Abstract
Purpose :
Hyalocyte-like cells (HLC), also known as macrophage-like cells, are cells located at the vitreoretinal interface. Recently, HLCs have been imaged in human subjects by averaging several acquisitions of optical coherence tomography (OCT) volumes. In this study, we investigated whether multiple acquisition averaging of OCT volumes could visualize HLCs in patients with epiretinal membranes (ERM).
Methods :
Five patients with ERM and three control subjects were recruited for the study. OCT angiography (OCTA) and OCT volumes were simultaneously acquired using the RTVue XR Avanti (Optovue, USA). For each eye, we performed 3x3 mm2 scans at two locations: (1) ~7 degrees temporal to the fovea and (2) ~7 degrees nasal to the fovea. At each location, ten scans were serially acquired for averaging. Rigid followed by non-rigid of the volumes was performed using MATLAB (MathWorks, USA). The B-scans of were then cross-correlated and averaged. OCT volumes were then inspected in ImageJ. A projection of a 3 um slab above the inner limiting membrane (ILM) was used to isolate the HLCs from the underlying retina. Cell counting was performed manually.
Results :
Fig. 1A shows a composite image from a control subject’s left eye. En face OCTA is shown in red, while the projection of the 3 um slab above the ILM is shown in green. HLC’s were numerously observed with a star-shaped appearance and regular spacing (Fig.1B). Fig. 2A shows a composite image from a the right eye of a subject with ERM. The shape of HLCs in ERM eyes appeared more elongated, stretched, and spindle-shaped compared to controls (yellow arrows, Fig. 2B). Additionally, HLCs were far less abundant than in controls (1.92 +/- 1.9 cells/mm2 vs. 50.5 +/- 22 cells/mm2) and irregularly spaced.
Conclusions :
Using serial acquisition, image registration, and averaging of OCTA and OCT volumes, we observed HLCs on the surface of ERMs. HLCs were less numerous in patients with ERM than controls and possessed a more elongated, spindle-shaped appearance. Imaging of HLCs with OCT could potentially provide biomarkers for the management of ERMs.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.