What Is Retinal Haemorrhage?

Introduction 

Retinal haemorrhage is defined as bleeding within the retina caused by damaged blood vessels. Haemorrhage is a medical term used to describe a loss of blood from damaged blood vessels.¹ Retinal haemorrhages can vary in size, ranging from small dots to fully covering the retina which can lead to vision loss, and can also occur in different locations within the retina.² The extent of the damage caused by the retinal haemorrhage is dependent on the cause of the bleeding and the amount of blood lost.

Retinal haemorrhage is a common reason to visit the eye clinic.² Mild retinal haemorrhage is found in children under the age of two who have no history of trauma or abuse, although, up to 30% of retinal haemorrhage cases found in children are the result of physical abuse.² In adults, retinal haemorrhage is common in patients older than 40, or who suffer from systemic disorders.² 

Retinal haemorrhage can occur through trauma ( e.g. head injuries) or due to underlying medical conditions.² Therefore, a good understanding of the location, size, stage of bleeding, and distribution of bleeding can help to identify the condition a patient may have.² This can then be used to diagnose and treat the patient and manage the haemorrhage.

Anatomy of the retina 

The retina is a layer within the eye that is responsible for capturing light which is transferred into electrical signals allowing us to see.³ Within the retina there are two main types of cells:

1. Photoreceptor cells that include rods and cones
2. Glial cells 

Light enters the eye through the pupil and hits the photoreceptor cells of the retina. The cones and rods then transfer the light into electrical signals which travel from the optic nerve to the brain. In the brain, the light is then converted into images that allow us to see.⁴

Photoreceptors

Photoreceptor cells are light-sensitive cells that include rods and cones and are situated at the retina, and the back of the eye.⁴ Rod cells are more sensitive when there are low levels of light (i.e. at night) and are positioned towards the edges of the retina. In contrast, the cone cells are more suited for higher levels of light (i.e. during the day) and are situated at the centre of the retina.³ Within the retina, there are more than 100 million rods and 6 million cones which are required to detect and sense a wider range of wavelengths within light. 

Glial cells

Glial cells have numerous functions:⁵

• Provide support to the retina
• Direct neural signals
• Mediate transport of nutrients in the retina
• Removal of waste products

Blood supply to the retina

The major blood vessel responsible for supplying blood to the retina is the central retinal artery which is accompanied by branches of the short ciliary arteries.⁶ The central retinal artery travels alongside the optic nerve and then branches outwards to supply the inner layers of the membrane.⁶ The short ciliary arteries supply the choroid which is the vascular layer located between the retina and the sclera (white outer layer of the eye).⁷ The choroid is responsible for providing blood and nutrition to the outer layers of the retina.⁴ The central retinal vein takes the blood back to the heart to be oxygenated and removes the waste products away from the retina.⁴

The retinal blood vessels are responsible for providing blood to the retinal neurons.⁸ The nerve cells require a fresh supply of oxygen and nutrients to survive. The retina is also one of the most metabolically active tissues within the body and requires a large amount of oxygen and nutrients to function properly.⁸ Without the presence of intact, undamaged blood vessels, the cells within the retina will die, which could lead to vision loss.

Causes of retinal haemorrhage

Retinal haemorrhage is caused by damage to the blood vessels within the eye. The most common causes of retinal haemorrhage include trauma, vascular disease (diseases affecting blood pressure), and autoimmune diseases.⁴ 

Trauma

Retinal haemorrhage is dependent on the type of trauma, which may include:⁴

• Eye injuries: Any damage to your head or eyes can cause the blood vessels within the retina to become damaged
• Shaken baby syndrome: Bleeding within the brain and retina which occurs when a baby or toddler is violently shaken
• Altitude sickness: Sudden change in air pressure when moving to a higher elevation too quickly can cause damage to the blood vessels
• Head injuries: Head injuries caused by car accidents or child abuse can also cause retinal haemorrhage

Vascular disease

Medical conditions that affect the blood vessels can also cause retinal haemorrhages. These include:

• High blood pressure (hypertension) is when the blood pressure is higher than normal. Higher blood pressure causes damage to the blood vessels, which decreases the blood flow and can cause blockages
• High cholesterol is defined as too much cholesterol (fatty substance) in the blood as a result of a poor diet. This can cause a blockage within the blood vessels. Subsequently, the retinal blood vessels become damaged, which leads to bleeding within the retina
• Anaemia is a medical condition where your blood produces less amount of healthy red blood cells compared to healthy individuals.⁹ Anaemia can cause blood vessels to break and lead to bleeding in the retina. This may occur in either one or both eyes⁴
• Retinal vein occlusion is when there is a blockage in the retinal vein. This can cause bleeding within the retina

