Epiretinal
Membranes
The Eye Doctors at Auckland's Eye Institute are
leaders in ophthalmology, so you
can trust their experience in the diagnosis
and treatment of an Epiretinal Membrane.
Auckland's Eye Institute have a purpose-built day-stay
hospital and their Specialist Eye Doctors are leaders in
ophthalmology.
What is an epiretinal
membrane?
The retina is a thin delicate tissue
that lines the inside of the back of the eye. It is nerve tissue
that senses light that shines into the eye, converts the light
into an electrical signal and sends this signal through the optic
nerve to the brain, which then processes the information resulting
in sight. The macula is the very central area of the retina that
gives us sharp central vision and reading vision, as well as most
of our colour vision.
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| An
epiretinal membrane – in
colour and more obviously
in black and white |
|
An epiretinal membrane is a thin sheet
of fibrous tissue that can develop
on the surface of the macula. When
a membrane develops on this very
thin, delicate
macular area of the retina it acts like a film through which it is harder to
see than normal. Furthermore, it may contract just as scar tissue does, pulling
on the retina and distorting it, causing not only distortion of the vision
due to distortion of the macula, but also causing the retina to become swollen
and
work less well. Because it is often the distortion of the macula that is the
most obvious feature of this problem, it is sometimes also called a macular
pucker, premacular fibrosis, surface wrinkling retinopathy or cellophane maculopathy.
What
causes an epiretinal membrane?
In most cases an epiretinal membrane is idiopathic,
that is it develops in an eye with no history of any previous
problems. It is not due to anything the afflicted individual has
done, but instead is caused by natural changes in the vitreous
gel overlying the macula that cause normal biological cells derived
from the retina and other tissues within the eye to become liberated
into the vitreous gel and eventually settle onto the surface of
the macula. In some cases these cells may begin to proliferate
into a “membrane”. In many instances this membrane
remains very mild and does not have any significant effect on
the macula or the person's vision. In other cases however, the
membrane may slowly become more prominent, eventually creating
a disturbance in the retina that leads to visual blurring and/or
distortion in the affected eye, particularly if the membrane contracts.
However, an epiretinal membrane can also
develop if cells are liberated into the eye by a previous problem,
such as a retinal tear or detachment, trauma, inflammatory disease,
blood vessel abnormalities, or other conditions. These are called
secondary epiretinal membranes; they have the same effect on vision
as the idiopathic type and are treated in the same way.
How
does an epiretinal membrane affect vision?
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| An OCT scan
showing an epiretinal membrane
distorting the macula |
|
Many
epiretinal membrane are mild and have little or no effect on vision.
However, if the
epiretinal membrane grows more prominent
and contracts, causing mechanical distortion
(“wrinkling”) of the macula , blurring and/or
distortion of the central portion of
vision in the affected eye may occur
and may get slowly worse over time.
An epiretinal membrane does not make
an eye go completely blind. It typically
affects only the central area of vision
and does not cause a loss of the peripheral
(side) vision.
Is an epiretinal membrane the same as macular degeneration?
No! An epiretinal membrane and macular degeneration
are completely different conditions affecting the retina
Is there treatment for an epiretinal membrane?
Yes. An epiretinal membrane can be treated
with surgery. However, not all epiretinal membranes require
treatment. Treatment is unnecessary if the epiretinal membrane
is mild, stable and having little or no effect on vision.
Only cases in which the membrane is causing problems require
consideration of surgery. However, it an epiretinal membrane
is getting worse it is better to remove it sooner rather
than later, as severe mechanical distortion of the macula
may cause permanent changes that removing the membrane may
not improve or only improve to a limited extent.
There is no other treatment apart from surgery
for an epiretinal membrane.
What is epiretinal membrane surgery like?
The surgery for a macular hole is called
a vitrectomy. This surgery is usually done as a day (outpatient)
surgery using a local anesthesia, and takes up to an hour. The
surgery consists of making very small ports through the white
part of the eye (the sclera) 3 mm behind the edge of the cornea.
