OCT and Fundus Autofluorescence Enhances Visualization of White Dot Syndromes

Fundus Autofluorescence in Posterior and Panuveitis-An Under-Estimated Imaging Technique: A Review and Case Series

Fundus autofluorescence (FAF) is a prompt and non-invasive imaging modality helpful in detecting pathological abnormalities within the retina and the choroid. This narrative review and case series provides an overview on the current application of FAF in posterior and panuveitis. The literature was reviewed for articles on lesion characteristics on FAF of specific posterior and panuveitis entities as well as benefits and limitations of FAF for diagnosing and monitoring disease. FAF characteristics are described for non-infectious and infectious uveitis forms as well as masquerade syndromes. Dependent on the uveitis entity, FAF is of diagnostic value in detecting disease and following the clinical course. Currently available FAF modalities which differ in excitation wavelengths can provide different pathological insights depending on disease entity and activity. Further studies on the comparison of FAF modalities and their individual value for uveitis diagnosis and monitoring are warranted.

Persistent Placoid Maculopathy: Lichen-like Lesions Growing between Retinal Pigment Epithelium and Bruch's Membrane

PURPOSE

To report the novel imaging findings in persistent placoid maculopathy (PPM) from the first case series of Asian subjects.

DESIGN

Retrospective observational case series.

SUBJECTS

Patients with PPM from 2013 to 2023.

METHODS

Medical records and multimodal images from each visit were analyzed.

MAIN OUTCOME MEASURES

Imaging and follow-up findings.

RESULTS

Twenty-one eyes of 16 patients were included. Mean age was 61 (range, 48-84) years old. Five patients showed bilateral involvement. Persistent placoid maculopathy lesions were unremarkable on color fundus photography, autofluorescence, and fluorescein angiography. Hypofluorescent spots with a lichen-like appearance presented in all phases of indocyanine green angiography, which were most prominent in the late phase and presented in a fused (71%) or clustered (29%) pattern. The hypofluorescence correlated with the lesions between the retinal pigment epithelium (RPE) and Bruch's membrane (BM) with moderate reflectivity on OCT, and the thickness ranged from slit-like to mound-like. The intensity of hypofluorescence sometimes varied in the same eye and correlated with the thickness of sub-RPE lesions on OCT. No abnormal blood flow signals were detected in either the sub-RPE space or choriocapillaris slab of OCT angiography across the PPM lesions. Peripapillary (5 eyes, 24%) and extra posterior pole (2 eyes, 10%) involvements were seen, the former sparing the β zones of optic discs. Ten eyes of 7 patients were followed up (median, 26 months; range, 2-121 months). During follow-up, the lichen-like lesions spread and migrated slowly without changing the plane patterns of the first visit and were limited to sub-RPE growth. The fused lichen-like pattern sprawled around the enlarged base. The clustered lichen-like pattern gradually loosened. Ten eyes (48%, 9 eyes in the fused pattern, 1 eye in the clustered pattern) had secondary choroidal neovascularization (CNV) at the first visit, with type I (6 eyes, 5 of which were polypoidal choroidal vasculopathy) and type II (4 eyes). No new CNV developed during follow-up.

CONCLUSION

Persistent placoid maculopathy lesions were located in the sub-RPE space, as determined by multimodal imaging. Spreading and migration between the RPE and BM may account for their unique lichen-like appearance and progression pattern.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

cGMP-grade human iPSC-derived retinal photoreceptor precursor cells rescue cone photoreceptor damage in non-human primates

Background

Retinal regenerative therapies hold great promise for the treatment of inherited retinal degenerations (IRDs). Studies in preclinical lower mammal models of IRDs have suggested visual improvement following retinal photoreceptor precursors transplantation, but there is limited evidence on the ability of these transplants to rescue retinal damage in higher mammals. The purpose of this study was to evaluate the therapeutic potential of photoreceptor precursors derived from clinically compliant induced pluripotent stem cells (iPSCs).

Methods

Photoreceptor precursors were sub-retinally transplanted into non-human primates (Macaca fascicularis). The cells were transplanted both in naïve and cobalt chloride-induced retinal degeneration models who had been receiving systemic immunosuppression for one week prior to the procedure. Optical coherence tomography, fundus autofluorescence imaging, electroretinography, ex vivo histology and immunofluorescence staining were used to evaluate retinal structure, function and survival of transplanted cells.

Results

There were no adverse effects of iPSC-derived photoreceptor precursors on retinal structure or function in naïve NHP models, indicating good biocompatibility. In addition, photoreceptor precursors injected into cobalt chloride-induced retinal degeneration NHP models demonstrated an ability both to survive and to mature into cone photoreceptors at 3 months post-transplant. Optical coherence tomography showed restoration of retinal ellipsoid zone post-transplantation.

Conclusions

These findings demonstrate the safety and therapeutic potential of clinically compliant iPSC-derived photoreceptor precursors as a cell replacement source for future clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02539-8.

Advances in Retinal Optical Imaging

Retinal imaging has undergone a revolution in the past 50 years to allow for better understanding of the eye in health and disease. Significant improvements have occurred both in hardware such as lasers and optics in addition to software image analysis. Optical imaging modalities include optical coherence tomography (OCT), OCT angiography (OCTA), photoacoustic microscopy (PAM), scanning laser ophthalmoscopy (SLO), adaptive optics (AO), fundus autofluorescence (FAF), and molecular imaging (MI). These imaging modalities have enabled improved visualization of retinal pathophysiology and have had a substantial impact on basic and translational medical research. These improvements in technology have translated into early disease detection, more accurate diagnosis, and improved management of numerous chorioretinal diseases. This article summarizes recent advances and applications of retinal optical imaging techniques, discusses current clinical challenges, and predicts future directions in retinal optical imaging.

Multi-modal imaging and anatomic classification of the white dot syndromes

The white dot syndromes (WDS) are a diverse group of posterior uveitidies that share similar clinical findings but are unique from one another. Multimodal imaging has allowed us to better understand the morphology, the activity and age of lesions, and whether there is CNV associated with these different ocular pathologies. The “white dot syndromes” and their uveitic masqueraders can now be anatomically categorized based on lesion localization. The categories include local uveitic syndromes with choroidal pathology, systemic uveitic syndromes with choroidal pathology, and multifocal choroiditis with outer retinal/choriocapillaris pathology with uveitis and without uveitis. Neoplastic and infectious etiologies are also discussed given their ability to masquerade as WDS.