Autoimmune disease

Autoimmune disease is defined as an inability of the immune system to differentiate between foreign bodies and your own body, causing the immune cells to attack healthy cells.¹⁰ Some types of autoimmune diseases can also cause bleeding within the retina

• Diabetes is a condition that causes the blood sugar concentration to become uncontrollable. In type 1 diabetes, the immune system targets the pancreatic B-cells that are responsible for making insulin which is a hormone that controls blood sugar levels.¹¹ Too much sugar within the blood can cause damage to the blood vessels resulting in blockages within the retinal vessels. This can cause bleeding within the retina
• Lupus is an autoimmune disease which causes inflammation to occur throughout the body.¹² The blood vessels supplying the retina can become inflamed which restricts blood flow to the retina and can potentially lead to bleeding

Symptoms 

In some cases of retinal haemorrhage, there are no symptoms, and the bleeding can occur without any warning. However, as the retina is crucial for visualisation, even a small bleeding or injury can lead to blurred vision and result in blind spots.¹³

The most common symptoms include¹³ 

• A blurred vision 
• Blind spots 
• Spots or patches of darkness in your vision 
• Red vision
• Worsened vision in the morning 

Complications

1. Visual impairment: Visual loss caused by retinal haemorrhage is a symptom some patients suffer from and may point towards a diagnosis.⁴ Most retinal haemorrhages won’t lead to permanent visual impairment.⁴ However, larger haemorrhages might cause permanent visual impairment, including vision loss⁴ 
2. Retinal detachment: Retinal detachment is a serious medical condition where the retina becomes detached from the back of the eye which can cause vision loss and even blindness.¹⁷ Retinal haemorrhage increases the risk of developing retinal detachment through the leakage and swelling of retinal blood vessels.¹⁸ Although retinal detachment may be painless, it requires immediate medical treatment¹⁷ 
3. Macular oedema: Macular oedema is a condition that occurs when the blood vessels bleed into an area of the retina called the macula,¹⁹ causing it to swell, and leading to blurred vision. The most common type of macular oedema is diabetic retinopathy which is an eye condition that causes vision loss in those who are diabetic¹⁹

Diagnosis 

To diagnose retinal haemorrhage, a medical specialist is required to conduct an eye test. Diagnostic methods include:

1. Ophthalmoscopy
2. Optical coherence tomography
3. Fluorescein angiography
4. Blood test

Ophthalmoscopy

Ophthalmoscopy is a medical procedure where the back of the eye is examined using an ophthalmoscope.¹⁴ It is used to detect retinal detachment and eye disease and to determine what is causing the blood vessel damage.¹⁴ Ophthalmoscopy is an effective diagnostic tool, with a 90% to 95% accuracy. It can also detect early stages of many serious diseases, such as the signs of high blood pressure, diabetes and other types of vascular disease.¹⁴

Optical coherence tomography (OCT)

OCT is a non-invasive imaging test which uses light waves to take a cross-section of the retina.¹⁵ This allows doctors to visualise each layer of the retina and detect retinal disease. The OCT can also take pictures of the blood vessels supplying the retina to identify retinal haemorrhage and determine which blood vessels are damaged.¹⁵ However, as OCT is reliant on light entering the retina, significant bleeding within the retina may interfere with this process, in which case, OCT may not be the best choice, despite its ease and speed of use.¹⁵

Fluorescein angiography (FA) 

FA is an imaging test that allows doctors to view the blood vessels in the retina, using fluorescein as a dye to inject through a vein in your arm.¹⁶ This allows for the identification of which blood vessels are damaged and causing the retinal haemorrhage. 

Blood tests

Blood tests are done to help diagnose the underlying systemic problem that may be causing the retinal haemorrhage.⁴ These tests check for:

• Diabetes and blood sugar levels
• Cholesterol levels
• Signs of infections including antibodies and immune cells

Management and treatment

Treating retinal haemorrhage will depend on several different factors:

1. What caused the bleeding?
2. How severe is the bleeding?
3. Is your vision impaired?

If the haemorrhage is small, isn’t affecting your vision and is not getting worse, no treatment will be required. Most people will not need treatment as the haemorrhage can heal itself. However, if treatment is required, it will most likely be:

1. Laser photocoagulation
2. Anti-VEGF Injection
3. Treating the underlying causes 

Recovering from a retinal haemorrhage depends on the treatment given, specific symptoms and the causation of the haemorrhage. It usually takes a few weeks to repair a retinal haemorrhage.¹ Bed rest with an elevated head can help reduce bleeding⁵ and avoiding anticoagulant medicine will also speed up healing.

