Exploring the choroidal vascular labyrinth and its molecular and structural roles in health and disease

The structure and function of the human choroid

In this manuscript, the structure of the human choroid is reviewed with emphasis of the macro- and microscopic anatomy including Bruch's membrane, choriocapillaris, Sattler's and Haller's layer, and the suprachoroid. We here discuss the development of the choroid, as well as the question of choroidal lymphatics, and further the neuronal control of this tissue, as well as the pathologic angiogenesis. Wherever possible, functional aspects of the various structures are included and reviewed.

Global Research Status Regarding Uveitis in the Last Decade

PURPOSE

To provide an overview on global uveitis research in the last decade in terms of countries/regions, organizations, scholars, journals, trending topics, and fundings.

METHODS

This cross-sectional bibliometric analysis yielded 10656 uveitis publications in English for subsequent bibliometric analysis.

RESULTS

In terms of the number of publications, the leading country/region was the USA (3007). The most productive organization was the University College London (420). The most productive research team was Professor Yang's group (146). A higher h-index was noted in University College London (48). Professor Rosenbaum was the first h-index holder (32). Keywords of interest included topics such as biologics, COVID and OCT. Publications by Ocular Immunology and Inflammation (968) ranked the first position.

CONCLUSIONS

The USA is the leading force in uveitis study. Asian countries/regions, such as China (mainland) and India, are exerting a substantial role worldwide. Trendy topics cover COVID-19, OCTA.

Distribution and determinants of choroidal vascularity index in healthy eyes from deep-learning choroidal analysis: a population-based SS-OCT study

AIMS

To quantify the profiles of choroidal vascularity index (CVI) using fully artificial intelligence (AI)-based algorithm applied to swept-source optical coherence tomography (SS-OCT) images and evaluate the determinants of CVI in a population-based study.

METHODS

This cross-sectional study included adults aged ≥35 years residing in the Yuexiu District of Guangzhou, China, a follow-up population-based study. All participants (n=646) underwent comprehensive ophthalmic examinations, including SS-OCT for quantifying choroidal parameters. The CVI and subfoveal choroidal thickness (SFCT) were measured by a novel AI-based system.

RESULTS

A total of 556 participants were included, with a mean age of 56.4±9.9 years and 44.96% women. The average CVI and SFCT of the overall population were 69.7% (95% CI 69.2 to 70.3) and 263.0 µm (95% CI 257.2 to 268.8), respectively. After adjusting for other factors, older age and longer AL were significantly associated with a lower CVI. The CVI decreased by -0.13% (-0.19 to -0.06, p<0.001) with each 1-year increase in age, -2.10% (-3.29 to -0.92, p=0.001) with each 1 mm increase in AL. Furthermore, significantly positive correlation between CVI and SFCT has been observed, with coefficient of 0.059 (0.052 to 0.065, p<0.001).

CONCLUSION

Using new AI-based choroidal segmentation software, we provided a fast, reliable and objective CVI profile for large-scale samples. Older age and longer AL were independent correlates of choroidal thinning and CVI decline. These factors should be considered when interpreting SS-OCT-based choroidal measurements.

SNORD45A Affects Content of HIF-1α and Promotes Endothelial Angiogenic Function

To find out the differentially expressed small nucleolar RNAs (snoRNAs) in corneal neovascularization and their effect on angiogenesis. The rat model of corneal neovascularization induced by alkali burn was established, and the differentially expressed snoRNAs were sifted by high-throughput sequencing. Human genome homologs were screened and verified in cytopathological models. Polymerase chain reactions (PCRs) and Western blot assays were applied to detect mRNA and corresponding proteins affected by the differentially expressed snoRNA. In vitro, experiments were promoted to identify whether snoRNA affects endothelial cell migration and angiogenesis. Forty-seven differentially expressed snoRNAs were sifted from transparent cornea and neovascularization. According to sequencing and cytopathological model results, SNORD45A was selected for subsequent experiments. At mRNA and protein levels, SNORD45A affected the expression of HIF-1α. SNORD45A promoted endothelial angiogenesis through endothelial cell migration and tube formation regulation. The research suggested that SNORD45A partakes in the corneal neovascularization formation and can become one of the targets for corneal neovascularization therapy.

Bruch's Membrane Calcification in Pseudoxanthoma Elasticum: Comparing Histopathology and Clinical Imaging

Purpose

To investigate the histology of Bruch's membrane (BM) calcification in pseudoxanthoma elasticum (PXE) and correlate this to clinical retinal imaging.

