MicroRNAs in the Vitreous Humor of Patients with Retinal Detachment and a Different Grading of Proliferative Vitreoretinopathy: A Pilot Study

MicroRNA-152-3p and MicroRNA-196a-5p Are Downregulated When Müller Cells Are Promoted by Components of the Internal Limiting Membrane: Implications for Macular Hole Healing

Müller cells play a critical role in the closure of macular holes, and their proliferation and migration are facilitated by the internal limiting membrane (ILM). Despite the importance of this process, the underlying molecular mechanism remains underexplored. This study investigated the effects of ILM components on the microRNA (miRNA) profile of Müller cells. Rat Müller cells (rMC-1) were cultured with a culture insert and varying concentrations of ILM component coatings, namely, collagen IV, laminin, and fibronectin, and cell migration was assessed by measuring cell-free areas in successive photographs following insert removal. MiRNAs were then extracted from these cells and analyzed. Mimics and inhibitors of miRNA candidates were transfected into Müller cells, and a cell migration assay and additional cell viability assays were performed. The results revealed that the ILM components promoted Müller cell migration (p < 0.01). Among the miRNA candidates, miR-194-3p was upregulated, whereas miR-125b-1-3p, miR-132-3p, miR-146b-5p, miR-152-3p, miR-196a-5p, miR-542-5p, miR-871-3p, miR-1839-5p, and miR-3573-3p were significantly downregulated (p < 0.05; fold change > 1.5). Moreover, miR-152-3p and miR-196a-5p reduced cell migration (p < 0.05) and proliferation (p < 0.001), and their suppressive effects were reversed by their respective inhibitors. In conclusion, miRNAs were regulated in ILM component-activated Müller cells, with miR-152-3p and miR-196a-5p regulating Müller cell migration and proliferation. These results serve as a basis for understanding the molecular healing process of macular holes and identifying potential new target genes in future research.

Detection of microRNAs expression signatures in vitreous humor of intraocular tuberculosis

BACKGROUND

MicroRNA (miRNA) expression analysis has been shown to provide them as biomarkers in several eye diseases and has a regulatory role in pathogenesis. However, miRNA expression analysis in the vitreous humor (VH) of intraocular tuberculosis (IOTB) is not studied. Thus, we aim to find miRNA expression signatures in the VH of IOTB patients to identify their regulatory role in disease pathogenesis and to find them as potential biomarkers for IOTB.

METHODS AND RESULTS

First, we profiled miRNAs in VH of three IOTB and three Macular hole (MH) samples as controls through small-RNA deep sequencing using Illumina Platform. In-house bioinformatics analysis identified 81 dysregulated miRNAs in IOTB. Further validation in VH of IOTB (n = 15) compared to MH (n = 15) using Real-Time quantitative PCR (RT-qPCR) identified three significantly upregulated miRNAs, hsa-miR-150-5p, hsa-miR-26b-5p, and hsa-miR-21-5p. Based on the miRNA target prediction, functional network analysis, and RT-qPCR analysis of target genes, the three miRNAs downregulating WNT5A, PRKCA, MAP3K7, IL7, TGFB2, IL1A, PRKCB, TNFA, and TP53 genes involving MAPK signaling pathway, PI3K-AKT signaling pathway, WNT signaling pathway, Cell cycle, TGF-beta signaling pathway, Long-term potentiation, and Sphingolipid signaling pathways, have a potential role in disease pathogenesis. The ROC analysis of RT-qPCR data showed that hsa-miR-150-5p with AUC = 0.715, hsa-miR-21-5p with AUC = 0.789, and hsa-miR-26b-5p with AUC = 0.738; however, the combination of hsa-miR-21-5p and hsa-miR-26b-5p with AUC = 0.796 could serve as a potential biomarker for IOTB.

CONCLUSIONS

This study provides the first report on miRNA expression signatures detected in VH for IOTB pathogenesis and also provides a potential biomarker for IOTB.

Proliferative Vitreoretinopathy: A Reappraisal

Proliferative vitreoretinopathy (PVR) remains the main cause of failure after retinal detachment (RD) surgery. Despite the development of modern technologies and sophisticated techniques for the management of RD, the growth of fibrocellular membranes within the vitreous cavity and on both sides of the retinal surface, as well as intraretinal fibrosis, can compromise surgical outcomes. Since 1983, when the term PVR was coined by the Retina Society, a lot of knowledge has been obtained about the physiopathology and risk factors of PVR, but, despite the proposal of a lot of therapeutic challenges, surgical skills seem to be the only effective way to manage PVR complications.

