retinal vein occlusion (RVO). Available at: https://www.macularsociety.org/macular-disease/macular-conditions/retinal-vein-occlusion/. Last accessed April 2025.
Royal College of Ophthalmologists. RVO Guideline Executive Summary 2022. Available at: https://www.rcophth.ac.uk/wp-content/uploads/2015/07/Retinal-Vein-Occlusion-Guidelines-Executive-Summary-2022.pdf. Last accessed April 2025.