Design

Experimental study with clinicopathological correlation.

Subjects and Controls

Six postmortem eyes from 4 PXE patients and 1 comparison eye from an anonymous donor without PXE. One of the eyes had a multimodal clinical image set for comparison.

Methods

Calcification was labeled with OsteSense 680RD, a fluorescent dye specific for hydroxyapatite, and visualized with confocal microscopy. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (SEM-EDX) and time-of-flight secondary ion mass spectrometry (TOF-SIMs) were used to analyze the elemental and ionic composition of different anatomical locations. Findings on cadaver tissues were compared with clinical imaging of 1 PXE patient.

Main Outcome Measures

The characteristics and topographical distribution of hydroxyapatite in BM in eyes with PXE were compared with the clinical manifestations of the disease.

Results

Analyses of whole-mount and sectioned PXE eyes revealed an extensive, confluent OsteoSense labeling in the central and midperipheral BM, transitioning to a speckled labeling in the midperiphery. These areas corresponded to hyperreflective and isoreflective zones on clinical imaging. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy and TOF-SIMs analyses identified these calcifications as hydroxyapatite in BM of PXE eyes. The confluent fluorescent appearance originates from heavily calcified fibrous structures of both the collagen and the elastic layers of BM. Calcification was also detected in an aged comparison eye, but this was markedly different from PXE eyes and presented as small snowflake-like deposits in the posterior pole.

Conclusions

Pseudoxanthoma elasticum eyes show extensive hydroxyapatite deposition in the inner and outer collagenous and elastic BM layers in the macula with a gradual change toward the midperiphery, which seems to correlate with the clinical phenotype. The snowflake-like calcification in BM of an aged comparison eye differed markedly from the extensive calcification in PXE.

Financial Disclosures

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

Adult stem cells in the eye: Identification, characterisation, and therapeutic application in ocular regeneration - A review

Adult stem cells, present in various parts of the human body, are undifferentiated cells that can proliferate and differentiate to replace dying cells within tissues. Stem cells have specifically been identified in the cornea, trabecular meshwork, crystalline lens, iris, ciliary body, retina, choroid, sclera, conjunctiva, eyelid, lacrimal gland, and orbital fat. The identification of ocular stem cells broadens the potential therapeutic strategies for untreatable eye diseases. Currently, stem cell transplantation for corneal and conjunctival diseases remains the most common stem cell-based therapy in ocular clinical management. Lens epithelial stem cells have been applied in the treatment of paediatric cataracts. Several early-phase clinical trials for corneal and retinal regeneration using ocular stem cells are also underway. Extensive preclinical studies using ocular stem cells have been conducted, showing encouraging outcomes. Ocular stem cells currently demonstrate great promise in potential treatments of eye diseases. In this review, we focus on the identification, characterisation, and therapeutic application of adult stem cells in the eye.

Relationship Between Retinal Layer Thickness and Genetic Susceptibility to Age-Related Macular Degeneration in Asian Populations

Purpose

For OCT retinal thickness measurements to be used as a prodromal age-related macular degeneration (AMD) risk marker, the 3-dimensional (3D) topographic variation of the relationship between genetic susceptibility to AMD and retinal thickness needs to be assessed. We aimed to evaluate individual retinal layer thickness changes and topography at the macula that are associated with AMD genetic susceptibility.

Design

Genetic association study.

Participants

A total of 1579 healthy participants (782 Chinese, 353 Malays, and 444 Indians) from the multiethnic Singapore Epidemiology of Eye Diseases study were included.

Methods

Spectral-domain OCT and automatic segmentation of individual retinal layers were performed to produce 10 retinal layer thickness measurements at each ETDRS subfield, producing 3D topographic information. Age-related macular degeneration genetic susceptibility was represented via single nucleotide polymorphisms (SNPs) and aggregated via whole genome (overall) and pathway-specific age-related macular degeneration polygenic risk score (PRSAMD).

Main Outcome Measures

Associations of individual SNPs, overall PRSAMD, and pathway-specific PRSAMD with retinal thickness were analyzed by individual retinal layer and ETDRS subfield.

