Concise Review: Using Stem Cells to Prevent the Progression of Myopia-A Concept

Characteristics and Prevalence of Staphyloma Edges at Different Ages in Highly Myopic Eyes

Purpose

The purpose of this study was to determine the characteristics of staphyloma edges in highly myopic eyes and how they progress.

Methods

We conducted a cross-sectional analysis using baseline data and a longitudinal study with follow-up data from 256 patients (447 eyes) with high myopia, with a mean (SD) follow-up of 3.79 (0.78) years. Participants were divided into four age groups: children (<13), youth (13-24), mature (25-59), and elderly (>60). Ultrawide-field swept-source optical coherence tomography was used to analyze staphyloma edges, which were divided into four areas: nasal to the optic disc (OD), superior to the macula, inferior to the macula, and temporal to the macula.

Results

Staphylomas were significantly more prevalent in the mature (42.49%) and the elderly (51.35%) groups than in the children (13%) and youth (9%) groups. Staphyloma edges were predominantly superior to the macula in the mature and elderly groups. In contrast, staphylomas were rare in children and youth, with their edges mainly located nasal to the OD. The edges of staphylomas located superior and temporal to the macula were more likely to be associated with myopic traction maculopathy. During the follow-up period, 11 new staphyloma edges developed primarily in the mature group (64%). Additionally, 12 edges had an increased degree of protrusion over time, with most cases occurring in the mature (75%) group.

Conclusions

The prevalence and location of staphyloma edges show significant variations depending on age. As time progresses, staphyloma edges manifest at distinct sites and increase their protrusion, potentially playing a role in the emergence of fundus complications.

Advancements in Ocular Regenerative Therapies

The use of stem cells (SCs) has emerged as a promising avenue in ophthalmology, offering potential therapeutic solutions for various vision impairments and degenerative eye diseases. SCs possess the unique ability to self-renew and differentiate into specialised cell types, making them valuable tools for repairing damaged tissues and restoring visual function. Stem cell-based therapies hold significant potential for addressing conditions such as age-related macular degeneration (AMD), retinitis pigmentosa (RP), corneal disorders, and optic nerve damage. Therefore, researchers have explored different sources of stem cells, including embryonic stem cells (ESC), induced pluripotent stem cells (iPSCs), and adult stem cells, for ocular tissue regeneration. Preclinical studies and early-phase clinical trials have demonstrated promising outcomes, with some patients experiencing improved vision following stem cell-based interventions. However, several challenges remain, including optimising the differentiation protocols, ensuring transplanted cells' safety and long-term viability, and developing effective delivery methods. The field of stem cell research in ophthalmology witnesses a constant influx of new reports and discoveries. To effectively navigate these tons of information, it becomes crucial to summarise and systematise these findings periodically. In light of recent discoveries, this paper demonstrates the potential applications of stem cells in ophthalmology, focusing on their use in various eye tissues, including the cornea, retina, conjunctiva, iris, trabecular meshwork, lens, ciliary body, sclera, and orbital fat.

Ocular Rigidity and Current Therapy

Purpose: Ocular rigidity (OR) is an important biomechanical parameter of the eye accounting for the material and geometrical properties of the corneoscleral shell.Methods: This study used a literature search to review the role of ocular rigidity and the application of potential therapies targeting this parameter in glaucoma and myopia.Conclusion: Biomechanical modeling and improved understanding of the biochemistry, and molecular arrangement of sclera and its constituents have yielded important insights. Recent developments, including that of a non-invasive and direct OR measurement method and improved ocular imaging techniques are helping to elucidate the role of OR in healthy and diseased eyes by facilitating large scale and longitudinal clinical studies. Improved understanding of OR at the initial stages of disease processes and its alterations with disease progression will undoubtedly propel research in the field. Furthermore, a better understanding of the determinants of OR is helping to refine novel therapeutic approaches which target and alter the biomechanical properties of the sclera in sight-threatening conditions such as glaucoma and myopia.

Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute

The prevalence of myopia is increasing extensively worldwide. The number of people with myopia in 2020 is predicted to be 2.6 billion globally, which is expected to rise up to 4.9 billion by 2050, unless preventive actions and interventions are taken. The number of individuals with high myopia is also increasing substantially and pathological myopia is predicted to become the most common cause of irreversible vision impairment and blindness worldwide and also in Europe. These prevalence estimates indicate the importance of reducing the burden of myopia by means of myopia control interventions to prevent myopia onset and to slow down myopia progression. Due to the urgency of the situation, the European Society of Ophthalmology decided to publish this update of the current information and guidance on management of myopia. The pathogenesis and genetics of myopia are also summarized and epidemiology, risk factors, preventive and treatment options are discussed in details.

Review on current concepts of myopia and its control strategies

Myopia poses a significant burden on the healthcare system, economy and quality of life. It is an emerging global public health challenge and requires interventions to delay or stop onset and progression. With changing times and evidence, the concepts of myopia are changing along with the treatment and control strategies. Behavioural modifications including increased outdoors time and reduced near work, optical and pharmaceutical management options are reviewed. This paper presents a current overview on the concepts of myopia, and is expected to summarize updates on myopia control methods.

A prospective study of serum metabolomic and lipidomic changes in myopic children and adolescents

BACKGROUND

Myopia is a prevalent eye disorder, especially among children and adolescents in eastern Asian countries. Multiple measures have already been taken to prevent and treat myopia, including atropine and dopamine. However, the serum metabolic picture of myopia has not yet been studied as a whole and remains largely unclear. In this paper, a prospective and panoramic study was carried out to find out the whole serum metabolomic and lipidomic picture of myopia.

METHODS

With untargeted mass spectrometry (MS), myopia among 211 children and adolescents was studied. The MS features were first grouped across the samples. Then, compound annotation was carried out based on these features. Finally, the metabolite features were mapped to pathways, whose biological functions in myopia were studied and discussed.

RESULTS

A total of 275 metabolite features were derived from 92 aligned MS peak groups with significant fold changes, and then mapped to 33 pathways. By a comprehensive consideration of significance, fold change, importance score and appearance in different omics, 9 pathways were selected, and their biological functions were further analyzed. Among these selected pathways, 5 pathways were related with oxidative stress, a validated phenomenon during myopia development, while 5 pathways were related with dopamine receptor D2, whose molecular function in myopia treatment is not fully understood. A total of 177 metabolite features from 45 peak groups were related with the studied pathways.

CONCLUSION

This prospective study shed light on the whole picture of metabolomic mechanism underlying myopia and provided guidance to further elucidation of compounds and pathways in this whole picture.

Regulatory roles of differentially expressed MicroRNAs in metabolic processes in negative Lens-induced myopia Guinea pigs

BACKGROUND

Myopia is one of the most common vision defects worldwide. microRNAs can regulate the target gene expression, influencing the development of diseases.

RESULTS

To investigate the alterations of microRNA profiling in negative lens-induced myopia (NLIM) guinea pigs and to explore the regulatory role of microRNAs in the occurrence and the development of myopia, we first established the NLIM guinea pig model after induction for 2 weeks. Further, we isolated sclera to purify total messenger RNA (mRNA) in both NLIM and NLIM fellow sclera. Using next generation sequencing technique and bioinformatics analysis, we identified the differentially expressed microRNAs in NLIM guinea pigs, performed the bioinformatics annotation for the differentially expressed microRNAs, and validated the expression of differentially expressed microRNAs. As a result, we successfully established an NLIM model in guinea pigs, identified 27 differentially expressed microRNAs in NLIM guinea pig sclera, including 10 upregulated and 17 downregulated microRNAs. The KEGG annotation showed the main signaling pathways were closely associated with PPAR signaling, pyruvate and propanoate metabolisms, and TGF-beta signaling pathways.

CONCLUSIONS

Our findings indicate that the development of myopia is mainly involved in the disorder of metabolic processes in NLIM guinea pigs. The PPAR signaling, pyruvate and propanoate metabolism pathways may play roles in the development of myopia.

Phakic Posterior Chamber Intraocular Lens with a Central Hole in Treating Patients with Moderate to High Myopia: A Meta-Analysis

Purpose

To evaluate the efficacy of phakic posterior chamber intraocular lens with a central hole (ICL V4c) in treating patients with moderate to high myopia.