Newer surgical techniques and instrumentation allow the surgeon
to perform the surgery through tiny “self-sealing” incisions
that do not require sutures. This new technique allows faster
healing of the eye with minimal or no post-operative ocular
irritation.
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| An OCT
scan following surgery showing
a normal, not distorted macula |
|
While looking into the eye through a microscope
the surgeon can use a variety of very specialised
instruments placed through these incisions
to work within the eye. The vitreous gel
is first removed as is the posterior hyaloid
membrane which is at the back of this gel.
This holds the gel together like the skin
of a balloon filled up with water; removing
it also removes any floaters that one may
have. The vitreous gel is then replaced with
a specially designed saline
solution. The surgeon can then “peel” the epiretinal
membrane from the surface of the macula.
Sometimes the surgeon also peels a very thin
membrane (the "internal
limiting membrane of the retina") from the surface of the
macula which can become puckered by the epiretinal
membrane sitting on top of it. Steroid treatment
or air are commonly placed inside the eye
to hasten the rate at which the retina recovers
from having been distorted by the membrane,
and laser and freezing (cryotherapy)
treatment is usually also used to secure
the peripheral retina in place.
What is the postoperative care like after epiretinal
membrane surgery?
A patch is worn over the eye until the morning
after surgery. Eye drops (an anti-inflammatory and an antibiotic)
are then used several times each day for up to 4 weeks after surgery.
Patients can usually resume normal non-strenuous physical activities
the day after surgery. How quickly the patient can drive, return
to work, perform fine visual tasks, or engage in strenuous activities
will vary from person to person.
How
much will my vision improve after surgery?
The amount of visual improvement will vary
depending on the age and anatomic characteristics of the epiretinal
membrane, how significantly the vision has become affected by
the epiretinal membrane, and the presence of any other ocular
abnormalities that might limit vision. It is not unusual to recover
vision of 6/6 or 6/9 after successful epiretinal membrane surgery,
and the distortion improves in 90% of patients. However, some
individuals may have more limited improvement in vision, especially
if the membrane had been there for a long time and the vision
had already become very poor, and a small percentage of people
may not improve very much at all even with successful surgery.
It takes anywhere from 3 months to 1 year for vision in the affected
eye to reach it's maximal improvement.
What complications may occur as a result of epiretinal
membrane surgery?
Any surgical procedure carries a risk of
complications and this surgery is no exception.
There are 3 major potential complications of surgery:
- Post-operative
infection (endophthalmitis): This is an infection that develops inside
the eye after ocular surgery. Though
most infections can be effectively treated if identified at
an early
stage, there is a risk that an infection
can create severe damage that could
lead to blindness in the affected eye. Fortunately,
endophthalmitis is rare, occurring
in only 1 of 1000 cases.
- Retinal detachment: Retinal detachment can occur
spontaneously in an eye that has never
had surgery of any type. However, an
eye that has undergone surgery is at greater risk of developing
retinal detachment. A retinal detachment
may occur relatively soon after surgery,
but
may occasionally develop months or
years later, and can lead to blindness if not repaired.
Fortunately nearly all retinal detachments
can be between 1 and 2 out of 100 cases.
- Cataract: Cataracts, or haziness in the lens of the eye, commonly
develop as a natural consequence of
aging
of the eye. However, a cataract will
often develop or progress to a point
of significant visual blurring sufficient to warrant
cataract surgery more quickly after
having had this surgery. This is not a concern
if the patient has had cataract surgery
prior to having a vitrectomy surgery.
To make an appointment, or
to find out more information, fill out our enquiry
form, or contact Eye Institute's
friendly team on free phone 0800 393 527.
Affiliated provider benefit to Cataract Patients
- no need for prior approval
- no money up front for surgery
- Southern Cross pays us directly
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