Results

CFH rs10922109, ARMS2-HTRA1 rs3750846, and LIPC rs2043085 were the top AMD susceptibility SNPs associated with retinal thickness of individual layers (P < 1.67 × 10-3), all at the central subfield. The overall PRSAMD was most associated with thinner L9 (outer segment photoreceptor/retinal pigment epithelium complex) thickness at the central subfield (β = -0.63 μm; P = 5.45 × 10-9). Pathway-specific PRSAMD for the complement cascade (β = -0.53 μm; P = 9.42 × 10-7) and lipoprotein metabolism (β = -0.05 μm; P = 0.0061) were associated with thinner photoreceptor layers (L9 and L7 [photoreceptor inner/outer segments], respectively) at the central subfield. The mean PRSAMD score was larger among Indians compared with that of the Chinese and had the thinnest thickness at the L9 central subfield (β = -1.00 μm; P = 2.91 × 10-7; R2 = 5.5%). Associations at other retinal layers and ETDRS regions were more heterogeneous.

Conclusions

Overall genetic susceptibility to AMD and the aggregate effects of the complement cascade and lipoprotein metabolism pathway are associated most significantly with L7 and L9 photoreceptor thinning at the central macula in healthy individuals. Photoreceptor thinning has potential to be a prodromal AMD risk marker, and topographic variation should be considered.

Financial Disclosures

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

Choriocapillaris flow deficit and the risk of referable diabetic retinopathy: a longitudinal SS-OCTA study

AIMS

To investigate the association between the choriocapillaris flow deficit percentage (CC FD%) and the 1-year incidence of referable diabetic retinopathy (RDR) in participants with type 2 diabetes mellitus (DM).

METHODS

This prospective cohort study included participants with type 2 DM. The DR status was graded based on the ETDRS-7 photography. The CC FD% in the central 1 mm area, inner circle (1.5 mm to 2.5 mm), outer circle (2.5 mm to 5.0 mm) and the entire area in the macular region were measured using swept-source optical coherence tomography angiography (SS-OCTA). Logistic regression analysis was used to examine the association between baseline CC FD% and 1-year incident RDR.

RESULTS

A total of 1222 patients (1222 eyes, mean age: 65.1±7.4 years) with complete baseline and 1-year follow-up data were included. Each 1% increase in baseline CC FD% was significantly associated with a 1.69 times (relative risk 2.69; 95% CI 1.53 to 4.71; p=0.001) higher odds for development of RDR after 1-year follow-up, after adjusting for other confounding factors.

CONCLUSIONS

A greater baseline CC FD% detected by SS-OCTA reliably predicted higher risks of RDR in participants with type 2 DM. Thus, CC FD% may act as a novel biomarker for predicting the onset and progression of DR.

The Association Between Lipid Profile and Subfoveal Choroidal Thickness in Chinese Patients with Proliferative Diabetic Retinopathy Secondary to Type 2 Diabetes

Introduction

Extensive studies have studied the factors associated with subfoveal choroidal thickness (SFCT). However, studies of the association between lipid profile and SFCT in patients with proliferative diabetic retinopathy (PDR) in type 2 diabetes remain limited. Thus, we aimed to investigate the relationship between lipid profile and SFCT in patients with PDR.

Materials and Methods

This was a retrospective cross-sectional study. The included participants were inpatients who underwent vitrectomy for PDR with type 2 diabetes and contralateral eyes of PDR patients meeting the criteria. Multivariate linear regression analysis was used to determine the independent association between lipid profile and SFCT.

Results

A total of 131 participants with PDR were enrolled in the final analysis. The average age of the participants was 55.76 ± 9.88 years, and the average SFCT was 276.10 ± 92.92 μm. Multivariate linear regression model results showed that in the fully adjusted model, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) had a negative association with SFCT (β = -16.51, 95% CI: -29.57, -3.46; P = 0.0148; β = -42.65, 95% CI: -82.60, -2.70; P = 0.0390; β = -17.89, 95% CI: -33.24, -2.54; P = 0.0245, respectively), while triglyceride was not significantly associated with SFCT (β = 5.23, 95% CI: -18.57, 29.02; P = 0.6678). Furthermore, the results of stratified analysis showed that except for triglyceride, the trends of total cholesterol, HDL-C, LDL-C, and SFCT were consistent among different stratifications in participants.

Conclusion

The cholesterol profile had a significant negative association with SFCT in Chinese PDR patients, but triglyceride was not significantly associated with SFCT. This suggests that these systemic imbalances contribute to choroidal changes, and often coexist in diabetic patients.