MicroRNA Expression in Subretinal Fluid in Eyes Affected by Rhegmatogenous Retinal Detachment

Proliferative vitreoretinopathy (PVR) is an abnormal intraocular scarring process that can complicate cases of rhegmatogenous retinal detachment (RRD). Although previous studies have examined the relevance of microRNAs (miRNAs) in ophthalmic diseases, only a few studies have evaluated the expression profiles of microRNAs in subretinal fluid. We hypothesized that the expression profiles of specific miRNAs may change in response to RRD, in the subretinal fluid that is directly in contact with photoreceptors and the retinal pigment epithelium (RPE). We looked for a potential correlation between the expression of specific miRNAs in eyes with RRD and known clinical risk factors of PVR. A total of 24 patients (59 ± 11 years) who underwent scleral buckling procedure were enrolled in this prospective study. Twenty-four undiluted subretinal fluid samples were collected, RNA was isolated and qRT-PCR was performed to analyze the expression of 12 miRNAs. We found the existence of a positive association between the expression of miR-21 (p = 0.017, r = 0.515) and miR-34 (p = 0.030, r = 0.624) and the duration of symptoms related to retinal detachment. Moreover, the expression of miR-146a tended to decrease in patients who developed PVR. Subretinal fluid constitutes an intriguing biological matrix to evaluate the role of miRNAs leading to the development of PVR.

Cell Sources for Retinal Regeneration: Implication for Data Translation in Biomedicine of the Eye

The main degenerative diseases of the retina include macular degeneration, proliferative vitreoretinopathy, retinitis pigmentosa, and glaucoma. Novel approaches for treating retinal diseases are based on cell replacement therapy using a variety of exogenous stem cells. An alternative and complementary approach is the potential use of retinal regeneration cell sources (RRCSs) containing retinal pigment epithelium, ciliary body, Müller glia, and retinal ciliary region. RRCSs in lower vertebrates in vivo and in mammals mostly in vitro are able to proliferate and exhibit gene expression and epigenetic characteristics typical for neural/retinal cell progenitors. Here, we review research on the factors controlling the RRCSs' properties, such as the cell microenvironment, growth factors, cytokines, hormones, etc., that determine the regenerative responses and alterations underlying the RRCS-associated pathologies. We also discuss how the current data on molecular features and regulatory mechanisms of RRCSs could be translated in retinal biomedicine with a special focus on (1) attempts to obtain retinal neurons de novo both in vivo and in vitro to replace damaged retinal cells; and (2) investigations of the key molecular networks stimulating regenerative responses and preventing RRCS-related pathologies.

Let-7 as a Promising Target in Aging and Aging-Related Diseases: A Promise or a Pledge

The abnormal regulation and expression of microRNA (miRNA) are closely related to the aging process and the occurrence and development of aging-related diseases. Lethal-7 (let-7) was discovered in Caenorhabditis elegans (C. elegans) and plays an important role in development by regulating cell fate regulators. Accumulating evidence has shown that let-7 is elevated in aging tissues and participates in multiple pathways that regulate the aging process, including affecting tissue stem cell function, body metabolism, and various aging-related diseases (ARDs). Moreover, recent studies have found that let-7 plays an important role in the senescence of B cells, suggesting that let-7 may also participate in the aging process by regulating immune function. Therefore, these studies show the diversity and complexity of let-7 expression and regulatory functions during aging. In this review, we provide a detailed overview of let-7 expression regulation as well as its role in different tissue aging and aging-related diseases, which may provide new ideas for enriching the complex expression regulation mechanism and pathobiological function of let-7 in aging and related diseases and ultimately provide help for the development of new therapeutic strategies.

Mitochondrial RNAs as Potential Biomarkers of Functional Impairment in Diabetic Kidney Disease

Type 2 diabetes and renal damage are strictly linked. The progressive increase in T2D incidence has stimulated the interest in novel biomarkers to improve the diagnostic performance of the commonly utilized markers such as albuminuria and eGFR. Through microarray method, we analyzed the entire transcriptome expressed in 12 serum samples of diabetic patients, six without DKD and six with DKD; the downregulation of the most dysregulated transcripts was validated in a wider cohort of 69 patients by qPCRs. We identified a total of 33 downregulated transcripts. The downregulation of four mitochondrial messenger RNAs (MT-ATP6, MT-ATP8, MT-COX3, MT-ND1) and other two transcripts (seysnoy, skerdo) was validated in patients with eGFR stage G3 versus G2 and G1. The four messenger RNAs correlated with creatinine and eGFR stages, while seysnoy and skerdo were associated with white blood cell values. All transcripts correlated also with Blood Urea Nitrogen. The four mitochondrial messenger RNAs had a high diagnostic performance in G3 versus G2 discrimination, with AUC values above 0.8. The most performant transcript was MT-ATP6, with an AUC of 0.846; sensitivity = 90%, specificity = 76%, p-value = 7.8 × 10⁻⁵. This study led to the identification of a specific molecular signature of DKD, proposing the dosage of RNAs, especially mitochondrial RNAs, as noninvasive biomarkers of diabetes complication.

