Proteome and Metabolome of Subretinal Fluid in Central Serous Chorioretinopathy and Rhegmatogenous Retinal Detachment: A Pilot Case Study

Metabolomic Signature in Men with Central Serous Chorioretinopathy Using UHPLC-MS

Central serous chorioretinopathy (CSCR), the fourth leading cause of retinal disease, tends to affect men and is favored by corticosteroids. Untargeted systemic metabolomics was analyzed in 60 men with CSCR and 60 age-matched controls using UHPLC-MS. The analysis of sera revealed a total of 722 metabolites that differed significantly between the CSCR and control groups, with 592 being downregulated and 130 being upregulated. The metabolic profile exhibited incomplete breakdown products of protein digestion or catabolism, incomplete fatty acid β-oxidation, and alterations in antioxidant metabolism. A substantial upregulation of three primary fatty acid amides was observed, along with a downregulation of long-chain acylcarnitines and kynurenines. The reduction in long- and medium-chain acylcarnitine, sphingosine-1-phosphate (S1P), tryptophan, and kynurenine, all of which are upregulated by glucocorticoids, does not support the hypothesis of excess glucocorticoid in patients with CSCR. In conclusion, we report here that patients with CRSC present a metabolic signature that could be useful as a complement to specific endocrine studies to better understand the relationship between corticoids and the pathology. Repeated cohorts are needed to validate these findings.

Vitreous proteomics in rhegmatogenous retinal detachment and proliferative vitreoretinopathy

Rhegmatogenous retinal detachment (RRD) is a serious ophthalmic condition that, if untreated, can result in significant vision loss. Proliferative vitreoretinopathy (PVR) often complicates RRD and is the leading cause of surgical failure. Proteomic analysis of the vitreous has emerged as a powerful tool for elucidating the molecular mechanisms underlying RRD and PVR. This article reviews proteomic findings related to these conditions. A comprehensive literature search on PubMed was conducted, focusing on studies of vitreous proteomics in RRD and PVR published between 1988 and August 2024. Relevant findings on protein expression, metabolic pathways, and therapeutic targets were synthesized. Proteomic studies reveal significant alterations in photoreceptor-specific proteins, such as rhodopsin and Monocyte Chemoattractant Protein-1 (MCP-1), associated with apoptosis and inflammation during RRD. Metabolic dysregulation is evidenced by changes in glycolytic enzymes and antioxidants, including downregulation of peroxiredoxin-2 and ascorbic acid, suggesting impaired energy production and oxidative stress. Elevated cytokines, complement proteins, and matrix metalloproteinases highlight the role of inflammation and extracellular matrix remodelling in disease progression. Cytokine expression in PVR demonstrates distinct temporal patterns, with early stages marked by T-cell activation and mTOR pathway-related cytokines, and advanced stages characterized by monocyte chemoattractants associated with chronic inflammation. Currently, the potential of pharmacologic interventions in RRD and PVR remains limited. In contrast, proteomics offers critical insights into molecular mechanisms, identifying potential biomarkers and therapeutic pathways. The adoption of single-molecule and top-down proteomics, along with the integration of advanced technologies with artificial intelligence and bioinformatics, holds promise for accelerating progress toward precision medicine. These developments represent a promising avenue for future research and clinical application.

Subretinal hyporeflective globule: A novel OCT finding in central serous chorioretinopathy

PURPOSE

To describe the subretinal hyporeflective globule in cases of central serous chorioretinopathy (CSC).

METHODS

A retrospective analysis of consecutive cases of CSC presenting to a tertiary eye care center in eastern India was conducted. Subretinal hyporeflective globules were identified as small globular lesions below the external limiting membrane/ellipsoid zone, but above the RPE layer. They had a hyperreflective border with a hyporeflective core and a clear posterior tail of hyper-transmission.

RESULTS

The present study analyzed 137 eyes of 137 patients. Eighty (58.4%) eyes had acute disease at presentation, 48 (35%) eyes had chronic disease, and eight (5.8%) eyes had resolved CSC. Subretinal hyporeflective globules were seen in 27 (21.8%) eyes, of which choroidal caverns were seen in seven (5.1%) eyes. Twenty-five eyes with chronic CSC and only two eyes with acute CSC had subretinal hyporeflective globules. Three eyes with resolved CSC had subretinal hyporeflective globules.

CONCLUSION

We describe subretinal hyporeflective globule as a novel optical coherence tomography (OCT) finding in cases of CSC and describe its clinical correlates.

Applications of artificial intelligence and bioinformatics methodologies in the analysis of ocular biofluid markers: a scoping review

PURPOSE

This scoping review summarizes the applications of artificial intelligence (AI) and bioinformatics methodologies in analysis of ocular biofluid markers. The secondary objective was to explore supervised and unsupervised AI techniques and their predictive accuracies. We also evaluate the integration of bioinformatics with AI tools.