Generation of a 3D Outer Blood-Retinal Barrier with Advanced Choriocapillaris and Its Application in Diabetic Retinopathy in a Microphysiological System

The outer blood-retinal barrier (oBRB) provides an optimal environment for the function of the photoreceptor by regulating the exchange of molecules between subretinal space and the choriocapillaris, and its dysfunction could impair the photoreceptor's function and vision. The existing in vitro models have limitations in reproducing the barrier function or physiological characteristics of oBRB and choriocapillaris. Here, we engineered a microphysiological system-based oBRB-choriocapillaris model that simultaneously incorporates the desired physiological characteristics and is simple to fabricate. First, we generated microvascular networks to mimic choriocapillaris and investigated the role of fibroblasts in vasculogenesis. By adding retinal pigment epithelial cells to one side of blood vessels formed with endothelial cells and fibroblasts and optimizing their culture medium conditions, we established an oBRB-choriocapillaris model. To verify the physiological similarity of our oBRB-choriocapillaris model, we identified the polarization and expression of the tight junction of the retinal pigment epithelium, Bruch's membrane, and the fenestral diaphragm of choriocapillaris. Finally, we tried to recapitulate the diabetes mellitus environment in our model with hyperglycemia and diabetes-related cytokines. This induced a decrease in tight junction integrity, loss of barrier function, and shrinkage of blood vessels, similar to the in vivo pathological changes observed in the oBRB and choriocapillaris. The oBRB-choriocapillaris model developed using a microphysiological system is expected to offer a valuable in vitro platform for retinal and choroidal vascular diseases in preclinical applications.

Choroidal Vein Alterations in Pachychoroid Disease With Choroidal Vascular Hyperpermeability: Evaluated by Wide-Field Indocyanine Green Angiography

Purpose

The purpose of this study was to investigate choroidal vein (ChV) morphological features in pachychoroid disease (PCD) with choroidal vascular hyperpermeability (CVH).

Methods

This retrospective study assessed subfoveal choroidal thickness (SFCT) and CVH area numbers and locations of recruited patients with PCD using multimodal images. ChV alteration patterns, including fusiform, bulbosity, sausaging, confluence, and anastomoses, as well as asymmetric ChVs, dominant ChVs, and non-dominant ChVs, were evaluated using wide-field indocyanine green angiograms.

Results

Of 68 PCD eyes from 35 patients (mean age: 46.16 ± 6.28 years, 71.4% men), 2.9% had uncomplicated pachychoroid, 32.4% had pachychoroid pigment epitheliopathy (PPE), 55.9% central serous chorioretinopathy (CSC), and 8.8% pachychoroid neovasculopathy (PNV). Mean SFCT was 468.65 ± 131.40 µm. Among 419 CVH areas, ChV fusiform, ChV bulbosity, and ChV sausaging accounted for 35.8%, 35.1%, and 29.1%, respectively; 21.2% had ChV confluence and 11.9% had ChV anastomoses. At CVH areas, 13.1% had retinal pigment epithelium (RPE) leakage. ChV fusiform is steadily declining (37.4%, 36.8%, and 22.9%, respectively), and ChV sausaging, ChV anastomoses, and ChV confluence are increased gradually in the PPE, CSC, and PNV groups (21.4%, 30.0%, and 37.1%; 11.4%, 11.1%, and 20.0%; and 19.8%, 20.9%, and 28.6%, respectively). Dominant ChVs had higher CVH area numbers than non-dominant ChVs in the PPE and CSC groups (P = 0.010, P = 0.001).

Conclusions

Different patterns of ChV alterations, including the newly identified ChV confluence, are commonly present at CVH areas in PCD. The CVH areas in PCD eyes are primarily located within the dominant ChVs. These findings provide crucial evidence for advancing our understanding of the underlying mechanisms of PCD pathogenesis.

The Role of Diabetic Choroidopathy in the Pathogenesis and Progression of Diabetic Retinopathy

Diabetic choroidopathy was first described on histopathological specimens of diabetic eyes. This alteration was characterized by the accumulation of PAS-positive material within the intracapillary stroma. Inflammation and polymorphonuclear neutrophils (PMNs) activation are crucial elements in choriocapillaris impairment. The evidence of diabetic choroidopathy in vivo was confirmed with multimodal imaging, which provides key quantitative and qualitative features to characterize the choroidal involvement. The choroid can be virtually affected in each vascular layer, from Haller's layer to the choriocapillaris. However, the damage on the outer retina and photoreceptor cells is essentially driven by a choriocapillaris deficiency, which can be assessed through optical coherence tomography angiography (OCTA). The identification of characteristic features of diabetic choroidopathy can be significant for understanding the potential pathogenic and prognostic implications in diabetic retinopathy.