Methods

PubMed, Embase, Cochrane Library, Clinical Trial, China Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), and China Science Periodical Database (CSPD) were searched online. The search included publications from the building of the library until December 2018. All randomized controlled trials containing moderate to high myopia treated by phakic posterior chamber intraocular lens with a central hole were collected. Literature search, screening literature, data extraction, and quality evaluation were independently performed by two reviewers. Meta-analysis was performed using RevMan 5.3 software.

Results

Meta-analysis results based on five randomized controlled trials showed that ICL V4c and ICL without a central hole had similar UCVA results (SMD = 0.08, 95% CI (−0.71, 0.88), P=0.84), SE (SMD = −0.18, 95% CI (−0.52, 0.15), P=0.29), BCVA (SMD = −0.27, 95% CI (−0.93, 0.40), P=0.43), and IOP (SMD = 0.03, 95% CI (−0.24, 0.30), P=0.84), and the difference was not statistically significant. In addition, no complications that could jeopardize vision occurred.

Conclusions

Implanting ICL V4c in patients with moderate to high myopia is safe and effective.

Posterior Scleral Reinforcement to Prevent Progression of High Myopia

BACKGROUND

Myopia has become a global public health problem. High myopia is linked to pathologic myopia (PM). As the severity of myopia increases, excessive axial elongation of the globe exerts a biomechanical stretch on the posterior pole, followed by a series of retinopathy which can lead to marked visual impairment. Posterior scleral reinforcement (PSR) is the only way that may have the potential to prevent the progression of axial elongation. Some scholars expressed satisfaction with the efficacy and safety of PSR. In contrast, other surgeons had negative conclusions on the outcomes for the surgery.

OBJECTIVES

The aims of this review are to provide an update on the current knowledge of posterior scleral reinforcement to prevent progression of high myopia and to discuss clinical trials examining the potential utility of PSR in treating this disease.

METHODS

We searched Ovid MEDLINE, Embase, PubMed and China National Knowledge Infrastructure (CNKI) (all years to 1 July 2019). We also conducted a gray literature search and handsearched reference lists of included studies and pertinent review articles.

RESULTS

26 clinical trials were included. 20 trials were designed as only one eye of each patient had posterior scleral reinforcement surgery. After 3 to 5 years of follow-up, the results are very satisfactory. 6 randomized controlled trials, which have conservatively treated groups, showed statistically significant differences between the eyeball axial length progression in the study group and the control group, where surgery was not performed. Most clinical trials reached a positive influence. But the efficacy of different clinical trials varies greatly.

CONCLUSIONS

PSR, is safe and effective to slowdown myopia progression, especially for high myopia.

Scleral structure and biomechanics

As the eye's main load-bearing connective tissue, the sclera is centrally important to vision. In addition to cooperatively maintaining refractive status with the cornea, the sclera must also provide stable mechanical support to vulnerable internal ocular structures such as the retina and optic nerve head. Moreover, it must achieve this under complex, dynamic loading conditions imposed by eye movements and fluid pressures. Recent years have seen significant advances in our knowledge of scleral biomechanics, its modulation with ageing and disease, and their relationship to the hierarchical structure of the collagen-rich scleral extracellular matrix (ECM) and its resident cells. This review focuses on notable recent structural and biomechanical studies, setting their findings in the context of the wider scleral literature. It reviews recent progress in the development of scattering and bioimaging methods to resolve scleral ECM structure at multiple scales. In vivo and ex vivo experimental methods to characterise scleral biomechanics are explored, along with computational techniques that combine structural and biomechanical data to simulate ocular behaviour and extract tissue material properties. Studies into alterations of scleral structure and biomechanics in myopia and glaucoma are presented, and their results reconciled with associated findings on changes in the ageing eye. Finally, new developments in scleral surgery and emerging minimally invasive therapies are highlighted that could offer new hope in the fight against escalating scleral-related vision disorder worldwide.