Laser photocoagulation

Laser photocoagulation is a minimally invasive eye surgery that uses lasers to seal broken blood vessels, preventing them from leaking blood into the retinal space. ²⁰ The lasers work by burning and destroying parts of the retina, which might come with risks:

• Mild central vision loss
• Reduced night vision
• Blurred vision after surgery
• Mild pain associated with the procedure

However, the risks of the procedure are outweighed by the severe vision loss that can occur without treatment. 

Anti-VEGF injection

Vascular endothelial growth factor (VEGF) is a growth factor that is responsible for forming blood vessels, whereas anti-VEGF is a medicine that is used to reduce blood vessel formation.²¹ Anti-VEGF is injected into the eye to slow the progression of damage in the blood vessels and therefore, slows down vision loss. Anti-VEGF is an effective treatment for treating retinal haemorrhage and improves vision in 1 in 3 people who take the medicine.²¹

Treating underlying conditions

Other medical conditions can cause retinal haemorrhage. By targeting and treating these diseases, we can then treat the retinal haemorrhage. For example, taking medicine to reduce blood pressure and cholesterol levels, and making lifestyle changes can reduce the pressure on the blood vessels and prevent haemorrhage. Controlling blood sugar is an effective treatment for a diabetic patient with retinal haemorrhage.

Prevention

To prevent retinal haemorrhage, it would be best to avoid the conditions that caused them. As retinal haemorrhage is caused by damage to blood vessels, preventing blood vessel damage is a key step to reducing the risk of retinal haemorrhage.

These include:

• Lifestyle modifications
• Regular eye exams
• Control of systemic conditions

Lifestyle modification

Changing your lifestyle by eating a healthier diet that is low in saturated fats, cholesterol, sodium and sugar can improve your blood vessel health. Exercising regularly and maintaining a healthy weight is also important as obesity can cause a burden on the blood vessels, making them more prone to damage.

Regular eye exams

Visiting the opticians is important in preventing retinal haemorrhage as they can detect the problems before any symptoms occur. It’s suggested that adults over the age of 55 years should visit the opticians every one to three years even if they have perfect vision.

Control of systemic conditions

Certain medical conditions can increase the risk of developing retinal haemorrhage. For example, diabetic patients or patients with high blood pressure are at higher risk. Controlling blood sugar and blood pressure can help prevent retinal haemorrhage.

Prognosis

Most patients with retinal haemorrhage make a full recovery. Infants and younger children with retinal haemorrhage also have a good prognosis and the bleeding can be healed in two to four weeks.⁴ For patients with high blood pressure or blood sugar, the prognosis for the retinal haemorrhage is improved when the underlying condition is treated.⁴ However, retinal haemorrhage without treatment does have a poor prognosis and can lead to visual impairment.

Vision impairment

There is a chance that the retinal haemorrhage causes permanent damage to your retina despite the treatment, which could lead to visual impairments. It is also possible to have poor or low vision for the rest of your life, which can include blurred vision or blind spots.

Summary

Retinal haemorrhage is caused by damage to the blood vessel that supplies the retina. Damage can be caused by trauma (injury to the head or eye) or by health conditions like diabetes or high blood pressure. Retinal haemorrhage usually occurs in one eye but can be present in both eyes at the same time.

Symptoms may vary depending on what caused the bleeding, with some patients having no symptoms or being unaware of having retinal haemorrhage. However, in other patients, they may lose their vision. Vision loss is uncommon but in some rare cases, patients can have permanent damage to the retina, which causes permanent vision loss.⁴

There are several treatments available to manage retinal haemorrhage and prevent vision loss but this will depend on the cause, amount and location of the bleeding.

If there are any changes in your vision, please visit the opticians as soon as possible. Some symptoms to watch out for include: 

• Blurry vision
• Patches of black spots
• Blind spots
• Vision loss

Overall, the prognosis for retinal haemorrhage is good, with several treatments available to prevent vision loss. Fortunately, in most cases, retinal haemorrhages are small leakages that will heal naturally and will not need medical intervention.