Parapapillary Choroidal Microvasculature Predicts Diabetic Retinopathy Progression and Diabetic Macular Edema Development: A Three-Year Prospective Study

PURPOSE

To determine the predictive value of the microcirculation of the optic nerve head by swept-source optical coherence tomography angiography for identifying individuals with high risk of diabetic retinopathy (DR) progression and diabetic macular edema (DME) development.

DESIGN

Prospective observational cohort study.

METHODS

A total of 946 patients (1879 eyes) with type 2 diabetes mellitus were recruited who had no DR or mild nonproliferative DR at baseline, and no DME. All subjects underwent 3 × 3 mm swept-source optical coherence tomography angiography centered on the optic nerve head to generate angiograms in 4 layers: radial peripapillary plexus, superficial retinal capillary plexus (SCP), deep retinal capillary plexus, and choriocapillaris (CC). The CC flow deficit percentage (CC FD%), vessel density (VD), and perfusion density (PD) were quantified.

RESULTS

During the 3 consecutive years of follow-up, 312 eyes (16.60%) experienced DR progression and 115 eyes (6.12%) developed DME. The DR progression was related to a lower VD of the SCP (relative risk per standard deviation decrease, 95% confidence interval): 1.30, 1.14-1.48; P < .001), a lower PD of the SCP (1.41, 1.24-1.60; P < .001), a lower VD of the radial peripapillary plexus (1.23, 1.08-1.40; P = .002), and an elevated CC FD% (1.62, 1.40-1.88; P < .001). The DME occurrence was associated with a lower VD of SCP (1.35, 1.09-1.66; P = .005), a lower PD of SCP (1.29, 1.05-1.59; P = .016), and a higher CC FD% (1.29, 1.03-1.61; P < .001). The CC FD% significantly improved the predictive power, with the increase of the C-statistic for DR progression and DME occurrence by 3.83% (P = .002) and 5.24% (P < .001), respectively.

CONCLUSIONS

This study provides the first longitudinal evidence suggesting that peripapillary CC FD% can improve the prediction of DR progression and DME development beyond traditional risk factors.

Dilated choroidal vascular channels in pachychoroid neovasculopathy

BACKGROUND

To elucidate the pattern of the choroidal vasculature in exudative pachychoroid neovasculopathy (PNV) and its correlation with the clinical course and treatment outcomes.

METHODS

The retrospective study included consecutive patients in National Taiwan University Hospital between 2014 and 2020 who fulfilled the criteria for exudative PNV defined as active type 1 macular neovascularization (MNV) on optical coherence tomography angiography (OCTA) and with leakage on fluorescein angiography (FA) or indocyanine green angiography (ICGA) associated with pachychoroid features. The corrected distance visual acuity (CDVA), FA, ICGA, and OCT images obtained by Optovue (Optovue Inc, Freemont CA, USA) spectral domain OCT were evaluated at baseline and various time points during the 12-month treatment period. The correlations between the choroidal vascular patterns, specifically those with or without dilated choroidal vascular channels (DCVC) revealed by ICGA, and baseline characteristics and treatment outcomes were evaluated using multiple regression models.

RESULTS

The study enrolled 34 eyes of 31 patients. The average age was 59.0 ± 9.3 years, and 20 participants were men. ICGA revealed DCVCs in 21 eyes, while the remaining 13 eyes did not have DCVCs. At baseline, DCVC group was older (p = 0.03) and had a longer duration of visual symptoms (p = 0.02), with a higher vessel density (defined as the percentage of the measured area occupied by flow area) of MNV (p = 0.04), higher proportion of ellipsoid zone disruption (p = 0.01), and poorer CDVA (p = 0.03). After the 12-month treatment period, the frequency of requirement of anti-VEGF injections (p < 0.01) was higher, and the risk for CDVA <20/40 was higher (adjusted OR: 5.29, 95% CI: 1.24-22.48, p = 0.02) in eyes with DCVCs.

CONCLUSIONS

For PNV, eyes with DCVCs were associated with higher vessel density of macular neovascularization and poorer CDVA at baseline, and had poorer visual and anatomical outcomes although more anti-VEGF injections were given.

