Membranes

BASICS


DESCRIPTION


• Epiretinal membranes are also known as macular pucker, cellophane maculopathy, and surface wrinkling retinopathy.


• It is a thin layer of tissue found on the surface of the retina.


• It can cause distortion of the retina and lead to decreased vision.


– It is associated with abnormal vitreous separation and sometimes presents with vitreomacular traction.


Geriatric Considerations


Epiretinal membranes (ERM) most commonly occur in the elderly population.


Pediatric Considerations


Very uncommon as a primary diagnosis. Most likely associated with other conditions that can cause macular dragging and ERM formation due to glial abnormalities/proliferation and traction.


Pregnancy Considerations


Intervention and full evaluation can usually be postponed until after the birth of the infant.


EPIDEMIOLOGY


Incidence


• ERM is a common condition that is usually benign and causes no visual symptoms and does not require surgery.


• Although bilateral in 20–30% of cases, it is often asymmetric.


Prevalence


• Most likely to be found in patients over 50 years old.


• ERMs occur in 2% of eyes in patients aged 50 years, and the prevalence increases to 20% of eyes at 75 years of age.


RISK FACTORS


• Gender (women).


• Elderly.


• History of retinal laser, ocular surgery, or trauma.


• Diabetes.


• Retinal vascular conditions.


• History of vitreous hemorrhage.


• History of intraocular inflammation.


Genetics


No genetic predisposition.


PATHOPHYSIOLOGY


• ERM forms due to an abnormal proliferation of glial cells (primarily fibrous astrocytes but also Muller cells, fibrocytes, myofibroblasts, macrophages, and hyalocytes) on the surface of the retina.


• Glial cells usually access the retinal surface following a posterior vitreous detachment (PVD) but can also migrate to the retina prior to PVD.


• Traction may result from the cells assuming myofibroblastic properties exerting traction on the retinal collagenous scaffold and ultimately leading to distortion and decreased vision.


ETIOLOGY


• Abnormal cellular proliferation on the surface of the retina causes the visual appearance of an ERM.


– Primary idiopathic ERM occurs with no history of trauma, surgery, inflammatory disease or other ocular disease.


– Secondary ERM occurs due to ocular inflammation, trauma, surgery, or retinovascular disease.


COMMONLY ASSOCIATED CONDITIONS


• Diabetes.


• Retinal vascular diseases.


• Ocular inflammation.


DIAGNOSIS


HISTORY


• Most are asymptomatic.


• Gradual worsening in vision.


• Monocular distortion in linear objects.


• Difficulty reading due to blurry vision.


• Diplopia or central photopsias.


PHYSICAL EXAM


• Biomicroscopic examination reveals the abnormal appearance of the surface of the retina.


• Subtle ERM may only appear like a glinting or irregular light reflex of the fovea.


• A contracting ERM can produce retinal striae due to traction on the internal limiting membrane (ILM).


• Traction results in visible tortuosity of the retinal vessels.


• Occasionally retinal hemorrhages, cotton wool spots, and commonly macular edema are visible.


DIAGNOSTIC TESTS & INTERPRETATION


Lab


Initial lab tests

No laboratory studies are needed to diagnose routine ERM.


Follow-up & special considerations

Amsler grid testing is useful in determining the symptomatic nature of the ERM.


Imaging


Initial approach

• Optical coherence tomography (OCT) can be useful to show objective evidence of retinal surface disease and underlying macular edema.


• OCT can also show abnormalities in retinal architecture such as edema and cystoid changes.


– ERM associated with significant CME may confer a poor visual prognosis.


Follow-up & special considerations

• Asymptomatic patients can be observed.


• Counseling patients in the use of Amsler grid.


• Prompt re-evaluation for worsening of symptoms is warranted since surgical intervention prior to induced abnormalities in retinal architecture confers a better ultimate visual prognosis.


Diagnostic Procedures/Other


• Fluorescein angiography (FA) is useful to evaluate the retina for any underlying retinovascular diseases and evaluating for macular leakage.


– Significant vascular leakage or capillary nonperfusion helps in counseling patients about decreased visual prognosis following surgery.


