Session Title: Imaging I
Session Date/Time: Friday 18/09/2015 | 08:00-09:30
Paper Time: 09:12
First Author: : A.Matet SWITZERLAND
Co Author(s): : M. Savastano M. Rispoli C. Bergin P. Crisanti F. BeharCohen B. Lumbroso
PURPOSE:To characterize perifoveal intraretinal cavities observed around full-thickness macular holes using en face optical coherence tomography (OCT) and to establish correlations with histology of human and primate maculae, with an emphasis on the previously described Z-shaped morphology of Müller cells.
Retrospective non-consecutive observational case series, and animal histological supportive evidence.
Macular en face OCT scans (on the Spectralis and RTVue-100 devices) of eight patients with full-thickness macular hole were analyzed to detect and quantify the areas of hypo reflective spaces in the frontal plane, using an automated method developped on the Image J software. The quantitative and qualitative assessments of these images were then compared with macular flat-mounts and sections from one normal human donor eye and two normal primate eyes (Macaca fascicularis). Immunohistochemistry was used to study the distribution of glutamine synthetase, a marker of Müller cells, and zonula occludens-1, a tight-junction protein.
The mean area of the hypo reflective cystoid spaces around full-thickness macular holes on en face OCT was lower in the inner nuclear layer (INL) than in the complex formed by the outer plexiform (OPL) and the Henle fiber layers (HFL): 5.0×10-3 versus 15.9×10-3 mm2, respectively (P: 0.0001, Kruskal Wallis test). In the OPL and HFL, cavities were radially elongated with a stellate pattern, whereas in the INL they were rounded and formed vertical tubular structures that could be followed along consecutive sections within a stack. Immunohistochemistry of the human and primate maculae confirmed that Müller cells followed a radial distribution around the fovea in the frontal plane, and a “Z-shaped” course in the axial plane, running obliquely in the OPL and HFL, and vertically in the inner layers. In addition, zonula occludens-1 co-localized with Müller cells within the complex of OPL and HFL, indicating possible junctions between Müller cells and cone axons.
The dual profile of cavities identified around full-thickness macular holes correlates with Müller cell morphology. In addition, this pattern is consistent with the pathophysiology hypothesis of intra- or extracellular fluid accumulation along these perifoveal cells, as observed around macular holes. The observation of tight-junctions proteins along the course of Müller cells and cone axons in the perifoveal region also illustrates a possible mechanism of tissue dissociation, that may occur along the course of Müller cells, as exemplified here in the case of full-thickness macular holes.