Speaker
Description
Hyalocytes are macrophage-lineage border immune cells located at the posterior hyaloid and vitreoretinal interface (VRI), a specialised compartment between the vitreous and neural retina. Clinical OCT frequently reveals punctate hyperreflective cell-like signals at this interface, but their cellular identity remains uncertain. These signals are often grouped under broad descriptive terms such as macrophage-like cells or microglia-like cells, although label-free OCT alone cannot assign molecular identity.
This project combines in vivo retinal imaging with ex vivo spatial phenotyping to improve the detection, localisation and interpretation of VRI-associated cell-like signals in health and inflammation. In human participants, swept-source OCT/OCTA was used for same-location imaging of hyperreflective VRI signals. Thin en face structural OCT slabs positioned around the inner limiting membrane and posterior hyaloid were registered to OCTA vascular landmarks to improve spatial localisation and longitudinal comparability. In healthy eyes, VRI-associated objects showed a reproducible parafoveal distribution with relative sparing of the foveal avascular zone. In uveitic eyes, these signals showed focal clustering around inflammatory lesions and increased apparent object area, suggesting inflammation-associated remodelling of the VRI compartment.
Adaptive optics scanning light ophthalmoscopy provided complementary cellular-resolution imaging of VRI-associated structures in living eyes, allowing assessment of morphology and spatial relationships to retinal vasculature. To support cellular interpretation, human donor retinal tissue was analysed using multiplex immunofluorescence. VRI-localised IBA1-positive cells with round-to-amoeboid morphology and enriched CD74 expression were identified at the retinal surface, distinct from ramified parenchymal microglia within deeper retinal layers.
Together, these findings support a translational imaging framework in which SS-OCT provides scalable object-level mapping, AOSLO provides single-cell morphological information, and ex vivo immunofluorescence provides molecular and anatomical validation. This approach may help refine the interpretation of VRI hyperreflective cell-like signals and improve the use of advanced retinal imaging as a window onto immune activity at the retina–vitreous boundary.
Lay Abstract
The retina contains immune cells that help maintain tissue health and respond to inflammation. Some of these cells sit at the boundary between the vitreous gel and the retina, known as the vitreoretinal interface. One important cell type in this region is the hyalocyte, a macrophage-lineage immune cell. However, in routine clinical eye scans, these cells are difficult to identify with certainty.
In this project, I use advanced retinal imaging to study small bright cell-like signals seen near the retinal surface on OCT scans. These signals are often broadly described as macrophage-like or microglia-like cells, but their true identity is not always clear. By combining swept-source OCT, OCT angiography, and adaptive optics imaging, we can better locate these signals and study their size, shape, distribution, and relationship to retinal blood vessels in living eyes.
To support the imaging findings, I also use human retinal tissue and multiplex immunofluorescence to examine immune cell markers directly. This helps test whether some OCT-visible signals are consistent with hyalocyte-like cells rather than retinal microglia.
This work may improve how we interpret retinal imaging signals in health and inflammatory eye disease such as uveitis.
| Lay Title | Seeing retinal immune cells at the retina–vitreous boundary |
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| Role | PhD Student |