Pathogenic Risk Factors and Associated Outcomes in the Bullous Variant of Central Serous Chorioretinopathy

PURPOSE

To compare the clinical features, treatments, and outcomes between bullous and chronic variants of central serous chorioretinopathy (CSC).

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Sixty-two eyes of 44 patients with bullous-variant CSC (bvCSC) and 97 eyes of 85 patients with nonbullous CSC.

METHODS

We conducted a national survey between September 1, 2020, and March 31, 2021, of members of the Korean Retina Society and obtained data of patients with bvCSC from 11 retinal centers. A comparator group comprised consecutive chronic CSC patients without bullous detachment.

MAIN OUTCOME MEASURES

Baseline demographics and patient characteristics were compared between groups. Secondary outcomes included factors associated with visual prognosis within the bvCSC group.

RESULTS

Compared with the nonbullous CSC group, the bvCSC group presented at a younger age (49 vs. 52 years; P = 0.047) and with more bilateral involvement (41% vs. 14%; P < 0.001). Systemic corticosteroid use was more prevalent in the bvCSC group, both in terms of any exposure (50% vs. 20%; P = 0.001) and long-term exposure (36% vs. 9%; P <  0.001). The bvCSC group had distinct imaging features (all P < 0.05): retinal folding (64% vs. 1%), subretinal fibrin (75% vs. 13%), multiple retinal pigment epithelium tears (24% vs. 2%), and multifocal fluorescein leakages with terminal telangiectasia (36% vs. 1%). Although bvCSC patients had worse vision at diagnosis (20/80 vs. 20/44; P =  0.003), treatment response was more robust (fluid resolution by final follow-up, 84% vs. 68%; P = 0.034) even with conservative management, resulting in similar final vision (20/52 vs. 20/45; P =  0.52). History of kidney-related (odds ratio [OR] 5.4; 95% confidence interval [CI] 1.3-18.5; P =  0.045) and autoimmune/rheumatoid diseases (OR 25.4, 95% CI 2.8-195.0; P =  0.004) showed associations with the bvCSC group. Apart from vision at diagnosis (OR 0.1, 95% CI 0.05-0.36; P  <  0.001), a history of renal transplantation was most predictive of visual prognoses for bvCSC eyes (OR 0.2, 95% CI 0.04-0.75; P  =  0.020).

CONCLUSIONS

Bullous-variant CSC may be associated with pathogenic risk factors based on underlying medical conditions and systemic corticosteroid use. Poor vision at diagnosis and history of renal transplantation were associated with poor visual outcome.

Crossover to Half-Dose Photodynamic Therapy or Eplerenone in Chronic Central Serous Chorioretinopathy Patients

PURPOSE

To compare the efficacy and safety of crossover treatment to half-dose photodynamic therapy (PDT) and eplerenone treatment after the failure of primary treatment in patients with chronic central serous chorioretinopathy (cCSC).

DESIGN

Multicenter crossover clinical trial.

SUBJECTS

At 3 months after the baseline visit of the SPECTRA (Half-Dose Photodynamic Therapy Versus Eplerenone: Treatment Trial for Chronic Central Serous Chorioretinopathy) randomized controlled trial, either half-dose PDT or eplerenone treatment was evaluated for each patient, and patients who still demonstrated subretinal fluid (SRF) were included in the current study, the SPECS (Central Serous Chorioretinopathy Treated with Half-Dose PDT or Eplerenone Crossover Study) trial.

METHODS

At the baseline visits for the current SPECS trial, crossover treatment was performed for patients who still demonstrated SRF. These patients received either half-dose PDT or oral eplerenone for 12 weeks. Both anatomic and functional parameters were evaluated 3 months after crossover treatment.

MAIN OUTCOME MEASURES

Complete resolution of SRF on OCT.

RESULTS

Forty-nine patients were included in the SPECS trial (38 received primary eplerenone treatment; 11 received half-dose PDT). At 3 months after crossover treatment, 32 of 37 (86.5%) in the crossover to half-dose PDT group and 2 of 9 (22.2%) in the crossover to eplerenone group had complete SRF resolution (P = 0.030). The mean foveal sensitivity increased significantly more in the crossover to half-dose PDT group (mean, +3.08 dB) compared with the crossover to eplerenone group (mean, -0.27 dB; P = 0.009).

CONCLUSIONS

Patients with cCSC with the persistence of SRF after primary eplerenone treatment can benefit from half-dose PDT, which can induce a relatively fast and complete SRF resolution, along with an improvement in foveal sensitivity.