METHODS

This scoping review was conducted across five electronic databases including EMBASE, Medline, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science from inception to July 14, 2021. Studies pertaining to biofluid marker analysis using AI or bioinformatics were included.

RESULTS

A total of 10,262 articles were retrieved from all databases and 177 studies met the inclusion criteria. The most commonly studied ocular diseases were diabetic eye diseases, with 50 papers (28%), while glaucoma was explored in 25 studies (14%), age-related macular degeneration in 20 (11%), dry eye disease in 10 (6%), and uveitis in 9 (5%). Supervised learning was used in 91 papers (51%), unsupervised AI in 83 (46%), and bioinformatics in 85 (48%). Ninety-eight papers (55%) used more than one class of AI (e.g. > 1 of supervised, unsupervised, bioinformatics, or statistical techniques), while 79 (45%) used only one. Supervised learning techniques were often used to predict disease status or prognosis, and demonstrated strong accuracy. Unsupervised AI algorithms were used to bolster the accuracy of other algorithms, identify molecularly distinct subgroups, or cluster cases into distinct subgroups that are useful for prediction of the disease course. Finally, bioinformatic tools were used to translate complex biomarker profiles or findings into interpretable data.

CONCLUSION

AI analysis of biofluid markers displayed diagnostic accuracy, provided insight into mechanisms of molecular etiologies, and had the ability to provide individualized targeted therapeutic treatment for patients. Given the progression of AI towards use in both research and the clinic, ophthalmologists should be broadly aware of the commonly used algorithms and their applications. Future research may be aimed at validating algorithms and integrating them in clinical practice.

Shotgun lipidomics of human subretinal fluids under rod-dominant retina reveals cone-dominated lipids

Subretinal fluid (SRF) accumulates between photoreceptor outer segments and retinal pigment epithelium during rhegmatogenous retinal detachment. Biomolecular components such as lipids originate from cells surrounding the SRF. Knowledge of the composition of these molecules in SRF potentially provides mechanistic insight into the physiologic transfer of lipids between retinal tissue compartments. Using mass spectrometry and tandem mass spectrometry analysis on an electrospray ionization quadrupole-time-of-flight mass spectrometer, we identified a total of 115 lipid molecular species of 11 subclasses and 9 classes in two samples from two patients with rhegmatogenous retinal detachment. These included 47 glycerophosphocholines, 6 glycerophosphoethanolamines, 1 glycerophosphoinositol, 18 sphingomyelins, 9 cholesteryl esters, free cholesterol, 3 ceramides, 22 triacylglycerols and 8 free fatty acids. Glycerophosphocholines were of the highest intensity. By minimizing the formation of different adduct forms or clustering ions of different adducts, we determined the relative intensity of lipid molecular species within the same subclasses. The profiles were compared with those of retinal cells available in the published literature. The glycerophosphocholine profile of SRF was similar to that of cone outer segments, suggesting that outer segment degradation products are constitutively released into the interphotoreceptor matrix, appearing in SRF during detachment. This hypothesis was supported by the retinal distributions of corresponding lipid synthases' mRNA expression obtained from an online resource based on publicly available single-cell sequencing data. In contrast, based on lipid profiles and relevant gene expression in this study, the sources of free cholesterol and cholesteryl esters in SRF appeared more ambiguous, possibly reflecting that outer retina takes up plasma lipoproteins. Further studies to identify and quantify lipids in SRF will help better understand etiology of diseases relevant to outer retina.

An update in the applications of exosomes in cancer theranostics: from research to clinical trials

Exosomes are nanosized extracellular vesicles secreted by nearly all viable cells following the fusing of multivesicular bodies and the plasma membrane and discharged into the encircling bodily fluids. Exosomes can transport cell-specific components from the source cell to the target cell. Given the enormous potential of exosomes as non-invasive diagnostic biomarkers and therapeutic nanovehicles. Lately, accumulated evidence has demonstrated that exosomes serve an important role in prognosis, diagnosis, and even treatment strategies. While several reviews have collective information on the biomedical application of exosomes, a comprehensive review incorporating updated and improved methodologies for beneficial applications of such vesicles in cancer theranostics is indispensable. In the current review, we first provided a comprehensive review of the introduction of exosomes, featuring their discovery, separation, characterization, function, biogenesis, secretion. The implications of exosomes as promising nanovehicles for drug and gene delivery, application of exosome inhibitors in the management of cancers, completed and ongoing clinical trials on the biological relevance of exosomes are then discussed in detail. As the field of exosome research grows, a better understanding of the subcellular parts and mechanisms involved in exosome secretion and targeting of specific cells will help figure out what their exact physiological functions are in the body.

URINARY METABOLOMICS OF CENTRAL SEROUS CHORIORETINOPATHY

PURPOSE

To analyze the urinary metabolomic profile of central serous chorioretinopathy cases.