The Role of Dysregulated miRNAs in the Pathogenesis, Diagnosis and Treatment of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is an eye disease causing damage to the macular region of the retina where most of the photoreceptors responsible for central visual acuity are located. MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that negatively regulate genes by silent post-transcriptional gene expressions. Previous studies have shown that changes in specific miRNAs are involved in the pathogenesis of eye diseases, including AMD. Altered expressions of miRNAs are related to disturbances of regulating oxidative stress, inflammation, angiogenesis, apoptosis and phagocytosis, which are known factors in the pathogenesis of AMD. Moreover, dysregulation of miRNA is involved in drusen formation. Thus, miRNAs may be used as potential molecular biomarkers for the disease and, furthermore, tailoring therapeutics to particular disturbances in miRNAs may, in the future, offer hope to prevent irreversible vision loss. In this review, we clarify the current state of knowledge about the influence of miRNA on the pathogenesis, diagnosis and treatment of AMD. Our study material consisted of publications, which were found in PubMed, Google Scholar and Embase databases using “Age-related macular degeneration”, “miRNA”, “AMD biomarkers”, “miRNA therapeutics” and “AMD pathogenesis” as keywords. Paper search was limited to articles published from 2011 to date. In the section “Retinal, circulating and vitreous body miRNAs found in human studies”, we limited the search to studies with patients published in 2016–2021.

Evaluation of Ab externo subretinal bands removal during pars plana vitrectomy for rhegmatogenous retinal detachment complicated by proliferative vitreoretinopathy

Background

To compare the safety and efficacy of Ab-externo subretinal bands removal in comparison with the classical Ab-interno approach during pars plana vitrectomy for primary rhegmatogenous retinal detachment.

Methods

Subjects aged 28–62 years with primary RRD complicated by proliferative vitreoretinopathy (PVR) with subretinal bands interfering with retinal flattening were treated by pars plana vitrectomy (PPV) and silicone oil injection. Subretinal bands were removed using the classical AB interno approach through one or more retinotomies in ten patients (group A) and using AB externo approach in twenty cases (group B). Post-operative follow-up visits occurred at 1 day, 1 week, 1 month, and 3 months, after surgery. The main outcomes were assessment of subretinal bands removal efficacy, documentation of complications, anatomical reattachment rate, and postoperative best-corrected visual acuity (BCVA).

Results

There was no statistically significant difference between both groups regarding patients’ age, gender, lens status, and the onset of retinal detachment. Seventy percent of both groups presented with inferior retinal detachment while ten percent presented with temporal detachments and twenty percent had a total retinal detachment. Both groups had a statistically significant improvement in postoperative visual acuity in comparison with preoperative visual acuity (P = 0.005 for group A and P =  < 0.001 for group B). There was no statistically significant difference between both groups regarding preoperative (P = 0.928) and postoperative (P = 0.185) visual acuity. A higher incidence of complications was reported in group A (40%) in comparison with group B (30%) but this difference was not statistically significant (P = 0.69). More Epimacular membranes were seen postoperatively in group A (30%) in comparison with group B (20%) but again this difference was not statistically significant (P = 0.657). Subretinal hemorrhage was seen in ten percent of cases in both groups. Intraocular pressure was measured in every follow-up of all patients in both groups, no statistically significant difference was found between both groups.

Conclusions

Both techniques are effective and safe to remove subretinal bands with similar outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02449-0.

Emergency Vitrectomies for Retinal Detachment Before and During the Coronavirus Pandemic - A Retrospective Single Centre Analysis

Background While the corona pandemic and the resulting containment measures affect the number of elective surgical procedures, the impact on emergency surgical interventions is less tangible. This analysis quantifies the frequency of emergency vitrectomies for retinal detachment and investigates underlying factors.

Methods Retrospective identification of patients who underwent primary emergency vitrectomies for retinal detachment at the Cantonal Hospital of Lucerne between 01.01.2018 – 31.12.2020. Parameters were collected, including demographics, date of hospitalisation, reported onset of symptoms, pre-operative best corrected visual acuity (BCVA), involvement of the macula, and canton of residence.

Results Overall, a total of 665 patients with 683 eyes underwent emergency surgery for primary retinal detachment in the time span of 01.01.2018 – 31.12.2020. Median monthly number of surgeries was 20. During the first Swiss national lockdown (16.03.2020 – 19.04.2020), a minimum of 9 vitrectomies was recorded in March 2020. A maximum of 36 vitrectomies was conducted in August 2020. The mean age of patients was 61.5 years. Of the 665 patients, 133 (20.0%) were residents of the canton of Ticino. Median pre-operative BCVA was 0.25 over all three years, and no significant reduction in pre-operative BCVA was observed during or after the lockdown. The proportion of eyes with involvement of the macula was 52.2%. In 2018, this proportion (47.6%) was significantly lower than in 2019 and 2020 (Chi ² test, p < 0.001). However, cases with macular involvement in post lockdown months were not more frequent. Median time in days from reported symptom onset to hospitalisation was 5 days. In April 2020, the proportion of patients with > 14 days symptom duration was significantly higher (Chi ² test, p < 0.001). During the lockdown, there was a significant reduction in cases from Ticino. Also, patients from Ticino showed proportionally longer symptom duration after the lockdown.