Non-vasogenic cystoid maculopathies

Besides cystoid macular edema due to a blood-retinal barrier breakdown, another type of macular cystoid spaces referred to as non-vasogenic cystoid maculopathies (NVCM) may be detected on optical coherence tomography but not on fluorescein angiography. Various causes may disrupt retinal cell cohesion or impair retinal pigment epithelium (RPE) and Müller cell functions in the maintenance of retinal dehydration, resulting in cystoid spaces formation. Tractional causes include vitreomacular traction, epiretinal membranes and myopic foveoschisis. Surgical treatment does not always allow cystoid space resorption. In inherited retinal dystrophies, cystoid spaces may be part of the disease as in X-linked retinoschisis or enhanced S-cone syndrome, or occur occasionally as in bestrophinopathies, retinitis pigmentosa and allied diseases, congenital microphthalmia, choroideremia, gyrate atrophy and Bietti crystalline dystrophy. In macular telangiectasia type 2, cystoid spaces and cavitations do not depend on the fluid leakage from telangiectasia. Various causes affecting RPE function may result in NVCM such as chronic central serous chorioretinopathy and paraneoplastic syndromes. Non-exudative age macular degeneration may also be complicated by intraretinal cystoid spaces in the absence of fluorescein leakage. In these diseases, cystoid spaces occur in a context of retinal cell loss. Various causes of optic atrophy, including open-angle glaucoma, result in microcystoid spaces in the inner nuclear layer due to a retrograde transsynaptic degeneration. Lastly, drug toxicity may also induce cystoid maculopathy. Identifying NVCM on multimodal imaging, including fluorescein angiography if needed, allows guiding the diagnosis of the causative disease and choosing adequate treatment when available.

Pachychoroid Spectrum Diseases in Patients with Cushing’s Syndrome: A Systematic Review with Meta-Analyses

Cushing’s syndrome is a rare disease with an endogenous cause of excess cortisol secretion. More evidence substantially links cortisol levels to the pachychoroid spectrum diseases. In this systematic review and meta-analysis, we summarize available evidence on pachychoroid spectrum diseases in patients with Cushing’s syndrome. We performed a systematic literature search in 11 databases on 21 May 2022. Studies were considered eligible if they performed retinal examination of a consecutive group of patients with Cushing’s syndrome using optical coherence tomography (OCT) scans. We extracted data on subfoveal choroidal thickness in patients with Cushing’s syndrome compared to matched controls. We also extracted data on the prevalence of pachychoroid pigment epitheliopathy (PPE), central serous chorioretinopathy (CSC), and polypoidal choroidal vasculopathy (PCV). We identified six eligible studies with a total of 159 patients with Cushing’s syndrome. On average, patients with Cushing’s syndrome have 49.5 µm thicker subfoveal choroidal thickness compared to matched healthy individuals. Pachychoroid spectrum diseases were relatively common in these patients: PPE in 20.8%, CSC in 7.7%, and PCV in 2.8%. We conclude that there should be low threshold to recommend ophthalmic examination to patients with Cushing’s syndrome, and that a macular OCT is recommended during this examination.

Correlation between Choroidal Vascularity Index and Outer Retina in Patients with Diabetic Retinopathy

The choroid supplies blood to the outer retina. We quantified outer retinal and choroidal parameters to understand better the pathogenesis of diabetic retinopathy (DR) and diabetic macular edema (DME). The retrospective cross-sectional single-center study included 210 eyes from 139 diabetic patients and 76 eyes from 52 healthy controls. Spectral-domain optical coherence tomography (OCT) was carried out with a Spectralis HRA + OCT imaging device. The outer retinal layer (ORL), outer nuclear layer (ONL), and choroidal thicknesses were assessed along with the choroidal vascularity index (CVI). The presence of DR, whether with DME or without, was associated with choroidal thinning (p < 0.001). Compared with the controls, patients with DR without DME presented with lower ORL and ONL thickness (p < 0.001), whereas those with DR and DME had higher values of both parameters (p < 0.001). Significant correlations between outer retinal and choroidal parameters were found only in patients with DR without DME (ORL with choroidal thickness: p = 0.003, rho = 0.34; ORL with CVI: p < 0.001, rho = 0.49, ONL with CVI: p < 0.027, rho = 0.25). No correlations between choroidal and outer retinal parameters were observed in the controls and patients with DR and concomitant DME. Aside from diabetic choroidopathy, other pathogenic mechanisms seem to predominate in the latter group.

