20 Vitreomacular Traction and Optical Coherence Tomography Classification



10.1055/b-0035-121735

20 Vitreomacular Traction and Optical Coherence Tomography Classification

Mehreen Adhi and Jay S. Duker

Diseases of the vitreomacular interface (VMI) are broadly classified as vitreomacular traction (VMT), full-thickness macular hole (FTMH), lamellar macular hole (LMH), and epiretinal membrane (ERM). 1 ,​ 2 ,​ 3 ,​ 4 ,​ 5 Over the past few years, an understanding of the anatomical changes at the VMI in both normal and pathological states has become possible with the widespread availability of optical coherence tomography (OCT). Recent advances in OCT technology, as well as innovations in surgical techniques and the recent availability of pharmacologic vitreolysis, have coalesced to enormously increase clinicians’ interest and understanding of diseases of the VMI.


Using spectral-domain (SD) OCT, multiple studies have characterized the findings associated with both the normal features of vitreous aging and the abnormal changes in VMI disease. 1 ,​ 2 ,​ 3 ,​ 4 However, much of the clinical practice and evaluation of emerging surgical and pharmacological therapies for these conditions have been hindered by a lack of a consistent and uniform nomenclature surrounding these conditions. Considering this unmet need, an international group of macular disease experts was convened in 2012 to develop a consensus system for classification of VMI conditions using SD OCT. 5 The result of this collaborative study is a new anatomical OCT-based classification of the VMI conditions: the International Vitreomacular Traction Study (IVTS) Group Classification System. 5 This anatomical, OCT-based classification of VMI findings and diseases permits a consistent terminology for these conditions such that a standardized reporting system is established, 5 and the diagnosis and management of VMI conditions using OCT are facilitated. It does not take into account the symptoms or clinical findings, however, and is strictly anatomically based using OCT.



20.1 OCT-Based Classification of Vitreomacular Adhesion


In the normal state, all eyes have a complete adhesion of the vitreous to the inner retinal surface at birth. As the eye ages, a complex series of events causes the vitreous cortex to detach from the inner retina. This phenomenon is called posterior vitreous detachment (PVD) and is a normal aging process. 1 ,​ 2 ,​ 5 ,​ 6 However, it can be accelerated by blunt trauma, inflammation, and intraocular surgery. PVD usually begins in the perifoveal region and progresses over many years to involve multiple sites in the peripheral fundus before finally coalescing into a complete separation of the vitreous cortex from the macula and the optic nerve, with the appearance of the Weiss ring. For the most part, this is a nonpathological process. In some eyes, the vitreous cortex detaches inadequately or incompletely from the inner retinal surface. This phenomenon is termed an anomalous PVD. 5 ,​ 6 ,​ 7 According to the IVTS Group Classification System, 5 an anomalous PVD is defined as a partial vitreous detachment with an anomalous persistent attachment in the macular region resulting in tractional distortion of the retina. An anomalous PVD may then lead to pathological features of VMI disease. 5 ,​ 6 ,​ 7


In the anatomical OCT-based IVTS Group Classification System, vitreomacular adhesion (VMA) is equivalent to a stage 1 PVD in the Uchino, Gaudric, and Johnson classification systems. 1 ,​ 2 ,​ 6 ,​ 8 The anatomical OCT-based IVTS Group Classification System 5 defines VMA as a specific stage of vitreous separation (Table 20.1 , Fig. 20.1). It is defined as a perifoveal separation of the vitreous cortex with continuing VMA within a 3-mm radius of the foveal center, associated with a completely normal retinal morphology. The detached posterior hyaloid may appear on or above the retinal surface. If it is above the retinal surface, the angle between the detached vitreous cortex and the inner retinal surface is acute. VMA is usually asymptomatic and appears as a normal finding on OCT during the natural course of the progression of PVD. Over time, the vitreous usually separates completely from the inner retinal surface as part of the normal physiologic aging process.























Table 20.1 Anatomic optical coherence tomography based classification of vitreomacular adhesion (VMA), vitreomacular traction (VMT), and full-thickness macular hole (FTMH) according to the International Vitreomacular Traction Study Group classification system

Classification


Subclassification


VMA


Size: Focal (≤1500 μm) or broad (> 1500 μm)


Isolated or concurrent


VMT


Size: Focal (≤1500 μm) or broad (> 1500 μm)


Isolated or concurrent


FTMH


Size: small (≤250 μm), medium (>250– ≤400 μm) or large (> 400 μm)


Status of vitreous: With or without VMT


Cause: Primary or secondary


Source: Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology 2013;120(12):2611–2619.

