Abstract
Purpose: :
The pathogenesis of lamellar macular holes is still debated. Surgical observations, made during lamellar hole treatment, have lead to notice a particular yellow and fluffly epiretinal tissue (ERT) which can be peeled on top of the internal limiting membrane (ILM). The aim of the study was to analyze the ERT found and peeled in lamellar holes surgery.
Methods: :
Ten eyes were diagnosed as having lamellar hole with Spectral-Domain optical coherence tomography (SD-OCT) (Heidelberg Engineering, Heidelberg, Germany) and were operated with pars plana vitrectomy, ERT peeling, ILM peeling and air tamponade. The ERT and the ILM were collected and fixated with a mixture of Paraformaldehyde 2% plus Glutaraldehyde 0,1%. The specimens were prepared for light microscopy and immuno-section. Immunocytochemical studies were performed using markers for glial fibrillic acidic protein (GFAP), αSmooth muscle actin (αSMA), cellular retinaldehyde binding protein (CRALBP) which stains the glial and retinal pigment epithelial cells, Neurofilament (NF) to stain retinal ganglion cells, CD68 to stain macrophages and collagen type II to search for native vitreous collagen. Ultrathin sections were selected, following light microscopy, for morphological analysis with Transmission Electron Microscopy (TEM).
Results: :
SD-OCT showed an intraretinal splitting, with decreased foveal thickness, and the presence of two distinct ERT: Type D was a dense, hyporeflectant tissue, with no aspect of tangential or antero-posterior traction; Type T resembled a thin epiretinal membrane with tangential traction. TEM allowed to find dense vitreous strands surrounded by a darker line of even more densely packed vitreous band and cell proliferation. Immunocytochemical staining confirmed cellular proliferation, mainly positive for GFAP, SMA and collagen type II.
Conclusions: :
Lamellar holes are associated with epiretinal tissue mainly comprised of glial cells and native vitreous collagen, the origin of which still needs to be well defined. The implications of these findings on the pathogenesis of lamellar hole call for further study.
Keywords: macular holes • immunohistochemistry