Variability in Retinal Neuron Populations and Associated Variations in Mass Transport Systems of the Retina in Health and Aging

Aging is associated with a broad range of visual impairments that can have dramatic consequences on the quality of life of those impacted. These changes are driven by a complex series of alterations affecting interactions between multiple cellular and extracellular elements. The resilience of many of these interactions may be key to minimal loss of visual function in aging; yet many of them remain poorly understood. In this review, we focus on the relation between retinal neurons and their respective mass transport systems. These metabolite delivery systems include the retinal vasculature, which lies within the inner portion of the retina, and the choroidal vasculature located externally to the retinal tissue. A framework for investigation is proposed and applied to identify the structures and processes determining retinal mass transport at the cellular and tissue levels. Spatial variability in the structure of the retina and changes observed in aging are then harnessed to explore the relation between variations in neuron populations and those seen among retinal metabolite delivery systems. Existing data demonstrate that the relation between inner retinal neurons and their mass transport systems is different in nature from that observed between the outer retina and choroid. The most prominent structural changes observed across the eye and in aging are seen in Bruch’s membrane, which forms a selective barrier to mass transfers at the interface between the choroidal vasculature and the outer retina.

Verteporfin-mediated on/off photoswitching functions synergistically to treat choroidal vascular diseases

Choroidal vascular diseases, such as age-related macular degeneration, are the leading cause of vision impairment and are characterized by pathological angiogenesis. Verteporfin-mediated photodynamic therapy is a current strategy that selectively occludes choroidal neovasculature. However, the clinically used large-dose systemic administration increases the risk of systemic adverse events, such as phototoxicity to superficial tissues. In this study, we developed an in situ verteporfin delivery system with a photoswitching synergistic function that disassembles in response to intraocular inflammatory enzymes. Under light-on conditions, verteporfin-mediated photodynamic therapy effectively occurs and this leads to vascular occlusion. Under light-off conditions, non-photoactive verteporfin negatively regulates vascular endothelial growth factor-induced angiogenesis as a yes-associated protein inhibitor. Taken together, our system serves as an intraocular verteporfin reservoir to improve the bioavailability of verteporfin by innovatively exploiting its photochemical and biological functions. This work provides a promising strategy with synergistic antiangiogenic effects for the treatment of choroidal vascular diseases.

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For the first time, an intraocular verteporfin delivery system with on/off photoswitching synergistic functions is reported.

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VP-TGMS with light-on effectively leads to occlusion of choroidal pathological neovascularization via photodynamic mechanism.

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VP-TGMS with light-off significantly suppresses VEGF-induced angiogenesis via YAP signaling inhibition.

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This study provides a promising strategy for the treatment of choroidal vascular diseases.

The Cortisol Response of Male and Female Choroidal Endothelial Cells: Implications for Central Serous Chorioretinopathy

CONTEXT

Central serous chorioretinopathy (CSC) is a severe ocular disease characterized by fluid accumulation under the retina and abnormalities in the underlying vascular layer, the choroid. CSC has a striking prevalence in males of 80% to 90% of total patients. Corticosteroids are the most pronounced extrinsic risk factor for CSC. Choroidal endothelial cells (CECs) are important for the vascular integrity of the choroid, but the effects of corticosteroid effects in these cells are unknown.

OBJECTIVE

We aimed to reveal the potential steroidal contribution to CSC.

METHOD

We characterized the expression of the glucocorticoid, mineralocorticoid, and androgen receptor in the human choroid using immunohistochemistry. Using RNA-sequencing, we describe the cortisol response in human CECs derived from 5 male and 5 female postmortem donors.

RESULTS

The glucocorticoid receptor was highly expressed in the human choroid, whereas no to minimal expression of the mineralocorticoid and androgen receptors was observed. The extensive transcriptional response to cortisol in human primary cultured CECs showed interindividual differences but very few sex differences. Several highly regulated genes such as ZBTB16 (log2 fold change males 7.9; females 6.2) provide strong links to choroidal vascular regulation.

CONCLUSIONS

The glucocorticoid receptor predominantly mediates the response to cortisol in human CECs. Interindividual differences are an important determinant regarding the cortisol response in human cultured CECs, whereas intrinsic sex differences appear less pronounced. The marked response of particular target genes in endothelial cells to cortisol, such as ZBTB16, warrants further investigation into their potential role in the pathophysiology of CSC and other vascular conditions.