Epiretinal Membranes (ERMs) & Cataract Surgery
An epiretinal membranes is a thin scar-like, semi-translucent, fibrocellular tissue It is semi-translucent tissue (composed of retinal glial cell, retinal pigment epithelial cells, fibrous astrocytes, fibrocytes, myofibrocytes, and macrophages) that grows on the inner surface of the retina.
The retina is the lining at the back of the eye that is responsible for vision. If this scar-like tissue grows directly over the macula, which is the tiny portion of the retina that is responsible for sharp, central vision, the vision may not be 20/20. Some cases of mild ERMs may occur which do not limit vision significantly (vision can still be 20/20 but distorted sometimes). Other ERMS begin to contract and cause a macular hole.
A PAM (Potential Acuity Meter) can determine if it is just the cataract affecting general vision or the Epiretinal Membran/ERM. If ERM small, might still have 20/20 after. Brightness acuity test (BAT): generally tells us how bad the cataract is. OCT (optical coherence tomography) tells us how significant ERM is.
The Frustration: still no guarantee what vision will be till after cataract surgery is completed and eye has healed (which can take weeks to months).
Most eye surgeons depending on severity would prefer to have the cataract removed first before removing the ERM given then risks in ERM surgery.
A great resource below:
Epiretinal Membrane
| Original article contributed by: | Omesh P. Gupta, MD, MBA |
|---|---|
| All contributors: | Sarah.C.Page.AAO and WikiWorks |
| Review: | Not reviewed |
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.
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.
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
- ↑ 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.
- ↑ Gillis K. Medicare Physician Payment Schedule Services for 2001 – A Summary of Claims Data. In: Physician Marketplace Report. Chicago: American Medical Association, 2003.
- ↑ 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.
