Optical Coherence Tomography-Based Quantification of Photoreceptor Injury and Recovery in Vogt-Koyanagi-Harada Uveitis

Single Cell RNA Sequencing Analysis of Mouse Retina Identifies a Subpopulation of Muller Glia Involved in Retinal Recovery From Injury in the FCD-LIRD Model

Purpose

Although retinal light injury models have been useful in understanding aspects of retinal degeneration and retinal oxidative stress, information on retinal recovery from oxidative/photoinflammatory retinal injury is scarce. The fundus camera-delivered light-induced retinal degeneration model is a simple and reproducible retinal light injury model developed to recapitulate not only the retinal degeneration aspect, but also the retinal recovery from injury. In this study, we used the fundus camera-delivered light-induced retinal degeneration model to perform cell type-specific analyses of the acute and subacute retinal responses to light injury.

Methods

C57BL/6J eyes were collected before or after light injury (4 hours, 48 hours, and day 5). Retina samples were processed into single-cell suspensions. Droplet-based encapsulation of single cells was performed to generate libraries for sequencing.

Results

Gene expression analysis generated 23 clusters encompassing all known major retinal cell populations. Using unbiased analyses, we identified genes and pathways that were significantly altered in each cell type after light injury, including some cellular processes suggestive of activation of pathways for retinal recovery (e.g., synaptogenesis signaling, ephrin receptor signaling, and Reelin signaling in neurons). More importantly, our data show that a subpopulation of Muller glia cells may play an important role in the cellular recovery process.

Conclusions

This work identifies acute and subacute cell type-specific responses to retinal photo-oxidative injury. A subpopulation of Muller glia seems to initiate the cellular recovery process. A better understanding of these responses may be helpful in identifying therapeutic approaches to minimize retinal damage and maximize recovery after exposure to injury.

Retinal Pigment Epithelial Characteristics in Acute and Resolved Vogt-Koyanagi-Harada Disease

Vogt-Koyanagi-Harada (VKH) disease is an auto-immune inflammatory disease of choroidal origin. During the acute stage, optical coherence tomography (OCT), however, may not be able to assess the entire choroid. The aims of the paper were to evaluate the role of retinal pigment epithelium (RPE) as a biomarker of inflammation in acute VKH. This was a retrospective observational study done in 55 eyes of 29 patients with acute VKH. RPE thickness, total choroidal thickness, and RPE reflectivity before and after resolution were analyzed using image J software. Correlations between several baseline and post-resolution parameters were performed, and factors affecting change in visual acuity were analyzed. A significant decrease in RPE thickness and a significant increase in RPE reflectivity were seen following resolution of the disease. Furthermore, there was a significant correlation between RPE and choroidal thickness during the acute stage of the disease. Baseline visual acuity and the presence of bacillary detachment at baseline were the only factors responsible for changes in visual acuity. We propose the utility of RPE layer as a surrogate biomarker of choroidal activity and inflammation in terms of RPE reflectivity and RPE thickness during the acute stage of VKH, especially when there is poor imaging of the choroid.

Bilateral Complete Loss and Partial Regeneration of Photoreceptor Layers in a Pediatric Vogt-Koyanagi-Harada (VKH) Case

Vogt-Koyanagi-Harada (VKH) disease is a multisystem autoimmune disease affecting melanocyte-containing tissues in the eyes, meninges, ear, and skin. As far as we are aware, this is a unique case report documenting the regeneration of the photoreceptor layer after bilateral complete loss of the photoreceptor layer in a child with VKH. We report a case of a 12-year-old male with no significant past medical history who presented during the chronic stage of incomplete VKH. He was found to have a complete loss of photoreceptor layer in both eyes during a work-up to confirm the aforementioned disease. Upon receiving his first pulse dose of 500 mg IV methylprednisolone as a treatment course, he developed severe steroid-induced hyperglycemia (random blood glucose of 17.6 mmol/L). Additionally, a brain MRI revealed pituitary gland changes compatible with diabetes insipidus, which is a combination that was mentioned once in the literature before. A review of the systems did not suggest any other systemic diseases. The patient's elevated blood sugar level was managed by a pediatrician, and it normalized. At his last visit, optical coherence tomography (OCT) showed hypertrophy/regeneration of the photoreceptor layer. This case report indicates that retinal photoreceptor layer regeneration can be sometimes observed with follow-up after the resolution of inflammation and uveitis.

BACILLARY LAYER DETACHMENT: MULTIMODAL IMAGING AND HISTOLOGIC EVIDENCE OF A NOVEL OPTICAL COHERENCE TOMOGRAPHY TERMINOLOGY: Literature Review and Proposed Theory

PURPOSE

To clarify the histologic basis of bacillary layer detachment (BALAD) through a review of the current literature and an analysis of retinal imaging.

METHODS

The literature for previous reports of BALAD were reviewed. An analysis of retinal images was performed to support anatomical conclusions.

