| EPIRETINAL MEMBRANE  SIGNS AND SYMPTOMS
Epiretinal membrane is known by many names in clinical and educational circles, including
preretinal membrane, idiopathic preretinal macular gliosis, cellophane maculopathy,
macular pucker and surface wrinkling retinopathy. In early stages, epiretinal membrane may
be asymptomatic, or it may create only a mild reduction in acuity. Its progression may
cause metamorphopsia and lead to severe visual impairment.
The ophthalmoscopic picture of this disorder ranges from a fine,
glistening membrane overlying the macula (cellophane maculopathy) to a thickened, whitish
tissue that obscures the underlying vasculature.
As the epiretinal membrane progresses, traction at the level of the
internal limiting membrane (ILM) creates a puckering effect-you may see retinal folds
radiating outward from the macula. Adjacent retinal vessels which course under the ILM
often assume a "corkscrew" pattern, which is quite dramatic with fluorescein
angiography. In very severe cases, macular edema and even retinal detachment have been
known to occur.
PATHOPHYSIOLOGY
Epiretinal membrane formation occurs as a result of retinal glial cell proliferation along
the surface of the ILM. Small, focal defects in the ILM allow these cells to "break
through" to the retinal-vitreous interface and reproduce, creating a thin veil of
tissue. Epiretinal membranes have been found in association with retinal vascular
diseases, retinal breaks and detachments, ocular trauma, uveitis, and following retinal
cryopexy, laser photocoagulation, and intraocular surgery. Often, the membranes are seen
following posterior vitreous detachment, or they may occur idiopathically in patients over
50 years of age.
MANAGEMENT
In most cases, little can be done to improve acuity. Most patients, fortunately, suffer
only a minimal reduction of acuity or slight metamorphopsia. Reassure patients as to the
nature of the disorder and follow up periodically, using an Amsler grid for home
monitoring of progression. In severe cases, vision may drop to 20/100 or worse; this may
indicate the need for vitrectomy and surgical peeling of the membrane. This procedure is,
as one might imagine, very intricate, and is reserved for those patients for whom there
are no alternatives.
CLINICAL PEARLS
Suspect epiretinal membrane in older patients where
decreased acuity or visual distortion cannot be accounted for by lenticular changes,
macular degeneration or optic atrophy.
Early identification of epiretinal membranes requires
careful inspection with a slit-lamp fundus lens (78D, Hruby or Goldmann). If you are
confused as to the true etiology, or if you suspect macular edema, order a fluorescein
angiography. Typical fluorescein patterns in epiretinal membrane show
"corkscrew" distortion and dragging of the retinal vessels at the posterior
pole, with a characteristic diminishing of the foveal avascular zone. If there's edema,
you'll see hyperfluorescence within the macula during the late transitory phase.
Other reports in this section
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