Pathological Findings


• Extensive cystoid macular edema confers a poor visual prognosis after surgical intervention.


• Thin and irregular photoreceptor layers can be visualized on spectral domain-OCT (SD-OCT).


DIFFERENTIAL DIAGNOSIS


• Fibrotic fronds from proliferative diabetic retinopathy or ischemic vein occlusions.


• Incomplete partial posterior vitreous detachment with adherent posterior hyaloid.


TREATMENT


MEDICATION


First Line


When associated with idiopathic edema, topical steroids, topical NSAIDs or subtenon injection of triamcinolone can be considered.


Second Line


Not usually treated with any other medications.


ADDITIONAL TREATMENT


General Measures


Presence of an ERM does not require surgical intervention unless there are significant symptoms or worsening retinal appearance on OCT.


Issues for Referral


Patients who are symptomatic should be referred to a vitreoretinal surgeon for evaluation.


Additional Therapies


Underlying associated conditions such as age-related macular degeneration and diabetes should be addressed prior to entertaining surgical intervention.


COMPLEMENTARY & ALTERNATIVE THERAPIES


• When associated with cystoid edema of the retina, primary treatment to the underlying edema can be considered.


• Current clinical trials are studying the effect of intravitreal injection causing medical vitreolysis to facilitate the release of focal vitreomacular traction. (1)[A].


SURGERY/OTHER PROCEDURES


• Vitrectomy surgery with membrane peel is recommended for patients who are symptomatic from visual distortion or with vision worse than 20/40.


• Some vitreoretinal surgeons advocate attempted removal of the ILM during ERM removal to decrease the chance for recurrent ERM formation (2)[B], (3)[B].


– Recent advances in minimally invasive vitrectomy systems have led to quicker visual recovery and higher patient satisfaction.


ONGOING CARE


FOLLOW-UP RECOMMENDATIONS


• Depending on underlying disease and appearance, routine follow-up is needed.


• Patients without symptoms can be observed.


• Initial timely follow-up is indicated but if no symptoms occur, follow-up can be extended.


• ERM can commonly stay dormant for many years; however acute PVD or surgery may incite contraction and cause symptoms.


Patient Monitoring


• Amsler grid monitoring is essential.


• Distortions in vision should warrant re-evaluation.


DIET


No specific diet is recommended.


PATIENT EDUCATION


• Amsler grid testing is imperative to follow the severity of distortion.


• Any new symptom should warrant re-evaluation.


PROGNOSIS


• Asymptomatic ERM that are observed and do not require intervention have an excellent visual prognosis.


• Symptomatic ERM that require surgery usually results in visual improvement with 80–90% improving 2 or more Snellen lines.


• Most patients can regain half of the vision lost due to the ERM distortion.


– ERM surgery usually results in greatly diminished metamorphopsia, however few eyes will regain 20/20.


– Preoperative vision is a good indicator of postoperative visual prognosis.


COMPLICATIONS


• Cataract formation: Most common.


• Peripheral retinal breaks:


– 1–6%.


– As high as 13.9% in recent study of 20 gauge vitrectomy (4)[C].


• Retinal detachment: 1–7%.


• Recurrent ERM: 0–5%.


• Retinal phototoxicity.


• Endophthalmitis is rare.



REFERENCES


1. MIVI TRUST Clinical Trial, Phase III study for focal VMT using microplasmin for intravitreal injection-traction release without surgical treatment, Thrombogenics. 2010


2. Shimada H, Nakashizuka H, Hattori T, Mori R, Mizutani Y, Yuzawa M. Double staining with brilliant blue G and double peeling for epiretinal membranes. Ophthalmology 2009 Jul; 116(7):1370-6.


3. Kwok A, Lai TY, Yuen KS. Epiretinal membrane surgery with or without internal limiting membrane peeling. Clin Exp Ophthalmol. 2005 Aug:33(4);379-85.


4. Ramkissoon YD, Aslam SA, Shah SP, Wong SC, Sullivna PM. Risk of Iatrogenic Peripheral Retinal Breaks in 20-G Pars Plana Vitrectomy. Ophthalmology 2010 May 13 [E-pub ahead of print]

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Membranes

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