METHODS

In a cross-sectional study, 80 participants with central serous chorioretinopathy were compared with 80 age-matched and sex-matched controls. Urinary metabolites were measured using Metabolon's Discovery HD4 platform.

RESULTS

Of 1,031 metabolites total that were measured in urine samples, 53 were upregulated and 27 downregulated in central serous chorioretinopathy participants compared with controls. After exclusion of potentially confounding xenobiotics and bile compounds that could represent digestive processes, 14 metabolites were significantly higher and 12 metabolites were significantly lower in cases compared with controls. One upregulated metabolite (tetrahydrocortisol sulfate) is involved in the corticosteroid subpathway. The downregulated metabolites are unrelated to the identified corticosteroid subpathway.

CONCLUSION

The upregulation of urinary tetrahydrocortisol sulfate in central serous chorioretinopathy cases provides a precise molecular basis to further study the role of corticosteroids in producing choroidal venous congestion.

Aldosterone as a Possible Contributor to Eye Diseases

Aldosterone, an effector molecule of the renin-angiotensin-aldosterone system (RAAS), has been receiving more attention in the field of ophthalmology because of its possible role in the pathogenesis of various eye diseases or abnormalities; it may even become a target for their treatment. Primary aldosteronism, a typical model of a systemic aldosterone excess, may cause vision loss due to various ocular diseases, such as retinal vein occlusion, central serous chorioretinopathy, and, possibly glaucoma. RAAS components are present in various parts and types of cells present in the eye. Investigations of the local RAAS in various animal models of diabetic macular edema, retinal vein occlusion, retinopathy of prematurity, central serous chorioretinopathy, and glaucoma have found evidence that aldosterone or mineralocorticoid receptors may exacerbate the pathology of these disorders. Further studies are needed to elucidate whether the modulation of aldosterone or mineralocorticoid receptors is an effective treatment for preventing vision loss in patients with eye diseases.

Does choroidal thickness predict persistent subretinal fluid after rhegmatogenous retinal detachment repair? A retrospective study with fellow eye comparison

PURPOSE

To evaluate whether choroidal thickness (CT) is associated with persistent subretinal fluid (pSRF) after simple primary rhegmatogenous retinal detachment (RRD) repair.

METHODS

This single-centre, retrospective, observational study included patients who underwent RRD repair with at least 12-month follow-up. Preoperative and postoperative parameters were evaluated for association with pSRF. CT measurements were obtained at the central 1 mm area on enhanced depth imaging (EDI) OCT scans, using a semiautomatic method. Multiple logistic regression analyses were assessed to determine predictive factors for pSRF.

RESULTS

Overall, 100 eyes of 100 patients, mean age of 59.9 ± 12.6 years were included. pSRF was found in 21.0% of eyes and resolved over time in 85.7% of eyes at 12 months. In the pSRF group both RRD and fellow eyes showed lower mean choroidal and RPE thickness values as compared to those without pSRF (p < 0.05). A significant correlation was found between pSRF occurrence and choroidal thinning (p = 0.02). After multiple regression analyses, macula-off RRD (p = 0.005) and scleral buckling (SB) technique (p = 0.001) were retained as final predictors for pSRF. In macula-off SB eyes, detachment duration was the only factor associated with pSRF (p = 0.046). There were no significant differences in best-corrected visual acuity outcomes between the pSRF and the no-pSRF eyes.

CONCLUSIONS

Patients with pSRF showed lower choroidal and RPE thickness as compared to those without pSRF. CT did not turn out to be a final predictor for pSRF, as this was mainly associated with macular involvement, surgical technique and detachment duration.

Transthyretin proteoforms of intraocular origin in human subretinal fluid

Understanding the molecular composition of ocular tissues and fluids could inform new approaches to prevalent causes of blindness. Subretinal fluid accumulating between the photoreceptor outer segments and retinal pigment epithelium (RPE) is potentially a rich source of proteins and lipids normally cycling among outer retinal cells and choroid. Herein, intact post-translationally modified proteins (proteoforms) were extracted from subretinal fluids of five patients with rhegmatogenous retinal detachment (RRD), analyzed by tandem mass spectrometry, and compared to published data on these same proteins as synthesized by other organs. Single-nuclei transcriptomic data from non-diseased human retina/RPE were used to identify whether proteins in subretinal fluid were of potential ocular origin. Two human donor eyes with normal maculas were immunoprobed for transthyretin (TTR) with appropriate controls. The three most abundant proteins detected in subretinal fluid were albumin, TTR, and apolipoprotein A-I. Remarkably, TTR relative to the other proteins was more abundant than its serum counterpart, suggestive of TTR being synthesized predominantly locally. Six post-translationally modified protein forms (proteoforms) of TTR were detected, with the relative amount of glutathionylated TTR being much higher in the subretinal fluid (12-43%) than values reported for serum (<5%) and cerebrospinal fluid (0.4-13%). Moreover, a putative glycosylated TTR dimer of 32,428 Da was detected as the fourth most abundant protein. The high abundance of TTR and putative TTR dimer in subretinal fluid was supported by analysis of available single-nuclei transcriptomic data, which showed strong and specific signal for TTR in RPE. Immunohistochemistry further showed strong diffuse TTR immunoreactivity in choroidal stroma that contrasted with vertically aligned signal in the outer segment zone of the subretinal space and negligible signal in RPE cell bodies. These results suggest that TTR in the retina is synthesized intraocularly, and glutathionylation is crucial for its normal function. Further studies on the composition, function, and quantities of TTR and other proteoforms in subretinal fluid could inform mechanisms, diagnostic methods, and treatment strategies for age-related macular degeneration, familial amyloidosis, and other retinal diseases involving dysregulation of physiologic lipid transfer and oxidative stress.