Conclusion A significant reduction in the number of emergency vitrectomies was observed for the initial period of the coronavirus pandemic. Delayed emergency presentation is not assumed, since there was no increase in severity (i.e. macular involvement) or prolonged symptoms in the months following the lockdown. More protracted symptoms were only observed in patients from Ticino. The initial low numbers were generally made good later in the year.

Pigment Epithelia of the Eye: Cell-Type Conversion in Regeneration and Disease

Pigment epithelial cells (PECs) of the retina (RPE), ciliary body, and iris (IPE) are capable of altering their phenotype. The main pathway of phenotypic switching of eye PECs in vertebrates and humans in vivo and/or in vitro is neural/retinal. Besides, cells of amphibian IPE give rise to the lens and its derivatives, while mammalian and human RPE can be converted along the mesenchymal pathway. The PECs’ capability of conversion in vivo underlies the lens and retinal regeneration in lower vertebrates and retinal diseases such as proliferative vitreoretinopathy and fibrosis in mammals and humans. The present review considers these processes studied in vitro and in vivo in animal models and in humans. The molecular basis of conversion strategies in PECs is elucidated. Being predetermined onto- and phylogenetically, it includes a species-specific molecular context, differential expression of transcription factors, signaling pathways, and epigenomic changes. The accumulated knowledge regarding the mechanisms of PECs phenotypic switching allows the development of approaches to specified conversion for many purposes: obtaining cells for transplantation, creating conditions to stimulate natural regeneration of the retina and the lens, blocking undesirable conversions associated with eye pathology, and finding molecular markers of pathology to be targets of therapy.

The Aflibercept-Induced MicroRNA Profile in the Vitreous of Proliferative Diabetic Retinopathy Patients Detected by Next-Generation Sequencing

Purpose: Vascular endothelial growth factor-A (VEGF-A) is an important pathogenic factor in proliferative diabetic retinopathy (PDR), and aflibercept (Eylea) is one of the widely used anti-VEGF agents. This study investigated the microRNA (miRNA) profiles in the vitreous of 5 idiopathic macular hole patients (non-diabetic controls), 5 untreated PDR patients (no-treatment group), and 5 PDR patients treated with intravitreal aflibercept injection (treatment group).

Methods: Next-generation sequencing was performed to determine the miRNA profiles. Deregulated miRNAs were validated with quantitative real-time PCR (qRT-PCR) in another cohort. The mRNA profile data (GSE160310) of PDR patients were retrieved from the Gene Expression Omnibus (GEO) database. The function of differentially expressed miRNAs and mRNAs was annotated by bioinformatic analysis and literature study.

Results: Twenty-nine miRNAs were significantly dysregulated in the three groups, of which 19,984 target mRNAs were predicted. Hsa-miR-3184-3p, hsa-miR-24-3p, and hsa-miR-197-3p were validated to be remarkably upregulated in no-treatment group versus controls, and significantly downregulated in treatment group versus no-treatment group. In the GSE160310 profile, 204 deregulated protein-coding mRNAs were identified, and finally 179 overlapped mRNAs between the 19,984 target mRNAs and 204 deregulated mRNAs were included for further analysis. Function analysis provided several roles of aflibercept-induced miRNAs, promoting the alternation of drug sensitivity or resistance-related mRNAs, and regulating critical mRNAs involved in angiogenesis and retinal fibrosis.

Conclusion: Hsa-miR-3184-3p, hsa-miR-24-3p, and hsa-miR-197-3p were highly expressed in PDR patients, and intravitreal aflibercept injection could reverse this alteration. Intravitreal aflibercept injection may involve in regulating cell sensitivity or resistance to drug, angiogenesis, and retinal fibrosis.

Do Extracellular RNAs Provide Insight into Uveal Melanoma Biology?

Simple Summary

The study of RNAs in the extracellular environment in physiological and pathological conditions has become a growing field of research with intriguing applications in diagnostics and prognostics. Such extracellular RNAs are passively or actively released by all cells into biological fluids to spread biological signals to other cells. The perturbation of such RNA-based cell-to-cell communications in cancer can be easily identified by molecular analysis of liquid biopsies, even if source cells secreting RNAs are often elusive. In uveal melanoma (UM), extracellular RNAs can be assayed in serum, plasma, and vitreous and aqueous humor. In this review, we explore the possibility that extracellular RNA alterations in UM could partially match with RNA dysregulations observed in tumor tissues and provide information to better understand UM biology.