Myopic maculopathy: Current status and proposal for a new classification and grading system (ATN)

Myopia is a highly frequent ocular disorder worldwide and pathologic myopia is the 4th most common cause of irreversible blindness in developed countries. Pathologic myopia is especially common in East Asian countries. Ocular alterations associated with pathologic myopia, especially those involving the macular area-defined as myopic maculopathy-are the leading causes of vision loss in patients with pathologic myopia. High myopia is defined as the presence of a highly negative refractive error (>-6 to -8 diopters) in the context of eye elongation (26-26.5 mm). Although the terms high myopia and pathologic myopia are often used interchangeably, they do not refer to the same eye disease. The two key factors driving the development of pathologic myopia are: 1) elongation of the axial length and 2) posterior staphyloma. The presence of posterior staphyloma, which is the most common finding in patients with pathologic myopia, is the key differentiating factor between high and pathologic myopia. The occurrence of staphyloma will, in most cases, eventually lead to other conditions such as atrophic, traction, or neovascular maculopathy. Posterior staphyloma is for instance, responsible for the differences between a myopic macular hole (MH)-with and without retinal detachment-and idiopathic MH. Posterior staphyloma typically induces retinal layer splitting, leading to foveoschisis in myopic MH, an important differentiating factor between myopic and emmetropic MH. Myopic maculopathy is a highly complex disease and current classification systems do not fully account for the numerous changes that occur in the macula of these patients. Therefore, a more comprehensive classification system is needed, for several important reasons. First, to more precisely define the disease stage to improve follow-up by enabling clinicians to more accurately monitor changes over time, which is essential given the progressive nature of this condition. Second, unification of the currently-available classification systems would establish standardized classification criteria that could be used to compare the findings from international multicentric studies. Finally, a more comprehensive classification system could help to improve our understanding of the genetic origins of this disease, which is clearly relevant given the interchangeable-but erroneous-use of the terms high and pathologic myopia in genetic research.

Efficacy and Adverse Effects of Atropine in Childhood Myopia: A Meta-analysis

Importance

Some uncertainty about the clinical value and dosing of atropine for the treatment of myopia in children remains.

Objective

To evaluate the efficacy vs the adverse effects of various doses of atropine in the therapy for myopia in children.

Data Sources

Data were obtained from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials, from inception to April 30, 2016. The reference lists of published reviews and clinicaltrials.gov were searched for additional relevant studies. Key search terms included myopia, refractive errors, and atropine. Only studies published in English were included.

Study Selection

Randomized clinical trials and cohort studies that enrolled patients younger than 18 years with myopia who received atropine in at least 1 treatment arm and that reported the annual rate of myopia progression and/or any adverse effects of atropine therapy were included in the analysis.

Data Extraction and Synthesis

Two reviewers independently abstracted the data. Heterogeneity was statistically quantified by Q, H, and I2 statistics, and a meta-analysis was performed using the random-effects model. The Cochrane Collaboration 6 aspects of bias and the Newcastle-Ottawa Scale were used to assess the risk for bias.

Main Outcomes and Measures

The primary outcome was a difference in efficacy and the presence of adverse effects at different doses of atropine vs control conditions. The secondary outcomes included the differences in adverse effects between Asian and white patients.

Results

Nineteen unique studies involving 3137 unique children were included in the analysis. The weighted mean differences between the atropine and control groups in myopia progression were 0.50 diopters (D) per year (95% CI, 0.24-0.76 D per year) for low-dose atropine, 0.57 D per year (95% CI, 0.43-0.71 D per year) for moderate-dose atropine, and 0.62 D per year (95% CI, 0.45-0.79 D per year) for high-dose atropine (P < .001), which translated to a high effect size (Cohen d, 0.97, 1.76, and 1.94, respectively). All doses of atropine, therefore, were equally beneficial with respect to myopia progression (P = .15). High-dose atropine were associated with more adverse effects, such as the 43.1% incidence of photophobia compared with 6.3% for low-dose atropine and 17.8% for moderate-dose atropine (χ22 = 7.05; P = .03). In addition, differences in the incidence of adverse effects between Asian and white patients were not identified (χ21 = 0.81; P = .37 for photophobia).

Conclusions and Relevance

This meta-analysis suggests that the efficacy of atropine is dose independent within this range, whereas the adverse effects are dose dependent.

