
What is epiretinal membrane?
Epiretinal membrane is a disorder of the interface area between the posterior vitreous and the central area of the retina, the macula.
An epiretinal membrane is a thin sheet of fibrous tissue that can develop on the surface of the macular area of the retina and can cause visual impairment. The retina is a clear film, a very delicate tissue that covers the inside of the eye fundus. The macula is located in the center of the retina and gives us sharp central vision and good near vision.
An epiretinal membrane develops as a result of cellular changes that occur in the back of the eye between the normally present clear vitreous gel and the macula. Normal biological cells derived from the retina and other tissues in the eye are released into the vitreous gel and eventually settle on the surface of the macula. These cells may begin to proliferate into a “membrane”. In many cases, this membrane remains very light and has no significant effect on the macula or the person’s vision. However, in other cases, the membrane may slowly become more prominent, eventually creating a retinal impairment that leads to visual blurring and/or distortion in the affected eye.
In most cases, an epiretinal membrane develops in an eye with no history of previous problems. This type of epiretinal membrane is called idiopathic. However, occasionally an epiretinal membrane will develop in an eye as a result of retinal detachment, trauma, inflammatory disease, blood vessel abnormalities or other pathological disorders. Most epiretinal membranes are mild and have little or no effect on vision. However, in some cases, the epiretinal membrane may grow slowly and cause mechanical distortions (“wrinkles”) in the macula. This can lead to blurred or distorted vision, which can slowly worsen over time. An epiretinal membrane does not cause an eye to become completely blind. It usually only affects the central area of vision and does not cause loss of peripheral (side) vision.
What are the symptoms of epiretinal membrane?
Epiretinal membrane is severe when it affects the central part of the retina responsible for seeing fine details. In the most severe cases, vision is blurred and distorted, similar to a distorted view through an unadjusted pair of binoculars. Straight lines, such as on a doorway, may appear wavy to someone with epiretinal membrane. Loss of vision begins unnoticeable and becomes increasingly severe.
A person should report any of the following symptoms to the ophthalmologist:
- Decreased vision or loss of central vision. Central vision allows the eyes to see in front for reading or driving or to see fine details.
- Distorted or blurred vision.
- Double vision.
- Wavy vision.
- Problems reading small letters
- In its advanced form, this membrane can cause complete destruction of cells in the central area, leading to what is called a “macular hole” with complete loss of vision
What are the risk factors for epiretinal membrane?
The occurrence of epiretinal membrane is idiopathic, i.e. its existence cannot be explained in relation to any other disease the patient may suffer from. In this case, the disorder occurs in healthy patients, without the presence of any other eye disease.
Most of the time, the sudden appearance of the epimacular membrane is caused by natural changes that occur in the vitreous body (part of the eye formed by a transparent gel situated in the center of the eye). These changes cause cells from the retina and other parts of the eye to enter the vitreous body. These cells eventually settle on the macula, where they can form a membrane.
A person’s risk of developing epiretinal membrane increases with age, and people with an existing eye or vision disorder may develop this disorder before the age of 50.
Eye disorders that put a person at risk of developing an epiretinal membrane are:
- Posterior vitreous detachment: separation of the gel that fills the back of the eye towards the retina.
- Retinal detachment: occurs when the retina is pulled away from the back of the eye.
- Injuries: Eye injury or trauma can cause epiretinal membrane.
- Surgery: eye surgeries, such as cataract surgery, can cause epiretinal membrane.
- Retinal vascular disease: disorders affecting the blood vessels in the eye, such as diabetic retinopathy. Diabetic retinopathy can affect people with diabetes.
- Existing epiretinal membrane: Having an epiretinal membrane in one eye means a greater likelihood of developing it also in the other eye.
- Having risk factors for epiretinal membrane does not guarantee that someone will develop the disorder in one or both eyes. Also, even someone who has no risk factors could develop epiretinal membrane.
In other cases, however, the epiretinal membrane may have a secondary cause, i.e. it may be the result of a previous eye problem. These include:
- Complication of retinal detachment surgery
- Eye inflammation
- Retinal blood vessel abnormalities
- Eye trauma
- Intraocular tumors
- Degenerative retinal disorders
How can epiretinal membrane be prevented?
There are no concrete measures to prevent the development of an epiretinal membrane. But, it is important to consult an ophthalmologist if you suspect symptoms (such as floating particles or flashes).
What types of epiretinal membranes are there?
Diagnosis and classification of epiretinal membrane were based on the results of clinical examinations. In clinical practice they are frequently classified as either macular reflex, the early form, or preretinal macular fibrosis, the late form.
Slit-lamp biomicroscopy of the macular reflex reveals a bright, watered silk luminous reflex from the inner surface of the retina. In some cases, preretinal macular fibrosis develops as the membrane thickens and contracts, with the superficial retinal folds, or traction lines, becoming opaque and grey. Preretinal macular fibrosis can distort the retina, resulting in visual impairment in ~80% of cases. Severe cases may involve retinal hemorrhages, exudates, vascular abnormalities, edema, macular pseudo holes and macular holes, resulting in other visual impairments.
In addition to clinical examination, a variety of ancillary tests can help diagnose and classify epiretinal membrane; for example, angiofluorography can help diagnose retinal edema.
What treatment methods exist for epiretinal membrane?
Epiretinal membranes can be treated by surgery – vitrectomy. However, not all epiretinal membranes require treatment. Surgery is not necessary if the epiretinal membrane is mild and has little or no effect on vision. There is no non-surgical treatment for an epiretinal membrane.
Vitrectomy
Vitrectomy surgery is usually done on an outpatient basis under local anesthesia. The surgery involves making very small incisions in the white part of the eye (sclera) 4 mm behind the edge of the cornea. While looking at the eye through a microscope, the surgeon may use a variety of specialized instruments to work inside the eye. First, the vitreous gel is removed and replaced with a specially designed saline solution. The surgeon can “pull” the membrane off the surface of the macula. After the surgery, very fine absorbable sutures close the incisions.
Newer surgical techniques and instruments may allow the surgeon to perform surgery in some cases through tiny “self-sealing” incisions that do not require sutures. This new technique allows the eye to heal faster with minimal post-operative eye irritation. The eye remains bandaged until the next day.