Abstract

Uveal melanoma (UM) is the most common primary intraocular malignant tumor in adults, showing a high mortality due to metastasis. Although it is considered a rare disease, a growing number of papers have reported altered levels of RNAs (i.e., coding and non-coding RNAs) in cancerous tissues and biological fluids from UM patients. The presence of circulating RNAs, whose dysregulation is associated with UM, paved the way to the possibility of exploiting it for diagnostic and prognostic purposes. However, the biological meaning and the origin of such RNAs in blood and ocular fluids of UM patients remain unexplored. In this review, we report the state of the art of circulating RNAs in UM and debate whether the amount and types of RNAs measured in bodily fluids mirror the RNA alterations from source cancer cells. Based on literature data, extracellular RNAs in UM patients do not represent, with rare exceptions, a snapshot of RNA dysregulations occurring in cancerous tissues, but rather the complex and heterogeneous outcome of a systemic dysfunction, including immune system activity, that modifies the mechanisms of RNA delivery from several cell types.

The impact of the COVID-19 Pandemic on rhegmatogenous retinal detachment treatment patterns

Backgrounds

To describe changes in rhegmatogenous retinal detachment (RRD) surgical procedures in Beijing during the COVID-19 Pandemic.

Methods

A retrospective cohort of RRD patients was analyzed. Patients were divided into the COVID-19 pandemic group and pre-COVID-19 group according to their presentation. The presurgery characteristics, surgical procedures, and surgery outcomes were collected. The potential factors related to the choice of pars plana vitrectomy (PPV) or scleral buckling (SB) were analyzed using logistic regression. The differences in the procedure choice under specific conditions were compared. Surgery outcomes were compared between the two groups.

Results

In the COVID-19 pandemic group, less patients received SB (27.8, 41.3%, p = 0.02) while more patients received PPV (72.2, 58.6%, p = 0.02); in patients who received SB, fewer patients received subretinal fluid drainage (45.4,75.7%, p = 0.01); in patients who received PPV, fewer patients received phacovitrectomy (7.0, 21.0%, p = 0.02). The choice of PPV was related to older age (1.03, p = 0.005), the presence of RRD with choroidal detachment (RRD-CD) (2.92, p = 0.03), pseudophakia (5.0, p = 0.002), retinal breaks located posterior to the equator (4.87, p < 0.001), macular holes (9.76, p = 0.005), and a presurgery visual acuity (VA) less than 0.02 (0.44, p = 0.03). Fewer phakia patients with retinal breaks located posterior to the equator (1/28, 11/30, p = 0.01) and fewer patients with chronic RRD and subretinal strand (1/9, 9/16, p = 0.03) received SB in the COVID-19 pandemic group. There were more patients with improved VA (55.7, 40.2%, p = 0.03) in the COVID-19 pandemic group. The overall single-surgery retinal attachment rate was similar in the two groups (94.9, 94.5%, p = 0.99).

Conclusions

During the COVID-19 Pandemic, the main reason for the increased number of PPV in RRD treatment was that more complicated cases were presented. However, the surgeons were conservative in procedure choice in specific cases. The adjustments on RRD treatments lead to comparable surgery outcomes.

Characteristics of retinal detachment associated with atopic dermatitis

BACKGROUND

To examine the characteristics of rhegmatous retinal detachment (RRD) associated with atopic dermatitis.

METHOD

Medical records of 2257 patients who underwent RD surgery at this clinic between 2008 and 2018 were retrospectively reviewed. Among them, 61 patients who were diagnosed as AD were assigned into the experimental group and 100 patients who did not have AD were randomly selected and assigned into the control group. Demographics, characteristics of detachment, initial operative method, and prognosis after surgery were investigated as main outcomes. Additionally, in pseudophakic RD patients, the period between the cataract surgery and onset of RD was measured.

RESULT

Postoperative VA and prognosis were significantly worse and bilateral involvement of RD was more common in the atopy group than in the control group. (P value = 0.005, 0.001 each) Characteristics of retinal breaks were different between the two groups. Additionally, the risk of developing RD within 1 year after cataract surgery was significantly higher in pseudophakic patients of the atopic group than in the control group. (P value = 0.013) However, there was no significant difference in mean preoperative VA or refractive index between the two groups.

CONCLUSION

Our results show that in atopic patients, RD occurs at a young age with different characteristics compared to non-atopic patients. Atopic RD has a poor visual prognosis. Thus, it requires careful management. Furthermore, the risk of developing RD within 1 year after cataract surgery is higher in atopic patients. Therefore, it is important to perform regular and extensive check-up after cataract surgery for atopic patients.

New Therapeutic Perspectives in the Treatment of Uveal Melanoma: A Systematic Review

Uveal melanoma (UM) is a rare disease, but the most common primary intraocular cancer, mostly localized in the choroid. Currently, the first-line treatment options for UM are radiation therapy, resection, and enucleation. However, although these treatments could potentially be curative, half of all patients will develop metastatic disease, whose prognosis is still poor. Indeed, effective therapeutic options for patients with advanced or metastatic disease are still lacking. Recently, the development of new treatment modalities with a lower incidence of adverse events, a better disease control rate, and new therapeutic approaches, have merged as new potential and promising therapeutic strategies. Additionally, several clinical trials are ongoing to find new therapeutic options, mainly for those with metastatic disease. Many interventions are still in the preliminary phases of clinical development, being investigated in phase I trial or phase I/II. The success of these trials could be crucial for changing the prognosis of patients with advanced/metastatic UM. In this systematic review, we analyzed all emerging and available literature on the new perspectives in the treatment of UM and patient outcomes; furthermore, their current limitations and more common adverse events are summarized.

