Ultrastructural correlation of spectral-domain optical coherence tomographic findings in vitreomacular traction syndrome

Abstract

Purpose: To examine the ultrastructural correlates of spectral-domain optical coherence tomography (SD-OCT) findings in patients with vitreomacular traction (VMT).

Design: Observational case series.

Methods: Retrospective analysis of six eyes of consecutive patients who underwent vitrectomy surgery for VMT was performed in this single-center, noncomparative study. One patient had a concurrent macular hole. Preoperative assessment included SD-OCT examination with 3-dimensional image reconstruction. During surgery the vitreous cone was dissected from the vitreous body using scissors, then removed from the surface of the retina with a combination of sharp dissection and peeling, and subsequently submitted for histologic and transmission electron microscopic processing.

Results: SD-OCT showed prominent vitreal-foveal adhesion in all six eyes. Each eye had an epiretinal membrane (ERM) under the detached perifoveal posterior vitreous detachment. In all eyes this ERM appeared to course up the cone of attached vitreous and along the back surface of the posterior vitreous face. Ultrastructural analysis showed fibrocellular proliferations in the vitreous specimens in all six cases, which included retinal pigment epithelium (RPE) cells (five eyes), fibrocytes (four eyes), and macrophages (three eyes).

Conclusions: The adhesion between the vitreous and fovea in vitreomacular traction syndrome is accompanied by fibrocellular proliferation along the exposed surfaces of the inner retina and the posterior surface of the vitreous. This fibrocellular proliferation may augment the adhesion between the vitreous and fovea, and may account for the prominent OCT signal seen along the posterior surface of the vitreous in these cases.

Figures

FIGURE 1

Patient 6 with vitreomacular traction (VMT) with associated epiretinal membrane (ERM) and macular hole. Preoperative 3-dimensional (3D) spectral-domain optical coherence tomography (SD-OCT) shows cone-shaped vitreoretinal adhesion (arrow, Top left) and a prominent ERM on retinal surface (Top right) with apparent continuation of this proliferation on the detached posterior hyaloid face (Top right and Bottom left). Note the clear distinction between the hyperreflective proliferation and the adjacent normal posterior hyaloid face. The proliferation on the posterior hyaloid was clearly visible intraoperatively (Bottom right). Arrowheads in Top right, Bottom left, and Bottom right panels mark identical location on the proliferation on the posterior vitreous.

FIGURE 2

Ultrastructural analysis of ERM in vitreous cone of Patient 6 with vitreous (10 to 12 nm) collagen (asterisk), which is sandwiched between retinal pigment epithelium (RPE) with surface mircovilli (arrowheads) and internal limiting membrane (ILM, Top). Higher magnification of RPE cells shows microvillous processes (arrowheads) forming tubuloacinar structures with lumens (x) and overlying posterior hyaloid 10- to 12-nanometer collagen fibrils (asterisk).

FIGURE 3

Ultrastructural analysis of the specimen from Patient 4 with VMT. Transmission electron microscopy (TEM) of the membrane on the posterior vitreous with RPE cell forming acinar structures with lumens (x), vitreous collagen fibrils (asterisk), and a macrophage [M] (arrow).

FIGURE 4

TEM analysis of fibrocellular proliferation in Patient 5 showing an RPE cell (arrows) on collagen fibrils (asterisk) with an overlying M.

FIGURE 5

ERM associated with VMT in Patient 5 consisting of a layer of 10-nm collagen fibrils (between arrowheads), which is interposed between the ILM and a layer of fibrocytes (arrow).

FIGURE 6

SD-OCT and TEM findings in Patient 3 with VMT and ERM. Preoperative SD-OCT shows broad vitreomacular adhesion with retinal distortion and macular detachment (Top left and Top right). Note thickening and hyperreflectivity of the posterior hyaloid face. Skip areas in this hyperreflectivity (arrows, Top right) suggest that this signal represents abnormal fibrocellular proliferation on the posterior vitreous face, since the posterior hyaloid should be intact and continuous. TEM analysis of the surgical specimen from this same patient showed the membrane on the posterior hyaloid containing a fibrocyte (arrow) with abundant intracytoplasmic rough endoplasmic reticulum and cortical vitreous collagen fibrils (asterisk, Bottom left) and RPE cell with surface microvillus processes (arrowhead) and collagen fibrils (asterisk, Bottom right). Material between collagen fibrils and cellular elements likely represents extracellular matrix elaborated by neighboring cells.

FIGURE 7

Proposed mechanism of ERM proliferation in VMT syndrome. After partial posterior vitreous detachment with persistent vitreofoveal attachment, vitreous collagen remaining on the retina acts as a scaffolding for ERM formation (arrows). Fibrocellular proliferation continues past the vitreo-retinal interface onto the detached posterior hyaloid face (large arrow).