What Is Sickle Cell Retinopathy?

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Sickle cell retinopathy is a complication of sickle cell disease, a group of blood disorders that cause red blood cells to become misshapen and break down. It occurs when sickle cell disease causes blockage of the blood vessels in the retina, a layer of tissue that senses light and sends images to your brain, and choroid, a thin layer of tissue that is part of the middle layer of the wall of the eye.

When these vessels are blocked, abnormal blood vessel growth can occur and the retina thins. Over time, vision becomes impaired.

Treatment of Proliferative Sickle Retinopathy

Verywell / Theresa Chiechi

Types of Sickle Cell Retinopathy

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 cause 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 hemorrhage, blood in the jelly-like filling in the back part of the eye, or tractional retinal detachment, which causes vision loss.

There are five stages of PSR:

  • Stage 1: Peripheral arterial occlusions, the obstruction of blood flow from the heart to the legs due to narrowing or blockage of the vessels, occur.
  • Stage 2: To allow blood flow around the peripheral arterial occlusions, the body attempts to create alternate pathways for blood flow. These alternate pathways, called arteriovenous anastomoses, allow for aberrant blood flow and create bigger areas of non-perfusion, where blood cannot be delivered to retinal tissue.
  • Stage 3: Areas of non-perfusion create larger areas with a lack of blood flow and oxygen flow, creating a sea fan appearance that is visualized using fluorescein angiography. This medical procedure uses a special dye and camera to look at blood flow in the retina and choroid.
  • Stage 4: Vitreous hemorrhage occurs.
  • Stage 5: Tractional retinal detachment occurs.

Recap

There are two types of sickle cell retinopathy: non-proliferative sickle retinopathy (NPSR) and proliferative sickle retinopathy (PSR). PSR has five stages, and stage 5 can result in significant vision loss.

Causes

People affected by sickle cell disease undergo a chemical change in their hemoglobin, which is a protein that carries oxygen and attaches to red blood cells. This change makes the hemoglobin become stiff rods, which then alters the shape of the red blood cells. Normally, red blood cells are round and can move easily throughout the body’s vessels. 

In a person affected by sickle cell disease, the stiff hemoglobin rods contort the red blood cell shape from a round to a crescent or sickle shape. As a result, these red blood cells cannot easily pass through the body’s vessels and can become stuck, creating blockages.

Recap

Sickle cell retinopathy only affects people with sickle cell disease. In sickle cell disease, red blood cells are shaped like a sickle, and can block blood vessels. This can damage various parts of your body, including your eyes.

Diagnosis

A diagnosis of sickle cell retinopathy is usually made by an optometrist or ophthalmologist. Findings that can lead to a diagnosis of sickle cell retinopathy include:

  • The presence of comma-shaped blood vessels in the sclera, or the white part of the eye, is common in sickle cell retinopathy. The sclera will also show signs of inflammation, which is known as bulbar conjunctiva.
  • Some people may have narrow, irregular lines deep in the retina, which are configured in a circular pattern around the optic disc. These are called angioid streaks.
  • Fluorescein angiography, to examine blood flow in retina and choroid, may reveal vessel blockages from the sickle cells.
  • Spectral domain optical coherence tomography is a test that shows cross sections of the retina and can detect thinning of the retina in sickle cell retinopathy.
  • Optical coherence tomography angiography is a type of imaging used to visualize blood vessels in the retina. It shows changes in the retinal and choroidal vessels, and is useful for detecting blocked vessels as a result of sickle cell disease.

Recap

Diagnosis of sickle cell retinopathy is made by an optometrist or ophthalmologist. They will use several diagnostic procedures to view the retina and choroid to look for damage from blockage and lack of oxygen.

Treatment

The goal of treatment is to identify sickle cell retinopathy early and preserve vision. Even with extensive retinal thinning, it's possible to maintain visual acuity.

For people with NPSR, there is no treatment. For PSR, there are a few therapies available:

  • Laser: For large areas of blocked blood vessels, a laser can reduce the size of the blockage and prevent the release of the vascular growth hormone and therefore creation of new but abnormal blood vessels.
  • Anti-vascular endothelial growth factor (Anti-VEGF): This medication is injected using a very thin needle into the eye. It blocks the release of the vascular growth hormone and prevents the body from creating new but abnormally shaped blood vessels.
  • Surgery: This may be needed to treat vitreous hemorrhage. It is also needed for retinal detachment to reattach the retina and prevent vision loss.

Recap

There is no cure for sickle cell retinopathy. Treatment is focused on preventing loss of visual acuity and blindness.

Prognosis

NPSR, especially when diagnosed early by an eye specialist, does not tend to cause loss of vision. Individuals who have NPSR may notice black spots or floaters in peripheral vision, but otherwise can maintain visual acuity.

PSR can have a significant impact on visual acuity and can even lead to total vision loss. Current recommendations are to have anyone diagnosed with sickle cell disease aged 10 and older be evaluated by an eye specialist at least annually so PSR can be detected in the early stages. Once PSR progresses to stage 4 or 5, the damage to the retina is significant and prevention of vision loss is more challenging.

Recap

Sickle cell retinopathy can cause loss of vision. Regular eye exams and early identification and treatment by an eye specialist are the best ways to prevent vision loss caused by sickle cell retinopathy.

Summary

Sickle cell retinopathy is one of the potential complications of sickle cell disease. It occurs when sickle cell disease causes blockage of the blood vessels in the retina and choroid, both of which are important to visual processing. When these vessels are blocked, abnormal blood vessel growth can occur and cause the retina to thin and become detached. 

A Word From Verywell

Sickle cell disease affects many parts of the body. One of them is the eyes. When it does, it's called sickle cell retinopathy. Left untreated, it can lead to vision loss. Understanding the sickle cell disease process and establishing routine care with an eye specialist can help you identify sickle cell retinopathy early and minimize visual loss with early treatment.

Frequently Asked Questions

  • Can anyone be affected with sickle cell retinopathy?

    People who have sickle cell disease are affected by sickle cell retinopathy. Sickle cell disease is an inherited disease. It is possible to have sickle cell trait, which means someone has one normal gene and one gene that is the inherited sickle cell gene. However, having it does cause sickle cell disease. You need both genes to be the inherited sickle cell gene. It is estimated there are one to three million people in the United States with the sickle cell gene, but only about 100,000 people develop sickle cell disease.

  • Will sickle cell retinopathy cause blindness?

    It can. If someone is diagnosed with proliferative sickle retinopathy, or PSR, and advances to stage 4 or 5, your vision can be negatively impacted. Furthermore, damage to the retina is extensive enough in these stages that it is possible for someone to have total vision loss from vitreous hemorrhage or tractional retinal detachment.

  • What can be done to treat sickle cell retinopathy?

    Management of sickle cell disease is a large part of treating sickle cell retinopathy. Decreasing the amount of sickle cells in the body can prevent sickle cell disease complications. Appropriate management of sickle cell disease can include medications (such as crizanlizumab or voxelotor), bone marrow transplants, and CRISPR gene therapy, which is used for targeted gene editing. Other interventions can include lasers, anti-vascular endothelial growth factor injections, and surgery for stages 4 or 5 PSR.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Ophthalmology. Sickle cell retinopathy. Updated April 24, 2021

  2. Review of Ophthalmology. Management challenges in sickle cell retinopathy. Published January 15, 2021.

  3. American Society of Retina Specialists. Sickle cell retinopathy. Updated 2020.

  4. Cleveland Clinic.  Sickle cell disease.  Updated February 25, 2020