RESULTS

A total of 164 unique patients with BALAD on optical coherence tomography (OCT) were identified from the published literature. Twenty-two underlying etiologies, all associated with subretinal exudation, were identified. Forty-one different OCT terminologies were found. The defining OCT feature of BALAD was a split at the level of the photoreceptor inner segment myoid creating a distinctive intraretinal cavity. Resolution of BALAD was followed by a rapid restoration of the ellipsoid zone. Histology of age-related macular degeneration eyes suggests that individual photoreceptors can shed inner segments. Furthermore, detachment of the entire layer of inner segments is a common postmortem artifact. It is proposed that BALAD occurs when outwardly directed forces promoting attachment of photoreceptor outer segments to the retinal pigment epithelium exceed the tensile strength of the photoreceptor inner segment myoid.

CONCLUSION

This review serves to strengthen the OCT nomenclature "bacillary layer detachment," based on specific reflectance information obtained by OCT and previously published histologic observations.

[Autofluorescence combined with spectral domain optical coherence tomography for diagnosis and follow-up of acute Vogt-Koyanagi-Harada disease]

OBJECTIVE

To evaluate the value of fundus autofluorescence (FAF) imaging combined with spectral domain optical coherence tomography (SD-OCT) in diagnosis, prognostic assessment and follow-up observation of acute Vogt-KoyanagiHarada (VKH) disease.

METHODS

Clinical data were collected from 12 patients (23 eyes) with acute VKH disease treated in our hospital from May, 2018 to November, 2019, including detailed medical history, best corrected visual acuity (BCVA), and results of slit lamp biomicroscopy, fundus photography, SD-OCT, fundus fluorescein angiography (FFA) and FAF imaging.SDOCT and FAF imaging were repeated after a course of treatment and in follow-up examination, and the results were compared with those at the time of admission.

RESULTS

VKH disease involved both eyes in 11 patients (91.7%).Fundus photography showed optic disc edema in 16 eyes (69.6%), and multiple retinal neuroepithelial detachment was detected by SD-OCT in all the involved eyes (100%).IN all the eyes, FFA revealed small and dense fluorescein leakage in the early stage and fluorescein accumulation in advanced stages of VHK disease to form multiple dye pooling in the areas of serous detachment.Hyperauto fluorescence was a common finding in FAF imaging (100%), and the area involved was consistent with that of fluorescein accumulation shown by FAF imaging.Ten eyes (43.5%) showed patches of relative hypoautofluorescence in the hyperauto fl uorescence areas, and granular hyperauto fl uorescence was found in the lesions in 4 eyes (17.4%).During the remission period of VKH disease, FAF imaging showed normal finding in 8 eyes (34.8%) and reduced areas (by 55.2%) and intensity (by 46.5%) of hyperautofluorescence in 9 eyes (39.1%).In 6 eyes (26.1%), only a few hyperautofluorescent spots scattered in the macula were observed.SD-OCT demonstrated significantly reduced (by 69.5% on average) or even disappearance of subretinal fluid in the eyes.The fluorescence intensity in FAF imaging showed a significant positive correlation with the volume of subretinal fluid detected by SD-OCT (r=0.626, P < 0.05).

CONCLUSIONS

The combination of fluorescein angiography, FAF imaging and SD-OCT can significantly improve the diagnostic accuracy of VKH disease.FAF imaging combined with SD-OCT provides an effective and noninvasive modality for evaluation of remission and monitoring the changes in VKH disease.

Assessment of macular capillary perfusion in patients with inactive Vogt-Koyanagi-Harada disease: an optical coherence tomography angiography study

PURPOSE

To assess macular capillary perfusion in patients with inactive Vogt-Koyanagi-Harada (VKH) disease by using optical coherence tomography angiography (OCTA).

METHODS

A total of 51 eyes of 51 patients with inactive VKH (group 1, n = 23) and healthy volunteers (group 2, n = 28) underwent detailed eye examination including OCTA (RTVue-XR Avanti) scanning. OCTA images (6 × 6 mm) were assessed for central retinal thickness (CRT), subfoveal choroidal thickness (SFCT), vessel densities (VD) in superficial capillary plexus (SCP) and deep capillary plexus (DCP), choriocapillaris (CC) flow area and vessel flow density (VFD), foveal avascular zone (FAZ) area and acircularity index (AI).

RESULTS

The mean ages of group 1 (13 female, 10 male) and group 2 (15 female, 13 male) were 39.9 ± 11.8 (range, 24-58) and 38.9 ± 8.5 (range, 29-51) years, respectively (p = 0.773). CRT and SFCT were 218.2 ± 39.4 μm and 195.6 ± 28.6 μm in group 1, while 243.5 ± 9.7 μm and 316.7 ± 20.1 μm in group 2, respectively (p < 0.05). VD in SCP and DCP were significantly lower in group 1 (50.6 ± 4.7% vs. 54.3 ± 3.4% and 53.9 ± 3.6% vs. 61.1 ± 2.7% respectively; p < 0.05). FAZ areas were 0.32 ± 0.11 mm² in group 1 and 0.25 ± 0.06 mm² in group 2 (p = 0.046). There was no statistically significant difference between groups regarding AI, CC flow area, and VFD (p > 0.05). There was weak negative correlation between BCVA (logMAR) and parafoveal and perifoveal VD in SCP and DCP of group 1 (p < 0.05).