Association of central serous chorioretinopathy with single nucleotide polymorphisms in complement factor H gene in Iranian population

OBJECTIVES

To investigate the association of two different single nucleotide polymorphisms (SNPs) in the complement factor H (CFH) gene with central serous chorioretinopathy (CSCR) in the Iranian population.

METHODS

This is a case-control study with 95 participants in each group who were stratified according to their various ethnical variations. Primers for rs1329428 and rs3753394 polymorphisms were synthesized. DNA was extracted from peripheral blood leukocytes and underwent PCR and high-resolution melt analysis.

RESULTS

The frequency of tt, ct, and cc genotypes for rs1329428 polymorphism was 22 (26.5%), 46 (55.4%), and 15 (18.1%) in acute CSCR and 5 (41.7%), 5 (41.7%), and 2 (16.7%) in chronic CSCR respectively with no significant difference between case and control groups. The frequency of tt, ct, and cc genotypes for rs3753394 polymorphism was 31 (37.3%), 14 (16.9%), and 38 (45.8%) in acute CSCR and 4 (33.3%), 3 (25%), and 5 (41.7%) in chronic CSCR respectively. There was a significant difference between patients of Persian descent and controls in rs3753394 polymorphism (P = 0.00, chi-square test). There was no statistical difference in the frequency of polymorphism between acute and chronic patients (P = 0.64 and P = 0.79 respectively, chi-square test).

CONCLUSIONS

The rs3753394 polymorphism is probably associated with CSCR in Persian ethnicity. Further studies are required to validate the implications of this finding in clinical practice.

Pathophysiology of central serous chorioretinopathy: a literature review with quality assessment

The pathogenesis of central serous chorioretinopathy (CSCR), a pachychoroid disease, is poorly understood. While choroid hyperpermeability and retinal pigment epithelium dysfunction are cornerstones for developing CSCR, the mechanisms at the retinal, vascular, retinal pigment epithelium, and cellular level continue to be an enigma. A few preclinical studies and the development of small-sized, poorly controlled clinical trials have resulted in limited insight into the disease mechanism. Effective treatments for CSCR are still lacking as current trials have produced inconsistent results for functional and structural gains. Thus, critically evaluating the literature to explore disease mechanisms and provide an up-to-date understanding of pathophysiology can provide valuable information and avenues to new treatments. In this study, a comprehensive summary of the mechanistic insight into CSCR is presented while highlighting the shortcomings of current literature. The mechanism was divided into seven sub-categories including mechanical obstruction, inflammation, oxidative stress, paracrine factors, autonomic dysfunction, mineralocorticoid receptors activation, and medications. We implemented validated tools like the JBI and CAMARADES to objectively analyze the quality of both clinical and preclinical studies, respectively. Overall, our analysis of the literature showed that no single mechanism was populated with a large number of sufficiently sized and good-quality studies. However, compiling these studies gave hints not only to CSCR pathogenesis but also pachychoroid disease in general while providing suggestions for future exploration.

Increased risk for central serous chorioretinopathy in nephrotic syndrome patients: A population-based cohort study

BACKGROUND

Nephrotic syndrome (NS) is characterized by various etiologies that damage the glomerulus. Central serous chorioretinopathy (CSCR) is a retinal disease characterized by neurosensory detachment of the retina. Several case reports have described the relationship between both. Therefore, we try to analyze the epidemiological associations between NS and CSCR using the National Health Insurance Research Database in Taiwan.

METHODS

Data spanning 14 years were extracted from the National Health Insurance Research Database and sub-grouped. The variables were analyzed using Pearson's chi-squared test and Fisher's exact test. The risk factors for disease development with or without comorbidities were examined using an adjusted hazard ratio (aHR). Kaplan-Meier analysis was performed to evaluate the cumulative incidence of CSCR with or without NS.

