Refractive Eyecare — June2011
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RETINA: Advances in Epiretinal Membrane Treatment
Michael D. Bennett, MD

As surgery becomes less invasive, it can be performed earlier in the course of the disease, improving the chance for a good outcome.

Epiretinal membrane,also known as epimacular membrane, macular pucker, wrinkled retina, and preretinal membrane, is a wrinkling of the surface of the retina, congregating around the macula, which can lead to a distortion in vision if left untreated. It occurs in an estimated 7% of the population and most commonly in adults over 55 and those with diabetes. The prevalence in individuals aged 75 is an estimated 20%.

Epiretinal membrane can be caused by any disruption to the inside of the eye and is associated with injury, vitreous detachment, retinal tears, retinal detachment, post-intraocular surgery, inflammation, and vitreous hemorrhage. However, many cases are idiopathic.

Epiretinal membranes are avascular, fibrocellular membranes that occur on the inner surface of the retina. Some reports suggest that following a retinal tear or a posterior vitreous detachment, glial cells from the inner layers of the neurosensory retina proliferate via breaks in the internal limiting membrane. Typically a membrane break leads to swelling and inflammation, and potentially scarring of the tissues on the surface of the retina. The retina can be described as having a smooth, shiny surface, like a sheet of Saran™ Wrap. When this scar tissue forms, it contracts, causing that smooth surface to become wrinkled and appear more like a crinkled sheet of cellophane. This crinkling can distort vision, resulting in metamorphopsia.

Common Causes

Posterior vitreous detachment is a significant cause of epiretinal membrane, seen in 75% to 93% of cases.1 When the vitreous breaks free of the back of the eye, it can leave behind fibroglial cells that can attach to the retina and proliferate, forming sheets of membranes over the retinal surface. Vitreous hemorrhage and inflammation may also cause epiretinal membranes. Even when the vitreous is attached, it can cause vitreomacular traction, pulling on the retina in almost the same fashion.

Diabetics are prone to epiretinal membrane because their glucose fluctuations make them susceptible to endothelial and pericyte cellular damage within the blood vessels. This leads to oozing that can produce scar tissue.

Diabetics are at risk of severe tractional retinal detachments, a very aggressive form of epiretinal membrane. If a patient has a retinal tear, the liberated cells can land on the surface of the macula or the retina, where they proliferate. Epiretinal membrane occurs in 3% to 8.5% of eyes after retinal detachment surgery.


Epiretinal Diagnosis And Treatment

Symptom history including mild distortion and blurring

Advanced symptoms include metmorphopsia, blurred vision, or poor current vision

Uncorrectable vision poorer than 20/20 is the new standard

Gass grading system

OCT for physical diagnosis of
— Membrane thickness
— Puckering
— Edema

Treat earlier if edema occurs

Lower-risk surgery changes risk/benefit ratio


Improvements in Detection

With a thorough symptom history and clinical exam, most ophthalmologists and optometrists can detect epiretinal membranes. Assessment begins with a symptom history, although symptoms may be subtle at first, such as mild distortion or blurring. If the condition has progressed, it can cause metmorphopsia, blurred vision, or poor current vision. It is useful to determine the severity of those symptoms and the degree to which they affect the patient’s daily activities.

If the patient is not correctable to 20/20, it is important to explore the possible causes, such as a cataract or a problem on the retinal surface. In the past, we were concerned if a patient could not be corrected to 20/30 or better, but now we should be concerned if they are not 20/20.

Gass developed a classification system based on physical exam Table 1).2 Grade 0 membranes are translucent, Grade 1 have irregular wrinkling or fine super ficial radiating folds, Grade 2 membranes tend to be opaque, thick and often accompanied by macular puckering, edema, hemorrhages, and possibly a localized retinal detachment.

Epiretinal membrane was once thought to be a complication of cataract surgery, but may be present prior to surgery.³ Many surgeons are now including OCT in their pre-cataract assessment. OCT is also making its way into mainstream optometric practice.4 OCT can detect macular thickening, vitreomacular traction, and edema, aiding in diagnosis and in explaining to the patient what is occurring. The severity of symptoms a patient experiences depends on the thickness of the membrane, the location of the wrinkling, whether there is retinal detachment, and edema. Patients who appear to have epiretinal membrane should Exbe referred to a surgeon to discuss the risks and benefits of surgery vs a waitand- see approach.