CONCLUSION

Macular capillary perfusion was significantly reduced both in SCP and DCP in patients with inactive VKH disease.

En Face Optical Coherence Tomography Imaging Ellipsoid Zone Regeneration in Laser-Induced and Solar Maculopathies

The purpose of the study was to analyze imaging findings in spectral domain en face optical coherence tomography (SD OCT) in patients with laser-induced and solar maculopathies focusing on the possible regeneration of the ellipsoid zone. In a retrospective case series of 3 patients (4 eyes) with solar maculopathy and 2 patients (3 eyes) with laser-induced maculopathy who underwent a comprehensive ocular examination, ellipsoid zone (EZ) was segmented from SD OCT data. Evaluation of EZ in en face OCT revealed a hyporeflective lesion surrounded by a hyperreflective border. The area of EZ alteration was measured manually in en face OCT. All patients showed partial EZ regeneration. Mean EZ alteration decreased from 0.12 mm² (range: 0.05-0.32) at baseline to 0.07 mm² (range: 0.01-0.22) at last follow-up (p = 0.018, mean follow-up: 372 days; range: 115-592). Mean best visual acuity (BVA) improved from 20/36 at baseline to 20/30 (p = 0.018). In conclusion, en face OCT imaging clearly delineated the area of EZ alteration in patients with laser-induced and solar maculopathies. Follow-up showed significant reformation of the EZ as well as improvement of BVA.

Normal Variation of Photoreceptor Outer Segment Volume With Age, Gender, Refractive Error, and Vitreomacular Adhesion

BACKGROUND AND OBJECTIVE

Thickness and volume changes of the photoreceptor outer segment (PROS) layer on spectral-domain optical coherence tomography (SD-OCT) images are associated with various disease states. However, there are limited data on normal anatomical variation. This study evaluates the correlation of PROS volume with age, gender, refractive error, and presence of vitreomacular adhesion (VMA) in healthy subjects.

PATIENTS AND METHODS

SD-OCT scans of 68 normal eyes were analyzed. The ellipsoid zone and the apical retinal pigment epithelium boundary were segmented using an automated algorithm. The PROS volume was calculated as the region bounded by these two layers within a 6-mm diameter circle centered at the fovea. A general linear model was used for statistical analysis.

RESULTS

PROS volume increased with age to a significant degree (P = .013). Gender, refractive error, and presence of VMA were insignificant factors.

CONCLUSION

PROS volume, as measured on routine SD-OCT, increases with age in healthy subjects, after adjusting for gender, refractive error, and VMA. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:523-527.].

Recovery of macular cone photoreceptors in Vogt-Koyanagi-Harada disease

PURPOSE

Our purpose was to study changes in macular cone photoreceptors in Vogt-Koyanagi-Harada (VKH) disease patients after high-dose corticosteroid treatment using an adaptive optics (AO) fundus camera.

METHODS

We retrospectively analyzed 16 eyes of eight patients with new-onset acute VKH disease that were studied retrospectively. After serous retinal detachment (SRD) had resolved, AO images were obtained using the rtx1™ AO fundus camera over a 12-month course. Cone counting was performed in the nasal, temporal, superior and inferior areas of the macula 0.75 mm from the foveal center. A control group of 30 eyes of 30 healthy subjects was established for comparison.

RESULTS

In the eyes with VKH disease, the mean cone densities 0.75 mm from the foveal center were 11,847 at baseline (resolution of SRD), and 15,218, 16,684 and 17,686 cones/mm², at 3, 6, and 12 months later, respectively. The mean cone densities at 3, 6, and 12 months were significantly increased compared to those of baseline (p = 0.007, p < 0.001, and p < 0.001, respectively); however, they were significantly lower than that of the healthy control eyes (p < 0.001). The mean cone densities at areas with a previous presence of cystoid spaces were significantly lower than those without cystoid spaces at the baseline, and at 3, 6, and 12 months (p < 0.001, p = 0.007, p < 0.001, and p = 0.008, respectively).

CONCLUSIONS

Cone densities were gradually increased after the resolution of SRD in the eyes of VKH disease patients. The presence of cystoid spaces might be a marker of severe damage to cone photoreceptors.

Photoreceptor Cell Injury Starts in the Initial Stage of Vogt-Koyanagi-Harada Disease

PURPOSE

To demonstrate photoreceptor cell injury in Vogt-Koyanagi-Harada (VKH) disease.

METHODS

The SD-OCT and FAF tests of 16 patients diagnosed with VKH disease that was followed up from the initial stage to the convalescent stage were reviewed.

RESULTS

In the initial stage of VKH disease, there was hyperautofluerescence around the macular edema. In the convalescent stage of VKH disease, loss of photoreceptor and injury of RPE have been detected by OCT scan at the same area, which was corresponded with the abnormalities in FAF.

CONCLUSIONS

The VKH disease causes photoreceptor injury starting in the initial stage of the disease.