Fig. 20.1 Optical coherence tomography images showing the anatomical classification of vitreomacular adhesion (VMA) (a,b) and vitreomacular traction (VMT) (c,d). (a) Focal VMA. Yellow arrows mark the sites of vitreomacular attachment. The area of attachment is less than 1500 μm (red line and green numbers), and there is no detectable change in contour and morphology of underlying foveal tissue. (b) Broad VMA. Yellow arrows mark the sites of vitreomacular attachment. The area of attachment is > 1500 μm (red line and green numbers), and there is no detectable change in contour and morphology of underlying foveal tissue. (c) Focal VMT. The yellow arrows mark the sites of vitreomacular attachment. The area of attachment is less than 1500 μm (red line and green numbers), and the foveal morphology is abnormal. (d) Broad MT. Yellow arrows mark the sites of vitreomacular attachment. The area of attachment is more than 1500 μm (red line and green numbers), and the foveal morphology is abnormal with associated cystoid macular edema possibly due to the traction on the retina caused by the anomalous vitreous detachment.

Using the anatomical OCT-based classification system, 5 VMA is subclassified by the size of the VMA as measured using the caliper function tool on OCT into (1) focal VMA, where the size of the VMA is ≤1500 μm; or (2) broad VMA, where the size of adhesion measures more than 1500 μm (Table 20.1, Fig. 20.1). The area of VMA is measured roughly parallel to the retinal pigment epithelium, and small regions of dehiscence (<1 mm) between the vitreous and the inner retina that may be present within the zones of a broad VMA are disregarded. When VMA is not associated with any other ocular disease, it is termed isolated VMA. In cases where VMA is associated with other macular abnormalities, such as diabetic macular edema, age-related macular degeneration, or retinal vein occlusion, it is termed concurrent VMA (Table 20.1 , Fig. 20.1). It should be noted that this OCT-based definition of VMA 5 does not take into account the symptoms, as specific visual symptoms may be subjective and may be caused by a separate disease process.



20.2 OCT-Based Classification of Vitreomacular Traction


During an anomalous progression of PVD, 5 ,​ 6 ,​ 7 excessive traction on the macula can result and cause changes in the foveal contour, compromising vision. 9 The anatomical OCT-based IVTS Group Classification System 5 defines VMT as a perifoveal vitreous separation with continuing vitreomacular attachment within a 3-mm radius of the foveal center, associated with an abnormal retinal morphology (Table 20.1 , Fig. 20.1 , Fig. 20.2). An abnormal retinal morphology may involve distortion of the fovea, intraretinal structural changes such as pseudocyst formation (Fig. 20.2), macular schisis, cystoid macular edema (CME), subretinal fluid, elevation of the fovea above the retinal pigment epithelium, or any combination of these. Unlike VMA, where the vitreous separation is virtually always related to a normal physiologic process, VMT is the result of an anomalous progression of PVD.

Fig. 20.2 Optical coherence tomography images showing vitreomacular traction (VMT). (a) Focal VMT with an intraretinal pseudocyst formation. (b) Focal VMT with concomitant occurrence of a secondary disease process, most likely pattern dystrophy. (c) Focal VMT with an associated epiretinal membrane (yellow arrows).

Using the anatomical OCT-based classification system, 5 VMT is subclassified by the size of vitreomacular attachment as measured using the caliper function tool on OCT into (1) focal VMT, where the size of vitreomacular attachment measures ≤ 1500 μm; or (2) broad VMT, where the size of vitreomacular attachment measures > 1500 μm (Table 20.1 , Fig. 20.1). As with VMA, when VMT is not associated with any other ocular disease, it is termed isolated VMT. In cases where VMT is associated with other macular abnormalities, it is termed as concurrent VMT (Table 20.1 , Fig. 20.2).


As PVD progresses, residual cortical vitreous may be left on the retinal surface, even in the setting of a complete, or stage 4, PVD with Weiss ring. This occurrence is termed vitreoschisis. 10 ,​ 11 The residual vitreous remnant may serve as a nidus for proliferation, thus forming an epiretinal membrane (ERM). ERM typically contains glial cells and histiocytes that collect and attach to the vitreous remnant on the retinal surface. 12 Contracture of an ERM may cause further traction on the macula, resulting in distortion of the retinal morphology. Sometimes, VMT and ERM are seen on OCT simultaneously (Fig. 20.2).