Biomarkers for Nonexudative Age-Related Macular Degeneration and Relevance for Clinical Trials: A Systematic Review

TOPIC

The purpose of the review was to identify structural, functional, blood-based, and other types of biomarkers for early, intermediate, and late nonexudative stages of age-related macular degeneration (AMD) and summarize the relevant data for proof-of-concept clinical trials.

CLINICAL RELEVANCE

AMD is a leading cause of blindness in the aging population, yet no treatments exist for its most common nonexudative form. There are limited data on the diagnosis and progression of nonexudative AMD compared to neovascular AMD. Our objective was to provide a comprehensive, systematic review of recently published biomarkers (molecular, structural, and functional) for early AMD, intermediate AMD, and geographic atrophy and to evaluate the relevance of these biomarkers for use in future clinical trials.

METHODS

A literature search of PubMed, ScienceDirect, EMBASE, and Web of Science from January 1, 1996 to November 30, 2020 and a patent search were conducted. Search terms included "early AMD," "dry AMD," "intermediate AMD," "biomarkers for nonexudative AMD," "fundus autofluorescence patterns," "color fundus photography," "dark adaptation," and "microperimetry." Articles were assessed for bias and quality with the Mixed-Methods Appraisal Tool. A total of 94 articles were included (61,842 individuals).

RESULTS

Spectral-domain optical coherence tomography was superior at highlighting detailed structural changes in earlier stages of AMD. Fundus autofluorescence patterns were found to be most important in estimating progression of geographic atrophy. Delayed rod intercept time on dark adaptation was the most widely recommended surrogate functional endpoint for early AMD, while retinal sensitivity on microperimetry was most relevant for intermediate AMD. Combinational studies accounting for various patient characteristics and machine/deep-learning approaches were best suited for assessing individualized risk of AMD onset and progression.

CONCLUSION

This systematic review supports the use of structural and functional biomarkers in early AMD and intermediate AMD, which are more reproducible and less invasive than the other classes of biomarkers described. The use of deep learning and combinational algorithms will gain increasing importance in future clinical trials of nonexudative AMD.

Investigation of MicroRNA Expression in Anterior Lens Capsules of Senile Cataract Patients and MicroRNA Differences According to the Cataract Type

Purpose

We investigated the microRNAs (miRNAs) expression in the anterior lens capsules of patients with senile cataract and compared it to that in the anterior lens capsules of healthy controls. Moreover, we compared the differences in miRNAs expression according to the types of cataracts.

Methods

Individual lens epithelium samples were collected from 33 senile patients and 10 controls. The cataract patients were classified into cortical, nuclear, posterior and anterior subcapsular and mixed. The expression of 12 different miRNAs in lens epithelium was measured using real-time polymerase chain reaction and compared between the senile cataract patients and controls. The differences of miRNA levels according to cataract type were analyzed.

Results

The expression levels of let-7g-5p, miR-23a-3p, miR-23b-3p, and miR-125a-5p were significantly upregulated in patients with senile cataract when compared with those in the control group (P < 0.05). The expressions of let-7a-5p, let-7d-5p, miR-16-5p and miR-22-3p were significantly downregulated in the senile cataracts (P < 0.05). Let-7a-5p, let-7d-5p, let-7g-5p and mir-23b-3p had significant difference in expression between nuclear and anterior subcapsular cataracts.

Conclusions

The eight differentially expressed miRNAs may be involved in the pathogenesis of senile cataract, in particular, related to oxidative stress and autophagy.

Translational Relevance

We infer that several miRNAs in lens epithelial cells are promising candidate biomarkers of senile cataracts.

miRNAs and Genes Involved in the Interplay between Ocular Hypertension and Primary Open-Angle Glaucoma. Oxidative Stress, Inflammation, and Apoptosis Networks

