The influence of the choroid on the onset and development of myopia: from perspectives of choroidal thickness and blood flow

Techniques for imaging the choroid and choroidal blood flow in vivo

The choroid, which is a highly vascularized layer between the retina and sclera, is essential for supplying oxygen and nutrients to the outer retina. Choroidal vascular dysfunction has been implicated in numerous ocular diseases, including age-related macular degeneration, central serous chorioretinopathy, polypoidal choroidal vasculopathy, and myopia. Traditionally, the in vivo assessment of choroidal blood flow relies on techniques such as laser Doppler flowmetry, laser speckle flowgraphy, pneumotonometry, laser interferometry, and ultrasonic color Doppler imaging. While the aforementioned methods have provided valuable insights into choroidal blood flow regulation, their clinical applications have been limited. Recent advancements in optical coherence tomography and optical coherence tomography angiography have expanded our understanding of the choroid, allowing detailed visualization of the larger choroidal vessels and choriocapillaris, respectively. This review provides an overview of the available techniques that can investigate the choroid and its blood flow in vivo. Future research should combine these techniques to comprehensively image the entire choroidal microcirculation and develop robust methods to quantify choroidal blood flow. The potential findings will provide a better picture of choroidal hemodynamics and its effect on ocular health and disease.

Melanopsin in the human and chicken choroid

The choroid embedded in between retina and sclera is essential for retinal photoreceptor nourishment, but is also a source of growth factors in the process of emmetropization that converts retinal visual signals into scleral growth signals. Still, the exact control mechanisms behind those functions are enigmatic while circadian rhythms are involved. These rhythms are attributed to daylight influences that are melanopsin (OPN4) driven. Recently, OPN4-mRNA has been detected in the choroid, and while its origin is unknown we here seek to identify the underlying structures using morphological methods. Human and chicken choroids were prepared for single- and double-immunohistochemistry of OPN4, vasoactive intestinal peptide (VIP), substance P (SP), CD68, and α-smooth muscle actin (ASMA). For documentation, light-, fluorescence-, and confocal laser scanning microscopy was applied. Retinal controls proved the reliability of the OPN4 antibody in both species. In humans, OPN4 immunoreactivity (OPN4-IR) was detected in nerve fibers of the choroid and adjacent ciliary nerve fibers. OPN4+ choroidal nerve fibers lacked VIP, but were co-localized with SP. OPN4-immunoreactivity was further detected in VIP+/SP + intrinsic choroidal neurons, in a hitherto unclassified CD68-negative choroidal cell population thus not representing macrophages, as well as in a subset of choroidal melanocytes. In chicken, choroidal nerve fibers were OPN4+, and further OPN4-IR was detected in clustered suprachoroidal structures that were not co-localized with ASMA and therefore do not represent non-vascular smooth-muscle cells. In the choroidal stroma, numerous cells displayed OPN4-IR, the majority of which was VIP-, while a few of those co-localized with VIP and were therefore classified as avian intrinsic choroidal neurons. OPN4-immunoreactivity was absent in choroidal blood vessels of both species. In summary, OPN4-IR was detected in both species in nerve fibers and cells, some of which could be identified (ICN, melanocytes in human), while others could not be classified yet. Nevertheless, the OPN4+ structures described here might be involved in developmental, light-, thermally-driven or nociceptive mechanisms, as known from other systems, but with respect to choroidal control this needs to be proven in upcoming studies.

Lactylome analysis reveals potential target modified proteins in the retina of form-deprivation myopia

The biological mechanisms underlying the development of myopia have not yet been completely elucidated. The retina is critical for visual signal processing, which primarily utilizes aerobic glycolysis to produce lactate as a metabolic end product. Lactate facilitates lysine lactylation (Kla), a posttranslational modification essential for transcriptional regulation. This study found increased glycolytic flux and lactate accumulation in the retinas of form-deprived myopic guinea pigs. Subsequently, a comprehensive analysis of Kla levels in retinal proteins revealed that Kla was upregulated at 124 sites in 92 proteins and downregulated at three sites in three proteins. Functional enrichment and protein interaction analyses showed significant enrichment in pathways related to energy metabolism, including glutathione metabolism, glycolysis, and the hypoxia-inducible factor-1 signaling pathway. Parallel-reaction monitoring confirmed data reliability. These findings suggest a connection between myopia and retinal energy metabolism imbalance, providing new insights into the pathogenesis of myopia.

Air pollutant exposure is associated with visual trajectories and visual impairment in children

Air pollution is associated with vision loss in children, but the relationship with vision trajectories has not been explored. The study was conducted as a prospective cohort in 16 districts of Shanghai from 2021 to 2023, involving 5612 children with complete survey data. Each child underwent 3-4 eye tests, including unaided visual acuity and computerized refraction. Children's air pollutant exposure levels (PM2.5, PM10, O3, SO2, NO2, and CO) were assessed using school addresses and examination dates. Latent class mixture modeling was used to identify the trajectories of changes in vision-related measurements in children. Multinomial logistic regression and Cox proportional hazards regression were used to examine the association of air pollutant exposure and visual trajectories, as well as visual impairment outcomes. The study identified three trajectory categories for children's unaided visual acuity, spherical equivalent, and four trajectory categories for axial length. Increased levels of PM2.5, PM10, O3, and SO2 exposure are associated with an increased risk of categorizing vision-related measurements into the "poor" category trajectory in children. Increased exposure to PM2.5, O3, and NO2 was associated with an increased risk of visual impairment outcomes in children with normal vision at baseline, and the effect was more significant in female and older children.

