What is proliferative sickle cell retinopathy?
If there is a reduced blood supply to the retina, the ischaemic retina produces an increase in a protein called vascular endothelial growth factor (VEGF). This protein stimulates growth of new blood vessels in the outer edges of your retina (peripheral retina). The new blood vessels are weak and leaky and can cause further damage to your retina and vision. When new blood vessels grow, it is known as proliferative sickle cell retinopathy (PSR). The new blood vessels form fan-shaped networks (known as sea-fan) along the surface of the retina and back of the vitreous gel inside the eye. Movement between the two surfaces can cause the new blood vessels to leak, resulting in a bleed into the vitreous gel, known as vitreous haemorrhage.
The development of these networks can vary from very small sea-fans that resolve on their own, to large fast developing sea-fans that join up with other sea-fans and expand.
In about four out of 10 people with PSR, the new blood vessels block up and the sea-fan resolves on its own. In other cases, the sea-fans do not grow much bigger and do not bleed either.
Many people with PSR have no symptoms in the early stages. However, some people with PSR can have temporary or irreversible sight loss. This affects roughly 10-12 out of every 100 people with sickle cell disease over their lifetime.
PSR is more common in people with HbSC type of sickle cell disease than those with HbSS. Some large studies have estimated it affects almost five in 10 people with HbSC and about two in 10 people with HbSS.
PSR usually starts between the ages of 15 and 24 in males and 20 and 39 in females. However, it can start as early as 8 years old in those with HbSC and 13 years old in HbSS.
The following factors can increase the risk of PSR causing sight loss:
- Age – increasing age can increase the risk of sight loss due to PSR.
- Male gender – males are more likely to experience sight loss due to PSR than females.
- HbSC – people with HbSC type of sickle cell disease are more likely to experience sight loss from PSR than people who have other types.
People with PSR can have sight loss from the following complications:
- Retinal detachment
- Vitreous haemorrhage
- sickle cell maculopathy
- Retinal artery occlusion
- Epiretinal membrane
- Macular hole