Bio-environmental factors associated with myopia: An updated review

Experimental studies in animals, as well as observational and intervention studies in humans, seem to support the premise that the development of juvenile myopia is promoted by a combination of the effect of genetic and environmental factors, with a complex interaction between them. The very rapid increase in myopia rates in some parts of the world, such as Southeast Asia, supports a significant environmental effect. Several lines of evidence suggest that humans might respond to various external factors, such as increased activity in near vision, increased educational pressure, decreased exposure to sunlight outdoors, dietary changes (including increased intake of carbohydrates), as well as low light levels indoors. All these factors could be associated with a higher prevalence of myopia.

Rasgrf1 mRNA expression in myopic eyes of guinea pigs

BACKGROUND

Genome-wide association studies of patients have linked the Rasgrf1 gene with myopia. The aim of this study was to investigate the messenger RNA (mRNA) expression of Rasgrf1 in the eyes of guinea pigs with induced myopia.

METHODS

The myopia was induced by form deprivation in 24 guinea pigs, while additional 12 animals served as a control. Biometric measurements were used to monitor myopic progression. The animals were sacrificed at two, three and four weeks after beginning of the monocular form deprivation, followed by dissection of the retina, and the sclera, as well as mRNA isolation from both layers. A quantitative reverse transcriptase-polymerase chain reaction was performed to detect the expression of Rasgrf1.

RESULTS

The spherical equivalent in eyes subjected to form deprivation differed from the fellow eyes, with measurements of -3.80 ± 0.08 D, -3.96 ± 0.94 D and -4.00 ± 0.94 D at the two-, three- and four-week times, respectively, significantly more myopia than the inter-ocular difference in the control group (p < 0.05). The form-deprived eyes also had a longer axial length compared with the fellow eye: 1.37 ± 0.76 mm, 1.32 ± 0.65 mm and 0.92 ± 0.80 mm at two, three and four weeks, respectively, significantly different from the control group (p < 0.05). In contrast, there was no difference in the corneal curvature, anterior chamber depth or lens thickness between the two eyes at any time (p > 0.05). The increase of Rasgrf1 expression was observed in the sclera, with a fold change of 6.596, 4.379 after three weeks and 6.788, 5.711 after four weeks of treatment, compared with the fellow eyes and the control group, respectively (p < 0.05).

CONCLUSION

Rasgrf1 up-regulation was found in the sclera of myopic eyes; however, further investigation is needed to determine whether Rasgrf1 plays a causative role or is a consequence of myopia-induced scleral remodelling.

Effect of MRI tags: SPIO nanoparticles and 19F nanoemulsion on various populations of mouse mesenchymal stem cells

Transplantation of mesenchymal stem cells (MSCs) has emerged as a promising strategy for the treatment of myriad human disorders, including several neurological diseases. Superparamagnetic iron oxide nanoparticles (SPION) and fluorine nanoemulsion (19F) are characterized by low toxicity and good sensitivity, and, as such, are among the most frequently used cell-labeling agents. However, to date, their impact across the various populations of MSCs has not been comprehensively investigated. Thus, the impact of MRI tags (independent variable) has been set as a primary endpoint. The various populations of mouse MSCs in which the effect of tag was investigated consisted of (1) tissue of cell origin: bone marrow vs. Adipose tissue; (2) age of donor: young vs. old; (3) cell culture conditions: hypoxic vs. normal vs. normal + ascorbic acid (AA); (4) exposure to acidosis: yes vs. no. The impact of those populations has been also analyzed and considered as secondary endpoints. The experimental readouts (dependent variables) included: (1) cell viability; (2) cell size; (3) cell doubling time; (4) colony formation; (5) efficiency of labeling; and (6) cell migration. We did not identify any impact of cell labeling for these investigated populations in any of the readouts. In addition, we found that the harsh microenvironment of injured tissue modeled by a culture of cells in a highly acidic environment has a profound effect on all readouts, and both age of donor and cell origin tissue also have a substantial influence on most of the readouts, while oxygen tension in the cell culture conditions has a smaller impact on MSCs. A detailed characterization of the factors that influence the quality of MSCs is vital to the proper pursuit of preclinical and clinical studies.