Imaging of Macrophage-Like Cells in Living Human Retina Using Clinical OCT

PURPOSE. To image retinal macrophages at the vitreoretinal interface in the living human retina using a clinical optical coherence tomography (OCT) device. METHODS. Eighteen healthy controls and three patients with retinopathies were imaged using a clinical spectral-domain OCT. In controls, 10 sequential scans were collected at three different locations: (1) similar to 9 degrees temporal to the fovea, (2) the macula, and (3) the optic nerve head (ONH). Intervisit repeatability was evaluated by imaging the temporal retina twice on the same day and 3 days later. Only 10 scans at the temporal retina were obtained from each patient. A 3-mu m OCT reflectance (OCT-R) slab located above the inner limiting membrane (ILM) surface was averaged. RESULTS. In controls, ramified macrophage-like cells with regular spatial separation were visualized in the temporal and ONH OCT-R images; however, cell structures were not resolvable at the macula. Interim changes in cell position suggestive of cell translocation were observed between images collected on the same day and those collected 3 days later. There was considerable variation in cell density and nearest-neighbor distance (NND) across controls. Mean +/- SD cell densities measured at the temporal and ONH were 78 +/- 23 cells/mm(2) and 57 +/- 16 cells/mm(2), respectively. Similarly, mean +/- SD NNDs measured at the temporal and ONH were 74.3 +/- 13.3 mu m and 93.3 +/- 20.0 mu m, respectively. Nonuniform spatial distribution and altered morphology of the cells were identified in patients with retinopathies. CONCLUSIONS. Our findings showed regular spatial separation and ramified morphology of macrophage-like cells on the ILM surface with cell translocation over time in controls. Their distribution and morphology suggest an origin of macrophage-like cells such as microglia or hyalocytes.