Glaucoma has no cure and is a sight-threatening neurodegenerative disease affecting more than 100 million people worldwide, with primary open angle glaucoma (POAG) being the most globally prevalent glaucoma clinical type. Regulation of gene expression and gene networks, and its multifactorial pathways involved in glaucoma disease are landmarks for ophthalmic research. MicroRNAs (miRNAs/miRs) are small endogenous non-coding, single-stranded RNA molecules (18–22 nucleotides) that regulate gene expression. An analytical, observational, case-control study was performed in 42 patients of both sexes, aged 50 to 80 years, which were classified according to: (1) suffering from ocular hypertension (OHT) but no glaucomatous neurodegeneration (ND) such as the OHT group, or (2) have been diagnosed of POAG such as the POAG group. Participants were interviewed for obtaining sociodemographic and personal/familial records, clinically examined, and their tear samples were collected and frozen at 80 °C until processing for molecular-genetic assays. Tear RNA extraction, libraries construction, and next generation sequencing were performed. Here, we demonstrated, for the first time, the differential expression profiling of eight miRNAs when comparing tears from the OHT versus the POAG groups: the miR-26b-5p, miR-152-3p, miR-30e-5p, miR-125b-2-5p, miR-224-5p, miR-151a-3p, miR-1307-3p, and the miR-27a-3p. Gene information was set up from the DIANA-TarBase v7, DIANA-microT-CDS, and TargetScan v7.1 databases. To build a network of metabolic pathways, only genes appearing in at least four of the following databases: DisGeNet, GeneDistiller, MalaCards, OMIM PCAN, UniProt, and GO were considered. We propose miRNAs and their target genes/signaling pathways as candidates for a better understanding of the molecular-genetic bases of glaucoma and, in this way, to gain knowledge to achieve optimal diagnosis strategies for properly identifying HTO at higher risk of glaucoma ND. Further research is needed to validate these miRNAs to discern the potential role as biomarkers involved in oxidative stress, immune response, and apoptosis for the diagnosis and/or prognosis of OHT and the prevention of glaucoma ND.

Antioxidant Status in the Vitreous of Eyes with Rhegmatogenous Retinal Detachment with and without Proliferative Vitreoretinopathy, Macular Hole and Epiretinal Membrane

(1) Background: The aim of the study was to test the hypothesis that the antioxidant status in the vitreous body of eyes, which had been vitrectomized due to rhegmatogenous retinal detachment (RRD) with or without proliferative vitreoretinopathy (PVR), is higher than in eyes vitrectomized due to other retinal diseases. (2) Methods: four patient groups were analyzed: 22 eyes of patients with RRD without PVR, 27 eyes with RRD and PVR, 22 eyes with macular hole (MH) and 10 eyes with epiretinal membrane (ERM). Spectrophotometric methods were used to determine the total antioxidant status (TAS) values as well as superoxide dismutase (SOD) and glutathione reductase (GR) activities in the vitreous fluid samples. (3) Results: no significant differences in TAS values and antioxidant enzyme activities were observed among patient with RRD with and without PVR and with MH and ERM. The longer the duration of RRD leading to PVR and better postoperative visual acuity, the higher the TAS level. No significant differences were found between "macula on" and "macula off" subgroups within the RRD group and the RRD combined with PVR group. (4) Conclusions: The preliminary results do not support the thesis that the antioxidant status of vitrectomized eyes is different in patients with RRD with or without PVR in comparison to patients with MH and ERM. In patients with RRD, PVR presence and detached macula do not affect the values of TAS, SOD and GR in the vitreous fluid. The duration of the disease influences TAS in the vitreous in eyes with RRD complicated with PVR.

The risk factors of the progression of rhegmatogenous retinal detachment on patients with the fourteen-day quarantine in the early period of COVID-19 outbreak

Backgrounds

The COVID-19 Pandemic has a great impact on hospitals and patients. The 14-day quarantine caused surgery of rhegmatogenous retinal detachment (RRD) postponed. We aimed to explore the risk factors of RRD progression in a group of patients whose surgery was postponed during the top-level emergency response of COVID-19.

Methods

A retrospective case series. Medical records of all consecutive patients with a diagnosis of RRD who underwent a surgical treatment at Beijing Tongren Hospital’s retina service from February 16, 2020, to April 30, 2020 have been reviewed retrospectively. Medical history, symptoms, and clinical signs of progression of RRD were recorded. RRD progression was defined as the presence of either choroidal detachment or proliferative vitreoretinopathy (PVR) progression during the quarantine period. Risk factors were analyzed using the Cox proportional hazards model, survival analysis, and logistic regression.

Results

Seventy-nine eyes of 79 patients met the inclusion criteria and were included in the study. The median time from the patients’ presentation at the clinic to admission for surgery was 14 days (3–61 days). There were 70 cases (88.6%) who did not present to the hospital within 1 week of the onset of visual symptoms. There were 69 (87.3%) macular-off cases at the presentation and 27 (34.2%) cases combined with choroidal detachment. There were 49 (62.0%) cases with PVR B, 22 (27.8%) cases with PVR C, 4 (5.1%) cases with PVR D, and 4 (5.1%) cases with anterior PVR. After the 14-day quarantine, 21 (26.6%) cases showed RRD progression, and 9 cases showed RRD regression at the time of surgery. Neither the time of onset of the visual symptom (p = 0.46) nor the time between presentation and admission (p = 0.31) was significantly different between the patients with RRD progression and patients without RRD progression. The combination of choroidal detachment (3.07, 1.68-5.60, p<0.001) and retinal breaks located posterior to the equator (3.79, 1.21-11.80, p=0.02) were factors related to the progression of RRD.

Conclusions

In our study during the COVID-19 outbreak, the RRD progression risk factors included a combination of choroidal detachment and retinal breaks posterior to the equator. Ophthalmologists should schedule the surgeries for RRD patients with these signs as soon as possible.

