Retinal ischemia rarely appears by itself but is most often a complication of another disorder. This complication, called ischemia, cuts off blood and therefore nutrients to the retina. This leads to destruction or impairment of the cells in the retina.
How the condition affects a person’s vision depends on whether the affected blood vessels are in the center of the retina or to the side, or periphery. If the condition affects the center of the retina, vision loss can be considerable. Retinal ischemia that strikes the peripheral blood vessels may cause little loss of vision. This article will discuss what retinal ischemia is, its causes, symptoms and treatment.
What Is Retinal Ischemia?
In retinal ischemia something causes the central vein in the retina to separate from the eye. This is what causes the loss of oxygen and nutrients to the retina. This stimulates the body to produce a substance called vascular endothelial growth factor, which results in smaller blood vessels that compensate for the damaged central vein. However, these vessels are weak, tend to bleed and may cover the retina itself. This results in blindness.
Not only this, but a person who has retinal ischemia is at greater risk for having a stroke of their central nervous system. Retinal ischemia is basically a stroke that affects the eye.
Symptoms of Retinal Ischemia
- One symptom of retinal ischemia is a diminution of vision. There are patients that lose at least some of their vision suddenly but painlessly and permanently. For some people their vision becomes suddenly blurry, and in others their field of vision narrows to a small island surrounded by a haze or blackness. Other people experience a phenomenon like a shade being lowered over their visual field.
These disturbances are temporary and last from seconds to minutes. Sometimes they occur when the person changes their position, after they’ve eaten or if they’ve been exposed to bright light. Other people see flashes of bright light that are like the visual disturbances that accompany a migraine aura. Even if one eye is affected, the patient experiences these phenomena with both eyes.
- About 40 percent of patients with retinal ischemia feel pain. The pain is felt as a dull ache in or around the area of the eye and can last from hours to days. It is worse when the patient is sitting or standing up and is lessened somewhat when they lie down.
Causes of Retinal Ischemia
The causes of this condition can be a disease of the eye such as open angle glaucoma. This is the stealthy, painless and gradual type of glaucoma that can lead to blindness if it’s not treated. Other causes include:
- Diseases of the topic nerve.
- Occlusion, or blockage in the arteries that serve the retina.
- Malformations of the blood vessels the eye that lead to changes in the walls of the blood vessels.
- Diseases that have eye damage as a complication. These diseases can include diabetic retinopathy. This is a common complication of uncontrolled diabetes. Proliferative retinopathy is the more severe form and can lead to blindness. It causes tiny blood vessels to grow in the fluid filled part often eye called the vitreous humor. These vessels are weak, like the blood vessels produced by vascular endothelial growth factor, and they often rupture, bleed and cause the retina to swell.
Other uveitides, or conditions that affect the eyes include:
- AMPPE, or acute multifocal placoid pigment epitheliopathy, which is an inflammatory disease that affects the back of the eye. It usually improves on its own but can cause some vision loss and scarring of the retina.
- Myasthenia gravis, which is an autoimmune disease that attacks the muscles and can cause drooping eyelids and visual disturbances.
- Sarcoidosis, which is an inflammatory disease that can attack the eyes. Severe forms of the disease can cause inflammation of the optic nerve.
- Lyme disease, which is transmitted by a tick, can also affect the eyes by causing inflammation of the retinal blood vessels, the iris and other structures of the eye. The optic disc can also swell, which can result in vision loss.
- Cicatricial pemphigoid, which is a chronic disease that affects the conjunctiva, the membrane over the white of the eye. It can lead to scar tissue on the conjunctiva and adhesions between the eyelid and the surface of the eye.
- Trauma to the eye. The person can suffer a blow to the eye or something else that causes the pressure inside the eye to spike. This can compress or even tear the retinal vein.
Retinal Ischemia Treatment
Treating retinal ischemia depends on what is causing it. Because of this, there are many ways to treat retinal ischemia, though the success of these treatments is uncertain:
- One of the most popular types of treatment is PRP, or panretinal photocoagulation. It is also used to treat glaucoma. During this procedure, the surgeon uses the laser to burn away part of the outer edges of the retina. This stops the body from producing vascular endothelial growth factor and therefore stops the production of abnormal blood vessels. More effective drugs to halt the production of vascular endothelial growth factor are being studied.
- Other doctors prescribe steroids if the condition is being caused by neuropathy, but this doesn’t help the patient recover the vision that they’ve lost.
- Another way to treat neuropathy that has affected the optic nerve is to decompress it surgically, though this is not popular.
Since it is hard to find treatments that will fully restore the patient’s vision, they can be helped by rehabilitating their low vision. Ophthalmologists help by prescribing tools that control glare, magnifiers and special eyeglasses.
About 40 percent of patients who are treated for their retinal ischemia enjoy improved vision, while about 20 to 25 percent of people who have the condition in one eye will eventually develop it in the other eye.
The Bottom Line
Retinal ischemia remains a worrisome problem, but medical experts continue to explore ways in which it can be successfully treated. People who are at risk for the condition need to keep risk factors such as diabetes and high blood pressure under control.