20.3 OCT-Based Classification of Full-Thickness Macular Hole


The Gass classification of macular holes is widely used clinically and was based on careful clinical examination; this classification predates both the invention of OCT and the use of vitrectomy to repair macular holes. It divides macular holes into four stages (Table 20.2). 13 ,​ 14 Over the past few years, OCT has increased the understanding of the anatomy and progression of macular holes. The anatomical OCT-based IVTS Group Classification System 5 defines a full-thickness macular hole (FTMH) as an anatomical defect in the fovea that involves an interruption of all the neurosensory retinal layers from the inner limiting membrane (ILM) to the retinal pigment epithelium. This definition requires such a detection on at least one OCT B-scan. Sometimes, small FTMHs are missed by examining only one OCT B-scan, and so, a series of closely spaced OCT B-scans is a more appropriate way to examine for an FTMH on OCT.





























Table 20.2 Comparison of the commonly used clinical stages of macular hole and the anatomical optical coherence tomography (OCT)-based classification of vitreomacular adhesion, vitreomacular traction, and macular hole according to the International Vitreomacular Traction Study Group classification system) 5

Macular hole stages in common clinical use


Anatomic OCT-based classification


Stage 0


VMA


Stage 1: Impending macular hole


VMT


Stage 2: Small hole


Small or medium FTMH with VMT


Stage 3: Large hole


Medium or large FTMH with VMT


Stage 4: FTMH with PVD


Small, medium or large FTMH without VMT


Abbreviations: FTMH, full-thickness macular hole; PVD, posterior vitreous detachment; VMA, vitreomacular adhesion; VMT, vitreomacular traction.


Source: Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology 2013;120(12):2611–2619.


Using the anatomical OCT-based classification system, 5 an FTMH is subclassified based on the following parameters: (1) size of the hole, (2) status of the vitreous, and (3) cause of FTMH.



20.3.1 Size


Using the caliper function tool on OCT, the aperture size of the FTMH is measured roughly parallel to the retinal pigment epithelium at the narrowest opening of the hole in the mid retina or at the photoreceptor tips (Table 20.1 , Fig. 20.3). Using this function, FTMH is classified as small, medium, or large based on its aperture size on OCT. OCT-based measurements of the aperture size of FTMH predict medical and surgical treatment outcomes. 15 ,​ 16 ,​ 17 A small FTMH is defined as a FTMH with an aperture size measuring ≤ 250 μm (Table 20.1, Fig. 20.3). This cutoff is obtained from studies showing that small FTMHs are associated with a small rate of spontaneous closure and a rate of closure approaching 100% with vitrectomy. 16 Small FTMHs are also associated with the best response (approximately 60%) to pharmacologic vitreolysis. 16 A medium FTMH is defined as an FTMH with an aperture size measuring > 250 μm and ≤ 400 μm (Table 20.1 , Fig. 20.3). Postsurgical FTMH closure rates for medium FTMHs approach approximately 90% with complete removal of the residual hyaloid, with or without peeling of the inner limiting membrane. 15 ,​ 17 Compared with small FTMHs, medium FTMHs have a lower response rate (approximately 50%) to pharmacologic vitreolysis. 18 A large FTMH is defined as an FTMH with an aperture size measuring > 400 μm(Table 20.1 , Fig. 20.3). Roughly half the FTMHs are large FTMHs at diagnosis. They have a 90 to 95% closure rate afater vitrectomy with inner limiting membrane peeling and a 75% closure rate after vitrectomy without inner limiting membrane peeling. 19 Pharmacologic vitreolysis has been tried in a few eyes with large FTMHs, but no anatomical success has been reported so far in this group. 16

Fig. 20.3 Optical coherence tomography (OCT) images showing the anatomical classification of full-thickness macular hole (FTMH), defined anatomically as a full-thickness interruption all the retinal layers from the inner limiting membrane to the retinal pigment epithelium. (a) Small FTMH ( ≤ 250 μm) associated with vitreomacular traction (yellow arrow). The aperture size is measured using the OCT caliper function as a line drawn roughly parallel to the retinal pigment epithelium (red line and green numbers) at the narrowest hole width in the mid retina or at the photoreceptor tips. (b) Medium FTMH (> 250 μm ≤ 400 μm) as measured using the OCT caliper function (red line and green numbers). (c) Large FTMH (> 400 μm) as measured using the OCT caliper function (red line and green numbers).

Only gold members can continue reading. Log In or Register to continue

Jun 13, 2020 | Posted by in OPHTHALMOLOGY | Comments Off on 20 Vitreomacular Traction and Optical Coherence Tomography Classification
Premium Wordpress Themes by UFO Themes