Sickle cell and vision impairment

Sickle cell has many complications. Patients with sickle cell disease may have myriad medical complications from their hemoglobinopathy, including recurrent vaso-occlusive pain crises, strokes, silent cerebral infarcts, pulmonary hypertension, avascular necrosis of the bones and nephropathy. Dehydration, decreased oxygen levels, and infection can all cause sickling and a crisis.

I want to talk about total or partial vision loss or retinopathy, or vitreous haemorrhage and/or retinal detachment, in medical terms. Let’s start by reminding ourselves what sickle cell is. ‘Normal red blood cells are round but for people living with sickle cell, theirs is the shape of a sickle and hence the name. This means they do not have enough blood in their system. The main symptoms of sickle cell disorder are anaemia and episodes of severe pain. The pain occurs when the red blood cells stick together, causing blockages in the small blood vessels.’[1]

As a result of the above, people who have sickle cell disease can sometimes have vision problems. Blood vessels that lead to the eyes can get blocked or trapped by sickled cells, causing damage to the retina known as retinopathy, blocking the blood flow.

Sickle cell retinopathy is the most representative ophthalmologic complication of sickle cell disease, a hemoglobinopathy affecting both adults and children. SCR presents a wide spectrum of manifestations and may even lead to irreversible vision loss if not properly diagnosed and treated at the earliest. Patients with retinal involvement of sickle cell disease often do not have any eye symptoms. Sometimes, this can occur after a sickle cell crisis. Let’s learn more about it.

What is sickle cell retinopathy?

Retinopathy is damage to the retina in the eyes. Sickle red blood cells can get trapped inside the small blood vessels in the retina. The retina is the “seeing” part of the eye. The retina is a light-sensitive layer of cells at the back of the eye that processes incoming light and sends signals to the brain. It contains nerves and small blood vessels.

It captures light and images so that we can see. Eye problems caused by sickled blood cells can be found in all types of sickle cell disease. This may happen suddenly, without any warning.

There are two types of sickle cell retinopathy:

Non-proliferative sickle retinopathy (NPSR): Because the sickle-shaped red blood cells create blockages in the blood vessels, the retina suffers from a lack of blood flow and cannot receive important nutrients and oxygen. Initially, this occurs on the peripheral retina, causing initial findings known as salmon patches due to the leakage of blood from vessels. Over time, these leaks are resorbed, and the area appears normal with iridescent spots. Eventually, this leads to the development of black sunburst spots in response to the bleeding.

Proliferative sickle retinopathy (PSR): In PSR, long-term deprivation of oxygen and lack of blood flow causes the body to produce vascular growth hormone. This leads to the growth of blood vessels. Most of these newly formed blood vessels, however, are irregularly shaped, and instead of promoting blood flow, they cause further leakage of blood and increase the bleeding behind the retina. Eventually, this results in vitreous haemorrhage, blood in the jelly-like filling in the back part of the eye, or tractional retinal detachment, which causes vision loss.
Cause of retinal detachment?

Sickle cell retinopathy can be caused by a decrease in blood flow, leading to damage of the retina. The damage may be permanent. Another cause is bleeding in the eye. When blood vessels are blocked, the eye makes new vessels to replace the blocked vessels. The new vessels are thinner and weaker. They may break open and bleed. The bleeding causes damage to the retina. Bleeding can also cause the retina to become loose from the rest of the eye. This is called a detached retina. Damage to the retina can cause changes in eyesight. If the damage is not treated, blindness may occur.

What are the symptoms of sickle cell retinopathy?

At first, there may be no symptoms. This is why an eye doctor needs to check your eyes each year. The symptoms of retinopathy can include floaters (coloured spots that ‘float’ in your field of vision); blurred vision; vision blocked by patches or streaks; reduced night vision or sudden vision loss. In the worst cases, the retina may come loose, leading to permanent blindness.

Sickle cell retinopathy can affect several parts of the retina.

Proliferative sickle retinopathy: This occurs in ischemic retina. In response to the lack of oxygen, these tissues release factors that promote blood vessel formation that impacts vision. However, these blood vessels are fragile and can cause bleeding. These vessels can also form networks that resemble a sea fan and are characteristic of sickle cell retinopathy.

Sickle cell maculopathy: It affects the centre part of the retina and occurs when there is decreased blood flow to this part of the eye. This abnormal blood flow causes patches of retinal thinning. Patients will sometimes note blind spots as a result.

Vitreous haemorrhage, or bleeding in the centre part of the eye, can occur when abnormal retinal blood vessels break.

Retinal detachments: This can occur from tears in the ischemic retina, or from pulling of abnormal blood vessels and scar tissue on the retina. This can cause significant vision loss.

Retinopathy Treatment: Retinopathy can be treated by using laser surgery to repair damage to the blood vessels and retina. Or also by waiting months for the vision to come back to normal if it is not a total vision loss at the onset and that is why people living with sickle cell are advised to visit their ophthalmologist, at least once a year for eye examination.

Sources: www.choa.org; www.sicklecellsociety.org; www.nhs.co.uk; www.webmd.com and www.verywellhealth.com