Characteristics of fixation patterns and their relationship with visual function of patients with idiopathic macular holes after vitrectomy

To analyze the relationships between the fixation location and the visual function of idiopathic macular hole (IMH) patients with macular integrity assessment (MAIA) examination preoperatively and 3 months postoperatively. This was a retrospective case analysis. Forty-three eyes of 43 patients diagnosed with IMH were included in this study. The best corrected visual acuity (BCVA) assessments, optical coherence tomography (OCT) and MAIA examinations were performed before surgery and 1 week, 1 month and 3 months after surgery. The relationships between MAIA parameters and visual acuity were assessed by correlation analysis. Grouping by fixation location with the foveola (2°) as the centre, the locations could be divided into five groups, including foveolar, temporal, nasal, inferior and superior fixation. The mean macular sensitivity (MMS) of the macular area was correlated with the BCVA in the IMH patients before and 3 months after surgery (before surgery P = 0.00, after surgery P = 0.00). The MMS could be used as a good indicator for evaluating visual function in IMH patients. There was a significant difference in fixation location before and after the operation (P = 0.01). The preoperative fixation location of IMH patients was mainly in the superior area, while postoperatively moved to the foveola and nasal areas. Paying attention to the changes of fixation locations in IMH patients may provide new clues for further improving postoperative visual function.

Influences of Central Bouquet Alterations on the Visual Outcome in Eyes Receiving Epiretinal Membrane Surgery

Background: Previous studies have shown that epiretinal membranes (ERMs) may be associated with abnormal outer retinal anatomy. However, long-term morphological and functional results of pars plana vitrectomy (PPV) with ERM and internal limiting membrane (ILM) peeling in eyes with central bouquet (CB) alterations have not yet been investigated. Methods: In a retrospective, consecutive study all patients underwent best corrected visual acuity (BCVA) testing and spectral domain optical coherence tomography (SD-OCT) before and after a mean of 20 months (range 3–70 months) postoperatively. CB abnormalities and ERMs were classified according to Govetto’s staging systems. Results: Of the 67 eyes, 22 (34%) showed CB abnormalities at baseline. The mean BCVA increased from 0.42 at baseline to 0.20 LogMAR at final follow-up (p < 0.001). Neither ERM stage (p = 0.06) nor CB stage (p = 0.939) at baseline were significant predictors of vision improvement following surgery. Conclusions: Our results show that baseline BCVA, but not classification of CB changes and ERM at baseline, seems to be a useful predictor for functional outcomes following PPV with ERM and ILM peeling in the long-term.

Age-related increase of let-7 family microRNA in rat retina and vitreous

Vitreous alterations occur from early stages and continue through the normal aging, with gradual lamellae formation and the appearance of liquefied spaces, which eventually leads to complications, such as retinal tear, retinal detachment, and intravitreal hemorrhage. The aim of the present study was to investigate the expression of let-7 miRNA family in the vitreous and retina in newborn (1-3- day-old), young adult (2-month-old), and aging (12-month-old) rats, as well as their role as regulators of vitreous components. MicroRNAs are small, non-coding RNAs that post-transcriptionally regulate gene expression. Our results showed detection of all investigated let-7 isoforms (let-7a, let-7b, let-7c, let-7d, let-7e, let-7f and let-7i) in the retina and vitreous. Although most let-7 members were significantly upregulated in the vitreous during development, only let-7b, let-7c, and let-7e followed this same expression pattern in the retina. Let-7b and -7c increased in aging vitreous as well, and were expressed in vitro by Müller glial cells and their extracellular vesicles. Moreover, let-7 targeted hyaluronan synthase 2 (Has2) mRNA, a synthesizing enzyme of hyaluronan. These observations indicate that let-7 function is important during retina and vitreous development, and that isoforms of let-7 increased with aging, potentially modulating hyaluronan content.

Interphotoreceptor Retinoid-Binding Protein (IRBP) in Retinal Health and Disease

Interphotoreceptor retinoid-binding protein (IRBP), also known as retinol binding protein 3 (RBP3), is a lipophilic glycoprotein specifically secreted by photoreceptors. Enriched in the interphotoreceptor matrix (IPM) and recycled by the retinal pigment epithelium (RPE), IRBP is essential for the vision of all vertebrates as it facilitates the transfer of retinoids in the visual cycle. It also helps to transport lipids between the RPE and photoreceptors. The thiol-dependent antioxidant activity of IRBP maintains the delicate redox balance in the normal retina. Thus, its dysfunction is suspected to play a role in many retinal diseases. We have reviewed here the latest research on IRBP in both retinal health and disease, including the function and regulation of IRBP under retinal stress in both animal models and the human retina. We have also explored the therapeutic potential of targeting IRBP in retinal diseases. Although some technical barriers remain, it is possible that manipulating the expression of IRBP in the retina will rescue or prevent photoreceptor degeneration in many retinal diseases.