TABLE 1 Gass Classification of Epiretinal

Grade 0
Cellophane maculopathy

* Cellophane-like sheen seen on ophthalmoscopy
* No associated visual distortion

Grade 1
Crinkled cellophane Maculopathy

* Membrane causes irregular wrinkling of inner retinal surface
* Fine superficial folds extend from membrane margins
* In severe wrinkling, paramacular vessels may be pulled towards the fovea in a
corkscrew formation

* Not typically seen
- Cystoid macular edema
- Retinal hemorrhage
- Exudates
- Retinal pigment epithelial disturbances

* Patients report visual disturbance
* Visual acuity often 20/40 or worse

Grade 2
Macular pucker

* Membrane thick and opaque
* Full thickness puckering of the macula may be present

* Often found
- Edema
- Small hemorrhages
- Cotton-wool spots
- Sometimes, localized retinal detachment

* Vision severely affected (acuity often < 20/200)


When to Treat

As surgery becomes less invasive, the threshold for operating is lowered, and we are tempted to perform surgery earlier. Historically, we waited until the best corrected vision progressed toward 20/40 before operating, but this is changing as the risk/ benefit ratio shifts.

Surgery should be decided on a case by case basis, depending on the patient, his or her visual needs, and the extent of the damage. The decision to operate used to be vision-driven. But now OCT can determine whether the

Surface of the retina is distorted and whether there is retinal edema. We now understand that the longer the retinal edema persists, the more likely it it is to start to affect the photoreceptors. Edema is an indication that surgery should be considered earlier to avoid permanent photoreceptor damage.

Surgical Procedures

The goal of surgery is to prevent further loss of vision and to get back at least half of what has been lost. If the patient is 20/40, it is reasonable to expect a 20/30 or 20/25 outcome— and possibly 20/20. We cannot yet predict how well individual patients will do, except that those with a more advanced condition have a lower chance of recovering all of their vision.

Pars plana vitrectomy is performed to remove the vitreous, preventing vitreous contraction and eliminating vitreous traction on the macula. In a vitrectomizing procedure, the vitreous gel is replaced with either a salt solution or gas, allowing the epiretinal membrane to be peeled away from the surface of the retina. However, vitrectomy has been shown to increase the rate of cataract formation threefold after a follow-up of 6 months, and some surgeons instead perform no-infusion/ no-vitrectomy membrane peeling, although this is controversial, as it often leads to floaters postoperatively.

In epiretinal membrane peeling, the membrane is lifted off the retinal surface using a pick or fine forceps. If the epiretinal membrane is a single continuous sheet, it may peel off easily, like lifting a piece of paper. But membranes that form in little strips, which happen more commonly in diabetics, are more difficult to remove.

After membrane removal, the surgeon needs to look for retinal breaks to avoid retinal detachment postoperatively.


The most common complications include intraocular bleeding and retinal breaks. Following surgery, as many as 75% of treated eyes ex Perience accelerated progression of nuclear sclerosis of the lens, and most patients have to undergo cataract removal within 2 years to maximize the benefits of membrane peeling. Postoperative retinal detachment may occur in about 3% to 6% of patients, but this can be treated with a followup surgery. Postoperatively , the patient can expect vision to improve over a 3 to 6 month period. Patients should be monitored for recurrence.

On the horizon, understanding cellular metabolism and pathologic anatomic changes will provide a better idea of when to do surgery and how the eye will respond to the procedure.


A better understanding of the progression and risks of epiretinal membrane is leading to the earlier treatment of the condition to prevent permanent visual damage. Diagnosis is based on clinical symptoms, a physical exam, and increasingly on OCT findings such as edema and retinal distortions. The advent of sutureless vitrectomy surgery has made surgery a safer option with a lower risk of complications.


Michael D. Bennett, MD, is a vitreoretinal surgeon and associate professor in the department of surgery at the University of Hawaii John A. Burns School of Medicine. Freelance writer Laurie Tarkan assisted in the preparation of this article.


1. Kase S, Saito W, Yokoi M, et al. Expression of glutamine synthetase and cell proliferation in human idiopathic epiretinal membrane. Br J Ophthalmol. 2006;90(1):96-8.

2. Gass JDM. Macular dysfunction caused by epiretinal membrane contraction. In: Stereoscopic Atlas of Macular Diseases: Diagnosis and Treatment. Vol 2, 4th ed. St Louis, Mo: Mosby; 1997:938-50.

3. Contreras I, Noval S, Tejedor J. [Use of optical coherence tomography to measure prevalence of epiretinal membranes in patients referred for cataract surgery]. Arch Soc Esp Oftalmol. 2008 Feb;83(2):89-94.

4. Takashi T et al. Classification of epiretinal membrane based on findings by optical coherence tomography. Japanese Journal of Clinical Ophthalmology. 2002;56:1005-9.