What is an epiretinal membrane?
In most cases the development of an Epiretinal Membrane appears to be related to normal aging changes inside the eye. In some cases, it can be related to other conditions such as diabetes, blockage of blood vessels, inflammation or following retinal surgery. Epiretinal membranes are not related to Macular Degeneration. Epiretinal Membranes do not usually affect the other eye. They are quite common and affect up to 8% of people in later years.
It is a translucent cellular membrane that develops over the macula (the central part of the retina responsible for vision of detail and movement). These cells are normally derived from the retina but may also be derived from deeper layers, such as the pigmented epithelium. These cells secrete collagen and form a mesh; when this membrane contracts, it distorts retinal tissue, giving rise to folds and wrinkles on the surface of the macula that affect its function.
Symptoms of epiretinal membrane
This pathology may be asymptomatic, though the main symptoms that reveal the presence of an epiretinal membrane are loss of visual acuity, distortion of images (metamorphopsia), micropsia (seeing objects smaller), diplopia (seeing double), aniseiconia (seeing objects of different size in each eye) and vision loss.
Assessment for Epiretinal Membrane. Mr Mookhtiar is able to detect an Epiretinal Membrane during an eye examination following the use of eye drops that temporarily make your pupils large. Sometimes, a special scan of the back of the eye may be needed to confirm the presence of an Epiretinal Membrane. Mr Mookhtiar will assess your symptoms to help you decide whether to proceed with surgery.
If the epiretinal membrane is not treated, it may lead to loss of central vision; however, it will never lead to total vision loss because only the macula is affected. Hence it is important to undergo annual reviews.
What are the causes of epiretinal membrane?
There are different factors that can cause epiretinal membrane, though the most frequent is posterior vitreous detachment (ageing process of the gel inside the eye, usually appearing in people aged over 50 years). Other causes are retinal detachment, vascular diseases, intraocular inflammation and severe ocular traumatic injury.
Treatment of the epiretinal membrane
The epiretinal membrane may be monitored at regular intervals, but if the symptoms worsen, the only way to treat it is to remove the membrane surgically. This is achieved by an operation called a Vitrectomy, where specialised instruments remove the jelly-like substance that normally fills the centre of the eye, called vitreous. The removal of the vitreous inside the eye does not cause any permanent harm, apart from speeding up the development of a cataract. The vitreous is replaced by natural fluid produced inside the eye. In some cases, the surgeon has to leave a special gas bubble inside the eye which disappears on its own after a few weeks.
The operation for Epiretinal membrane removal usually takes under an hour and can be performed using a local anaesthetic injection with the patient remaining comfortable and awake during the procedure. It is very important for the patient to stay still, especially during the very delicate manoeuvres when the membrane is removed using fine forceps.
Following membrane removal, the vision is typically more blurred and it can take months for it to improve. The operation is usually successful in reducing the distortion in vision due to an Epiretinal Membrane. If the vision had not been distorted prior to Epiretinal Membrane removal, improvement in the sharpness of vision and reading is less predictable.
Risks of Surgery for Epiretinal Membrane Removal
Surgery for Epiretinal membrane removal speeds up the onset of cataract, which is a very treatable cause of worsening vision. Sometimes, an early cataract is removed at the same time as the membrane removal to spare the patient from cataract surgery in the near future. Epiretinal membrane removal carries the risk of 1 in 50 cases of ending up with significantly worse vision and 1 in 50 of requiring further surgery to deal with recurrent Epiretinal membrane or other complications of surgery such as retinal detachment. The risk of serious complications of Epiretinal membrane removal is about 1 in 1000 cases, where the eye becomes totally blind due to a bleed during surgery or an infection after surgery. Some patients may develop persistently high eye pressure, which can damage the nerve of the eye causing vision loss. This condition is called Glaucoma and can affect 1:100 patients following this type of surgery. It may require long term use of eye drops and sometimes glaucoma surgery in order to preserve vision.
What should I do following surgery?
Following surgery, you will be given eye drops to use for a few weeks, which will help the eye settle from surgery. The operation does not require staying in hospital longer than one night and patients are typically reviewed in clinic a couple of weeks after surgery. On some occasions, you may be asked to position your head in a certain way for some part of the day for a number of days. Otherwise, you can do most daily activities although you should abstain from unhygienic environments and anything that puts the eye at risk of injury.
How much time off work will I need?
Most people will need at least two weeks off work after surgery. The amount of time off work will depend on the kind of work you do and the kind of surgery that is done.