RESULTS

A total of 14 794 patients with NS and 14 794 matched controls without NS were enrolled in this cohort study. The incidence rate of CSCR was higher in the study cohort than in the control cohort (aHR = 3.349, p < 0.001). The overall incidence of CSCR was 44.51 per 100 000 person-years in the study cohort and 33.39 per 100 000 person-years in the control cohort. In both groups, CSCR occurred more frequently in males than in females. Patients aged 40-49, 50-59, and ≥60 years in the study cohort had a significantly higher risk of developing CSCR than those in the control cohort (aHR = 3.445, 5.421, and 4.957, all p < 0.001). NS patient with a 4-week history of steroid usage has a higher risk of developing CSCR (aHR = 2.010, p < 0.001).

CONCLUSION

Our data showed that patients with NS have an increased risk of developing subsequent CSCR. Physician should routinely refer their NS patients to ophthalmologist for ophthalmic evaluation. This is the first nationwide epidemiological study reporting the association between these two diseases. Further studies are needed to clarify this relationship.

METABOLOMICS REVEALS BIOMARKERS IN HUMAN URINE AND PLASMA TO PREDICT CYP2D6 ACTIVITY

Background and Purpose

Individualized assessment of cytochrome P450 2D6 (CYP2D6) activity is usually performed through phenotyping following administration of a probe drug to measure the enzyme's activity. To avoid any iatrogenic harm (allergic drug reaction, dosing error) related to the probe drug, the development of non‐burdensome tools for real‐time phenotyping of CYP2D6 could significantly contribute to precision medicine. This study focuses on the identification of markers of the CYP2D6 enzyme in human biofluids using an LC‐high‐resolution mass spectrometry‐based metabolomic approach.

Experimental Approach

Plasma and urine samples from healthy volunteers were analysed before and after intake of a daily dose of paroxetine 20 mg over 7 days. CYP2D6 genotyping and phenotyping, using single oral dose of dextromethorphan 5 mg, were also performed in all participants.

Key Results

We report four metabolites of solanidine and two unknown compounds as possible novel CYP2D6 markers. Mean relative intensities of these features were significantly reduced during the inhibition session compared with the control session (n = 37). Semi‐quantitative analysis showed that the largest decrease (−85%) was observed for the ion m/z 432.3108 normalized to solanidine (m/z 398.3417). Mean relative intensities of these ions were significantly higher in the CYP2D6 normal–ultrarapid metabolizer group (n = 37) compared with the poor metabolizer group (n = 6). Solanidine intensity was more than 15 times higher in CYP2D6‐deficient individuals compared with other volunteers.

Conclusion and Implications

The applied untargeted metabolomic strategy identified potential novel markers capable of semi‐quantitatively predicting CYP2D6 activity, a promising discovery for personalized medicine.

Oral Ursodeoxycholic Acid Crosses the Blood Retinal Barrier in Patients with Retinal Detachment and Protects Against Retinal Degeneration in an Ex Vivo Model

Rhegmatogenous retinal detachment (RD) is a threatening visual condition and a human disease model for retinal degenerations. Despite successful reattachment surgery, vision does not fully recover, due to subretinal fluid accumulation and subsequent photoreceptor cell death, through mechanisms that recapitulate those of retinal degenerative diseases. Hydrophilic bile acids are neuroprotective in animal models, but whether they can be used orally for retinal diseases is unknown. Ursodeoxycholic acid (UDCA) being approved for clinical use (e.g., in cholestasis), we have evaluated the ocular bioavailability of oral UDCA, administered to patients before RD surgery. The level of UDCA in ocular media correlated with the extent of blood retinal barrier disruption, evaluated by the extent of detachment and the albumin concentration in subretinal fluid. UDCA, at levels measured in ocular media, protected photoreceptors from apoptosis and necrosis in rat retinal explants, an ex vivo model of RD. The subretinal fluid from UDCA-treated patients, collected during surgery, significantly protected rat retinal explants from cell death, when compared to subretinal fluid from control patients. Pan-transcriptomic analysis of the retina showed that UDCA upregulated anti-apoptotic, anti-oxidant, and anti-inflammatory genes. Oral UDCA is a potential neuroprotective adjuvant therapy in RD and other retinal degenerative diseases and should be further evaluated in a clinical trial.

Serous business: Delineating the broad spectrum of diseases with subretinal fluid in the macula

A wide range of ocular diseases can present with serous subretinal fluid in the macula and therefore clinically mimic central serous chorioretinopathy (CSC). In this manuscript, we categorise the diseases and conditions that are part of the differential diagnosis into 12 main pathogenic subgroups: neovascular diseases, vitelliform lesions, inflammatory diseases, ocular tumours, haematological malignancies, paraneoplastic syndromes, genetic diseases, ocular developmental anomalies, medication-related conditions and toxicity-related diseases, rhegmatogenous retinal detachment and tractional retinal detachment, retinal vascular diseases, and miscellaneous diseases. In addition, we describe 2 new clinical pictures associated with macular subretinal fluid accumulation, namely serous maculopathy with absence of retinal pigment epithelium (SMARPE) and serous maculopathy due to aspecific choroidopathy (SMACH). Differentiating between these various diseases and CSC can be challenging, and obtaining the correct diagnosis can have immediate therapeutic and prognostic consequences. Here, we describe the key differential diagnostic features of each disease within this clinical spectrum, including representative case examples. Moreover, we discuss the pathogenesis of each disease in order to facilitate the differentiation from typical CSC.