Effects of 2 Hz flickering light on refractive state, fundus imaging and visual function of C57BL/6 mice

In this study, we investigated the effects of flickering light on refractive development of mice and the changes of fundus structure and function during this process. C57BL/6 mice were randomly divided into control group and flickering light-induced myopia (FLM) group. Mice in the control group were fed under normal lighting. FLM group mice were fed under lighting with a duty cycle of 50% and flash frequency of 2 Hz. Refractive status, axial length (AL), corneal radius of curvature (CRC), and electroretinogram signals were measured in all animals before treatment and at 2 and 4 weeks after treatment. Retinal thickness (RT), choroidal thickness (ChT) and choroidal blood perfusion (ChBP) were measured by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). After 4 weeks of flickering light stimulation, the mice became myopia, the AL increased, but the CRC remained constant. The induction of myopia reduced the implicit time and amplitude of a-wave and b-wave in electroretinogram, which affects the function of retina. Full-layer retinal thickness, ChT and ChBP decreased at both 2 and 4 weeks after flickering light induction. The superficial and middle layers of the retina were significantly thinner, while the deep layer was only slightly thinner without statistical significance. Calculated by the concentric circle algorithm, the decrease of choroidal blood perfusion in FLM was mainly concentrated in the concentric circle area with the optic disc as the center radius of 150-450 μm. In conclusion, the present study shows that flickering light can successfully induce myopia in C57BL/6 mice, affect the electrophysiological activity of retina, and cause changes in fundus tissue structure and blood flow.

Factors affecting choroidal circulation parameters in 4-14-year-old Chinese children measured by SS-OCT/OCTA

PURPOSE

To measure the choroidal circulatory parameters Han Chinese children aged 4-14 years from Southwest China, and to explore the relationships between these parameters and age, axial length (AL), and choroidal thickness (ChT).

METHODS

284 eyes from 142 subjects were included in this cross-sectional study. All participants underwent cycloplegic refraction and IOLMaster500 examination. Swept-source optical coherence tomography (SS-OCT) was used to measure submacular choroidal thickness, choroidal vascular volume (CVV), choroidal stromal volume (CSV), choroidal vascularity index (CVI), and CVV/CSV ratio.

RESULTS

In this population, the mean CVV was 2.92 ± 0.55 mm3, CSV was 4.69 ± 0.68 mm3, CVI was 38.22 ± 2.46 %, and CVV/CSV ratio was 62.11 ± 6.44 %. Multivariable regression analyses showed that both CVV and CSV were negatively correlated with AL (both P < 0.001) and positively correlated with ChT (both P < 0.001), while age showed no significant correlation with them (both P > 0.05). However, the correlations between CVI and age were not uniform rectilinear. Among participants aged ≤8 years, CVI showed no correlation with age (P > 0.05), while among those aged >8 years, it was positively correlated with age (P < 0.01). CVV/CSV ratio was positively correlated with ChT and age (both P < 0.01).

CONCLUSION

After the age of 8, age was positively correlated with CVI. ChT was well correlated with CVI. Longer AL and thinner ChT were associated with reduced CVV and CSV, with CVV decreasing more rapidly than CSV.

Choroidal thinning in myopia is associated with axial elongation and severity of myopic maculopathy

High myopia can lead to pathologic myopia and visual impairment, whereas its causes are unclear. We retrospectively researched high myopia cases from patient records to investigate the association between axial elongation and myopic maculopathy. Sixty-four eyes were examined in patients who visited the department between July 2017 and June 2018, had an axial length of 26 mm or more, underwent fundus photography, and had their axial length measured twice or more. The average axial length was 28.29 ± 1.69 mm (mean ± standard deviation). The average age was 58.3 ± 14.4 years old. Myopic maculopathy was categorized as mild (grades 0 and 1) and severe (grades 2, 3, and 4). The severe group had longer axial lengths than the mild group (P < 0.05). Moreover, the severe group exhibited thinner choroidal thickness than the mild group (P < 0.05). When subjects were grouped by axial elongation over median value within a year, the elongation group showed thinner central choroidal thickness than the non-elongation group (142.1 ± 91.9 vs. 82.9 ± 69.8, P < 0.05). In conclusion, in patients with high myopia, the severity of maculopathy correlated with choroidal thickness and axial length. Thinner choroidal thickness was associated with axial elongation based on the baseline axial length.

