**4. ERM clinical findings**

diseases and enabling novel therapeutic options. OCT evaluation has become the routine imaging method for any vitreomacular disease in retinal evaluation of the patients in the clinics as well as the essential component in any study design regarding the treatment of retinal diseases. Recently, OCT has also been integrated into our operating rooms by supporting our

**Epiretinal membrane (ERM)**, which has also been named as epimacular membrane, cellophane maculopathy, preretinal macular fibrosis, and surface-wrinkling retinopathy, is a disorder of the vitreomacular interface. It is a fibrocellular membrane lying on the inner surface of the retina, which can cause decreased vision and/or metamorphopsia. Epiretinal membranes are frequently seen in an aging eye, especially after posterior vitreous detachment (PVD), and its prevalence increases with increased age [2]. The mean age of ERM diagnosis is 65 years old, affecting both sexes equally [3]. The prevalence of ERM varies from 2.2 to 28.9% depending on the population being studied [4, 5]. The incidence of developing an ERM in the primary eye is 1.1% per year, whereas its incidence in the fellow eye is 2.7% per year. Bilaterality changes

Epiretinal membranes are classified as idiopathic, and secondary regarding their etiology. Idiopathic ERM is the most common form. Secondary ERMs are associated with posterior uveitis, retinal vascular occlusions, diabetic retinopathy, trauma, retinal tear or detachment, and their repair, argon laser photocoagulation, cataract surgery [6]. Other risk factors include age, PVD, and history of ERM in the fellow eye. Secondary ERMs tend to occur in younger patients [7]. Clinically, ERMs are classified as cellophane macular reflex or preretinal macular fibrosis according to their severity [8]. Cellophane macular reflex is an early form, including a thin transparent membrane overlying the macula usually clinically asymptomatic, whereas preretinal macular fibrosis is the later form with thickened and contracted membrane causing

The diagnosis of PVD, which is defined as separation between the posterior vitreous cortex and the internal limiting membrane (ILM) of the retina, has been described in up to 95% of cases of idiopathic ERM [9]. Residual cortical vitreous secondary to a PVD or anomalous PVD leading to vitreoschisis with only partial separation of the posterior hyaloid remain to be factors allowing proliferation of glial cells. Inflammation is a central component of disorders leading to secondary ERMs, with increased inflammatory mediators promoting fibrocellular growth. Retinal glial cells, hyalocytes, fibroblasts, myofibroblasts are the predominant cell types found in the ERMs. Retinal pigment epithelial cells, macrophages, T-, and, B-cells are identified in secondary ERMs [6]. Extracellular matrix production and remodeling are

decision-making during vitrectomy known as intraoperative OCT (iOCT).

between 19 and 31% of the eyes, and mostly with asymmetric involvement.

**2. ERM classification**

66 OCT - Applications in Ophthalmology

visual impairment in most eyes.

**3. ERM-pathogenesis**

Epiretinal membrane is relatively common especially after 60 years of age, and both sexes are equally affected. A careful history should be obtained to evaluate for secondary causes of ERMs. The patient more often presents without any symptoms diagnosed on a routine ophthalmological examination especially with very early and thin membranes. He can also present with the symptoms of metamorphopsia, blurred vision, monocular diplopia, and micropsia [13]. Contrast sensitivity is frequently decreased.

In the ophtalmological examination, best corrected visual acuity (BCVA) is noted. Amsler grid test is also performed. On slit lamp examination lens status with any form of cataract is noted. Dilated fundus examination is performed. Careful examination of the macular area for any subtle membrane is important as it can easily be missed on routine examination. The presence of PVD is noted. Detailed examination of the peripheral retina for any missed retinal tear should be performed. The examination of the vitreous for any cells, and of retinal vessels for secondary causes should also be performed. The same examination should also be done for the fellow eye.

Clinically, an ERM can be seen as a loss in the normal convex contour of the fovea, an abnormal reflectivity of the macular area, or as wrinkling on the macular area in fundoscopy. As cellophane macular reflex is a thin membrane without causing any distortions in the retina, it usually does not cause visual impairment, and usually observed as an incidental finding in routine fundus examination. More advanced ERMs classified as preretinal macular fibrosis can be easily seen as they are often opaque and whitish in color, obscuring the underlying retina (**Figure 1**). There may be traction, or tortuosity in the vessels in thick membranes

**Figure 1.** Epiretinal membrane. Color fundus image of the left eye showing grayish tissue over the macula obscuring the details of the underlying retina and causing tortuosity in the retinal vessels. The patient complains of blurred vision and metamorphopsia.

sometimes with intraretinal hemorrhages, or exudates in severe cases. Macular edema can be observed. Preretinal macular fibrosis usually distorts the retina causing visual impairment in nearly 80% of cases [14]. ERMs can give an impression of a macular hole, when there is proliferation on both sides of the fovea, but a gap in the center which looks like a macular hole gives the name as a "pseudohole". The best method to examine it is with a contact macular or a goniolens, though it may be difficult in a busy daily practice. ERMs can also be associated with lamellar macular holes or less commonly with macular holes. The usual course is slow progression over the years with VA decreasing to 0.1.