DBnorm as an R package for the comparison and selection of appropriate statistical methods for batch effect correction in metabolomic studies

As a powerful phenotyping technology, metabolomics provides new opportunities in biomarker discovery through metabolome-wide association studies (MWAS) and the identification of metabolites having a regulatory effect in various biological processes. While mass spectrometry-based (MS) metabolomics assays are endowed with high throughput and sensitivity, MWAS are doomed to long-term data acquisition generating an overtime-analytical signal drift that can hinder the uncovering of real biologically relevant changes. We developed “dbnorm”, a package in the R environment, which allows for an easy comparison of the model performance of advanced statistical tools commonly used in metabolomics to remove batch effects from large metabolomics datasets. “dbnorm” integrates advanced statistical tools to inspect the dataset structure not only at the macroscopic (sample batches) scale, but also at the microscopic (metabolic features) level. To compare the model performance on data correction, “dbnorm” assigns a score that help users identify the best fitting model for each dataset. In this study, we applied “dbnorm” to two large-scale metabolomics datasets as a proof of concept. We demonstrate that “dbnorm” allows for the accurate selection of the most appropriate statistical tool to efficiently remove the overtime signal drift and to focus on the relevant biological components of complex datasets.

Experimental models and examination methods of retinal detachment

Retinal detachment refers to the separation of the retinal neuroepithelium and pigment epithelium, usually involving the death of photoreceptor cells. Severe detachment may lead to permanent visual impairment if not treated properly and promptly. According to the underlying causes, retinal detachment falls into one of three categories: exudative retinal detachment, traction detachment, and rhegmatogenous retinal detachment. Like many other diseases, it is difficult to study the pathophysiology of retinal detachment directly in humans, because the human retinal tissues are precious, scarce and non-regenerative; thus, establishing experimental models that better mimic the disease is necessary. In this review, we summarize the existing models of the three categories of retinal detachment both in vivo and in vitro, along with an overview of their examination methods and the major strengths and weaknesses of each model.

Central serous chorioretinopathy: An update on risk factors, pathophysiology and imaging modalities

Central serous chorioretinopathy (CSC) is a common form of vision loss, typically seen in working-age men. The pathophysiology behind CSC still eludes us, however significant advances have been made in understanding this disease over the last decade using information from genetic and cell-based studies and imaging modalities. This review aims to give an overview of the current pathophysiology hypotheses surrounding CSC in addition to future directions in cellular work from human induced pluripotent stem cell derived choroidal endothelial cells from CSC patients. Furthermore, this review will provide the reader with an update on the clinical aspects of CSC including risk factors, diagnostic challenges and findings from multimodal imaging.

Subretinal hyperreflective material in central serous chorioretinopathy

Purpose:

To describe the the appearance and behavior of subretinal hyperreflective material (SHRM) in eyes with central serous chorioretinopathy (CSCR).

Methods:

This retrospective study included 20 eyes of 20 patients with CSCR presenting with SHRM, defined as sub-retinal deposits that appear hyper-reflective on OCT The eyes underwent either laser (15 eyes) or observation (5 eyes). Optical coherence tomography and fundus fluorescein angiography (FFA) characteristics were analyzed at baseline and resolution of neurosensory detachment, which were then co-related with the visual acuity at resolution.

Results:

Improvement in vision was seen in 16 eyes. Ellipsoid zone damage (P = 0.03) and external limiting membrane (ELM) damage (P = 0.000) at resolution; diffuse retinal pigment epithelium (RPE) abnormalities on FFA (P = 0.04), and the presence of scar (P = 0.000), were associated with poor visual outcome in univariate analysis. ELM damage at resolution was statistically significant (P = 0.001) in multivariate analysis.

Conclusion:

CSCR with SHRM have a good visual prognosis. ELM damage at resolution corelates with a poor visual acuity at resolution.

