Epiretinal Membrane

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Contents

Disease Entity

Macular Pucker ICD-9 code 362.56. Numerous terms have been used to describe this entity including: Epiretinal membrane, epimacular membrane, surface-wrinkling retinopathy, cellophane maculopathy, and preretinal macular fibrosis.

Disease

An epiretinal membrane (ERM) is a fibrocellular tissue found on the inner surface of the retina. It is semi-translucent and proliferates on the surface of the internal limiting membrane.

Etiology and Risk Factors

Idiopathic ERMs is the most common presentation. Secondary ERMs occur in association with retinal vascular diseases, ocular inflammatory disease, trauma, intraocular surgery, intraocular tumors, and retinal tear or detachment.

Other risk factors include age, posterior vitreous detachment, and history of ERM in the fellow eye.

The mean age of ERM diagnosis is 65 years old.[1] The incidence of developing an ERM in the primary eye is 1.1% per year. The incidence of developing an ERM in the fellow eye is 2.7% per year.

General Pathology

Retinal glial and retinal pigment epithelial cells are the major components. Fibrous astrocytes, fibrocytes, myofibrocytes, and macrophages can also be identified in pathological analysis.

Pathophysiology

It has been hypothesized that residual cortical vitreous secondary to a posterior vitreous detachment or partial separation of the posterior hyaloid allows proliferation of glial cells.

Inflammatory mediators also promote fibrocellular growth especially in the setting of secondary ERM formation.

Primary prevention

There are no preventative measures for idiopathic ERMs. The risk of secondary ERMs can be reduced in some cases by appropriately manage the underlying cause.

Diagnosis

This is a clinical diagnosis based on history and clinical exam, including slit lamp and dilated fundus examination. In some cases, Optical Coherence Tomography (OCT) is useful in the diagnosis and management of this condition.

History

Patients with ERMs typically present over the age of 50 and both sexes are equally affected. A careful history should be obtained to investigate for any of the risk factors mentioned above.

Physical examination

Slit lamp examination with dilated fundus examination and scleral depression are important to determine the presence and evaluate the severity of an ERM. Careful examination of the macular area is important to evaluate the ERM. However, paying attention the vitreous, retinal vasculature, and peripheral retina can provide insight as to the cause of the ERM in secondary cases.

Careful examination of the fellow eye is also recommended given that ERMs are bilateral in approximately 10-20% of patients.

Signs

A sheen or abnormal reflectivity of the macular surface is suggestive of an ERM. More advanced ERMs can become opaque.

Symptoms

Metamorphopsia, blurred vision, monocular diplopia, and micropsia can be noted with any macular pathology. The vast majority of patients with ERMs are asymptomatic.

Clinical diagnosis

Idiopathic ERMs affect the architecture of the macula. There can be blunting of the foveal contour or wrinkling on the retinal surface from membrane contracture. Most commonly it involves the foveal and parafoveal area.

Macular edema and/or pseudohole can be seen in association with an ERM. As the name implies, a pseudohole is not a full-thickness macular hole, but rather a hole or gap in the ERM that appears to be a retinal hole. Other associated signs include vascular tortuousity in the region of the ERM and/or intraretinal hemorrhages.

A posterior vitreous detachment is often noted which supports the pathophysiology of this entity.

Image:Epi1.jpg

Diagnostic procedures

Fluorescein angiography can be helpful in secondary cases of ERM including retinal vascular occlusions or intraocular tumors. Macular edema can be confirmed with angiography, as well.

OCT has become increasingly helpful in the diagnosis and management of this disorder. This high-resolution image can allow evaluation of the macula in cross section and three-dimensionally. OCT can be helpful detecting subtle ERMs as well as when associated with macular edema or other macular pathology.

OCT can also help guide management. Some cases of ERM with vitreomacular traction are subtle clinically and better detected with OCT. One of the great advantages of the OCT is the assessment of the vitreoretinal interface. This can provide additional information regarding therapeutic options and prognosis. In surgical cases, evaluation of each scan can elucidate the best approach for removal. Spectral domain OCT can also allow evaluation of the outer retinal layers/structure which may have barring on the physiologic outcome after an ERM removal.


Image:Epi2.jpg

Laboratory test

No laboratory tests are indicated in cases of idiopathic ERMs.

Differential diagnosis

The clinical appearance of an ERM is fairly distinctive. However, macular hole, parafoveal telangiectasia, and macular edema must also be considered.

Management

General treatment

The most important issue in the management of idiopathic ERMs is the presence of visual complaints. Visual symptoms can be variable and sometimes independent of clinical severity.

Medical therapy

No medical therapy is indicated for idiopathic ERMs.

Medical follow up

See above.

Surgery

Epiretinal membrane surgery is the most common vitreoretinal surgery performed as reported by the Centers of Medicare and Medicaid Services.[2] Surgery involves a pars plana vitrectomy procedure with membrane peel. A number of different instruments can be used to facilitate removal including intraocular forceps, pick, diamond dusted instruments, as well as other instruments.

Surgical follow up

The follow up is similar for most eyes following pars plana vitrectomy surgery. Visual acuity improvement does not occur immediately in some patients. This is highly dependant on preoperative characteristics, duration of the ERM, as well as other factors. Most patients improve by 3-6 months postoperatively. However, some may experience improvement 1-2 years postoperatively.

Complications

The complications are similar to all eyes undergoing pars plana vitrectomy. In addition, macular surgery complications include intraoperative macular trauma and light toxicity.

Prognosis

The mean preoperative and postoperative visual acuity has been reported to be 20/110 and 20/55.[3] This data was a metanalysis of three studies reporting surgical results following small incision pars plana vitrectomy.

The recurrence of ERM has been estimated to be 1%.[3]

Additional Resources

References

  1. Fraser-Bell S, Guzowski M, Rochtchina E, et al. Five-year cumulative incidence and progression of epiretinal membranes: the Blue Mountains Eye Study. Ophthalmology 2003;110(1):34-40.
  2. Gillis K. Medicare Physician Payment Schedule Services for 2001 - A Summary of Claims Data. In: Physician Marketplace Report. Chicago: American Medical Association, 2003.
  3. 3.0 3.1 Gupta OP, Brown GC, Brown MM. A value-based medicine cost-utility analysis of idiopathic epiretinal membrane surgery. Am J Ophthalmol 2008;145(5):923-8.
Original article contributed by: Omesh P. Gupta, MD, MBA
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