Current Choroidal Imaging Findings in Central Serous Chorioretinopathy

Background: Central serous chorioretinopathy (CSCR) is a chorioretinal disease affecting mostly middle age males. It is marked by the serous detachment of the neurosensory layer at the macula. This review of the literature provides a framework of the current characteristic/relevant imaging findings of CSCR. Although the pathogenesis of CSCR is unclear, the choroid plays a major role and its changes are fundamental to the diagnosis and treatment of CSCR. Methods: A systematic literature search focusing on current multimodal imaging for CSCR was performed. Only articles reporting on original clinical data were selected, studies in a language other than English were included only if an English abstract was provided. Additional sources included articles cited in the references list of the first selected articles. We deduced imaging findings based on current and relevant literature on the topic. Results: We found that sub foveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) were greater in eyes with acute CSCR than in eyes with chronic CSCR or normal eyes. There was increased choroidal thickness (CT) in the macula compared to peripapillary region. In healthy eyes, the highest CVI was found in the nasal region followed by the inferior, temporal, and superior quadrant. The area with the least CVI was the macula. In eyes with CSCR, 100% had asymmetric dominant vortex veins compared to 38% in normal eyes. Conclusion: Choroidal imaging has advanced the diagnosis of CSCR. This has led to numerous imaging biomarkers like CVI, CT, and hyper-reflective dots for early detection and possible prognostication of CSCR. More techniques like wide field scans and en face imaging are being employed to characterize the choroid in CSCR.

Protein Composition of the Subretinal Fluid Suggests Selective Diffusion of Vitreous Proteins in Retinal Detachment

Purpose

To study the proteome of the subretinal fluid (SRF) from rhegmatogenous retinal detachment (RRD) in search for novel markers for improved diagnosis and prognosis of RRD.

Methods

Human undiluted SRF obtained during vitrectomy for primary RRD using a 41-gauge needle (n = 24) was analyzed and compared to vitreous humor from 2-day postmortem eyes (n = 20). Sample preparation underwent nanoflow liquid chromatography–tandem mass spectrometry. Label-free quantification (LFQ) using MaxQuant was used to determine differentially expressed proteins between SRF and vitreous humor. The intensity-based absolute quantification (iBAQ) was used to rank proteins according to their molar fractions within groups. Identification of proteins beyond the quantitative level was performed using the Mascot search engine.

Results

The protein concentration of the control vitreous humor was lower and more consistent (1.2 ± 0.4 mg) than that of the SRF (17.9 ± 22 mg). The iBAQ analysis showed high resemblance between SRF and vitreous humor, except for crystallins solely identified in vitreous humor. The LFQ analysis found 38 protein misregulations between SRF and vitreous humor of which the blood coagulation pathway was found to be enriched using the PANTHER Classification System. Combined, the iBAQ, LFQ, and Mascot analysis found an overlap only in chitinase-3-like protein 1 and galectin-3-binding protein unique to the SRF.

Conclusions

The proteome of the SRF was highly represented by proteins involved in proteolysis. Such proteins can possibly serve as targets in modulating the effects of SRF in RD.

Translational Relevance

To identify potential novel biomarkers for therapeutic targeting in RD.

Bullous Central Serous Chorioretinopathy: A Rare and Atypical Form of Central Serous Chorioretinopathy. A Systematic Review

Bullous central serous chorioretinopathy (bCSCR) is a rare variant of the central serous chorioretinopathy, complicated by an exudative retinal detachment with shifting fluid. This systematic review aims to present the epidemiology, the pathogenesis, the clinical presentation, the imaging, the differential diagnosis, and the latest treatments of this disease. A total of 60 studies were identified following a literature search adhering to PRISMA guidelines. After full-text evaluation, 34 studies about bCSCR were included. bCSCR usually affects middle-aged men, and the principal risk factor is corticosteroid medications. Pathogenesis is related to an increased choroidal vessel and choriocapillaris permeability, with subsequent subretinal fluid accumulation, rich in fibrin, which may provoke the exudative retinal detachment. Clinical presentation and imaging are fundamental to distinguish bCSCR from other pathologies, avoiding unappropriated treatment. Corticosteroid withdraws (if assumed) and laser photocoagulation of leakage sites seen at angiography may speed up retinal reattachment. Verteporfin photodynamic therapy, transpupillary thermal therapy, oral eplerenone and scleral thinning surgery are other therapeutic options. An early diagnosis might prevent disease progression due to harmful medications as well as unnecessary surgery.

Review: The bile acids urso- and tauroursodeoxycholic acid as neuroprotective therapies in retinal disease

Bile acids are produced in the liver and excreted into the intestine, where their main function is to participate in lipid digestion. Ursodeoxycholic acid (UDCA) and tauroursodeoxycholic acid (TUDCA) have shown antiapoptotic, anti-inflammatory, and antioxidant effects in various models of neurodegenerative diseases. However, little is known about signaling pathways and molecular mechanisms through which these bile acids act as neuroprotectors, delaying translation to the clinical setting. We review evidence supporting a potentially therapeutic role for bile acids in retinal disorders, and the mechanisms and pathways involved in the cytoprotective effects of bile acids from the liver and the enterohepatic circulation to the central nervous system and the retina. As secondary bile acids are generated by the microbiota metabolism, bile acids might be a link between neurodegenerative retinal diseases and microbiota.

Peripheral retinal avascularity and capillary leakage in central serous chorioretinopathy

Purpose

To report a novel finding of peripheral retinal avascularity (PRA) and peripheral capillary leakage (PCL) on wide-field fluorescein angiography (WFA) in non-dependent quadrants, in eyes with bilateral chronic central serous chorioretinopathy (CSCR).

Methods

Forty six patients with bilateral CSCR were studied. Four patients had PRA and PCL, and 42 patients did not. The demographic profile, clinical findings, and imaging characteristics of the two groups were compared.

Results

There was no significant difference between those patients with and without PRA and PCL with respect to the demographic profile, clinical findings, and imaging characteristics. Laser photocoagulation to extrafoveal points of leakage seen on fluorescein angiography (FA) was sufficient to cause complete resolution of CSCR in these 4 patients. PRA areas were not treated.

Conclusion

The PRA and PCL in CSCR are novel findings, which have not been previously described.

Correlation between preoperative factors and final visual acuity after successful rhegmatogenous retinal reattachment

We evaluated the preoperative optical coherence tomographic (OCT) findings in eyes with macula-off rhegmatogenous retinal detachment (RRD) and determined the factors that were significantly correlated with the postoperative best-corrected visual acuity (BCVA). The length of the preoperative photoreceptors was defined as the distance between the external limiting membrane (ELM) and the outer end of the outer segments of the photoreceptors in the OCT images. The mean length of the photoreceptors was 102.8 ± 28.7 µm with a range of 20 to 159 µm in eyes with RRD. The length of the preoperative photoreceptors was not significantly correlated with the preoperative BCVA but it was significantly correlated with the postoperative BCVA (r = -0.353, P = 0.003). Multivariate regression analyses revealed that the length of the photoreceptors (β = -0.388, P = 0.001) and the preoperative BCVA (β = 0.274, P = 0.021) were the only independent factors that were significantly associated with the postoperative BCVA. The length of the preoperative photoreceptors was significantly correlated with the postoperative photoreceptor length (r = 0.486, P < 0.001). Longer preoperative photoreceptors were significantly correlated with longer postoperative photoreceptors and better BCVA after successful reattachment. These results suggest that the preoperative length of the photoreceptors can be good factor to use for predicting the final BCVA following successful reattachment of macula-off RRD.

Metabolomics and Age-Related Macular Degeneration

Age-related macular degeneration (AMD) leads to irreversible visual loss, therefore, early intervention is desirable, but due to its multifactorial nature, diagnosis of early disease might be challenging. Identification of early markers for disease development and progression is key for disease diagnosis. Suitable biomarkers can potentially provide opportunities for clinical intervention at a stage of the disease when irreversible changes are yet to take place. One of the most metabolically active tissues in the human body is the retina, making the use of hypothesis-free techniques, like metabolomics, to measure molecular changes in AMD appealing. Indeed, there is increasing evidence that metabolic dysfunction has an important role in the development and progression of AMD. Therefore, metabolomics appears to be an appropriate platform to investigate disease-associated biomarkers. In this review, we explored what is known about metabolic changes in the retina, in conjunction with the emerging literature in AMD metabolomics research. Methods for metabolic biomarker identification in the eye have also been discussed, including the use of tears, vitreous, and aqueous humor, as well as imaging methods, like fluorescence lifetime imaging, that could be translated into a clinical diagnostic tool with molecular level resolution.

Proteomic Responses Under Cold Stress Reveal Unique Cold Tolerance Mechanisms in the Pacific White Shrimp (Litopenaeus vannamei)

The Pacific white shrimp (Litopenaeus vannamei), one of the most widely cultured shrimp species in the world, often suffers from cold stress. To understand the molecular mechanism of cold tolerance in Pacific white shrimp, we conducted a proteomic analysis on two contrasting shrimp cultivars, namely, cold-tolerant Guihai2 (GH2) and cold-sensitive Guihai1 (GH1), under normal temperature (28°C), under cold stress (16°C), and during recovery to 28°C. In total, 3,349 proteins were identified, among which 2,736 proteins were quantified. Based on gene ontology annotations, differentially expressed proteins largely belonged to biological processes, cellular components, and molecular functions. KEGG pathway annotations indicated that the main changes were observed in the lysosome, ribosomes, and oxidative phosphorylation. Subcellular localization analysis showed a significant increase in proteins present in cytosol, extracellular regions, and mitochondria. Combining enrichment-based clustering analysis and qRT-PCR analysis, we found that glutathione S-transferase, zinc proteinase, m7GpppX diphosphatase, AP2 transcription complex, and zinc-finger transcription factors played a major role in the cold stress response in Pacific white shrimp. Moreover, structure proteins, including different types of lectin and DAPPUDRAFT, were indispensable for cold stress tolerance of the Pacific white shrimp. Results indicate the molecular mechanisms of the Pacific white shrimp in response to cold stress and provide new insight into breeding new cultivars with increased cold tolerance.