Diurnal gene expression patterns in retina and choroid distinguish myopia progression from myopia onset

The world-wide prevalence of myopia (nearsightedness) is increasing, but its pathogenesis is incompletely understood. Among many putative mechanisms, laboratory and clinical findings have implicated circadian biology in the etiology of myopia. Consistent with a circadian hypothesis, we recently reported a marked variability in diurnal patterns of gene expression in two crucial tissues controlling post-natal refractive development - the retina and choroid-at the onset of form-deprivation myopia in chick, a widely studied and validated model. To extend these observations, we assayed gene expression by RNA-Seq in retina and choroid during the progression of established unilateral form-deprivation myopia of chick. We assayed gene expression every 4 hours during a single day from myopic and contralateral control eyes. Retinal and choroidal gene expression in myopic vs. control eyes during myopia progression differed strikingly at discrete times during the day. Very few differentially expressed genes occurred at more than one time in either tissue during progressing myopia. Similarly, Gene Set Enrichment Analysis pathways varied markedly by time during the day. Some of the differentially expressed genes in progressing myopia coincided with candidate genes for human myopia, but only partially corresponded with genes previously identified at myopia onset. Considering other laboratory findings and human genetics and epidemiology, these results further link circadian biology to the pathogenesis of myopia; but they also point to important mechanistic differences between the onset of myopia and the progression of established myopia. Future laboratory and clinical investigations should systematically incorporate circadian mechanisms in studying the etiology of myopia and in seeking more effective treatments to normalize eye growth in children.

Short-term effects of sunlight exposure on fundus blood flow perfusion in children: a randomised controlled trial

AIM

To evaluate the short-term effects of different sunlight exposure on fundus blood flow perfusion (BFP) after near work.

METHODS

In this parallel randomised controlled trial, 81 students aged 7-15 with spherical equivalent refraction between -2.00 and +3.00 diopters were randomly assigned to either a low-illuminance (4k lux) group (N=40) or high-illuminance (10k lux) (N=41). Following 1 hour indoor reading, participants had sunlight exposure matching their group's intensity for 15 minutes. BFPs in the superficial retina, deep retina and choroid were measured at four time points: pre-reading, post-reading, 5th-minute and 15th-minute sunlight exposure.

RESULTS

Within the initial 5 minutes of sunlight exposure, the 10k lux group showed a tendency for decreased BFP, particularly in the choroid (superficial retina: -0.2, 95% CI -0.9 to 0.5; deep retina: -0.1, 95% CI -0.6 to 0.4; choroid: -0.4, 95% CI -0.8 to 0.0), while the 4k lux group exhibited an increase (superficial retina: 0.7, 95% CI 0.1 to 1.3; deep retina: 0.3, 95% CI -0.2 to 0.8; choroid: 0.1, 95% CI -0.2 to 0.5). From 5 to 15 minutes, BFP decreased in both groups. At the 5th-minute mark, the 10k lux group exhibited a greater decrease in choroid (10k -0.4 vs 4k 0.1, p=0.051). No significant difference was observed after 15 minutes of exposure.

CONCLUSION

Higher illuminance sunlight exposure can restore fundus BFP more rapidly than lower; however, duration remains pivotal. To prevent myopia, continuous sunlight exposure for over 15 minutes is recommended to aid in reinstating the fundus BFP increased by near work.

TRIAL REGISTRATION NUMBER

NCT05594732.

Effects of Acute Mental Stress on Choroidal Thickness

Purpose: Previous studies have indicated an association between education and myopia, suggesting that numerous stress events during the educational process may influence eye health. This study aimed to investigate the impact of mental stress induced by mental arithmetic (MA) on choroidal thickness (CT). Methods: This study included 33 participants aged between 19 and 29 years. Swept-source optical coherence tomography (SS-OCT) was used to capture images of the posterior segment of the left eye during baseline and MA to assess changes in the CT. After denoising and compensation, the baseline images and MA images that had been rigidly registered and resampled to the baseline images were segmented using a deep learning-based method. Based on the segmentation results, the CT within the regions of 1 mm and 3 mm diameter centered at the lowest point of the fovea was calculated. Results: Significant increases were observed in both CT1mm and CT3mm during MA, with mean changes of 2.742 ± 7.098 μm (p = 0.034) and 3.326 ± 6.143 μm (p < 0.001), respectively. Conclusions: Thickening of the choroid has been observed during acute mental stress. We speculate that long-term or chronic mental stress could have a potential adverse impact on myopia progression.

Computational modelling of scleral photocrosslinking: from rat to minipig to human

Selective scleral crosslinking has been proposed as a novel treatment to increase scleral stiffness to counteract biomechanical changes associated with glaucoma and high myopia. Scleral stiffening has been shown by transpupillary peripapillary scleral photocrosslinking in rats, where the photosensitizer, methylene blue (MB), was injected retrobulbarly and red light initiated crosslinking reactions with collagen. Here, we adapted a computational model previously developed to model this treatment in rat eyes to additionally model MB photocrosslinking in minipigs and humans. Increased tissue length and subsequent diffusion and light penetration limitations were found to be barriers to achieving the same extent of crosslinking as in rats. Per cent inspired O2, injected MB concentration and laser fluence were simultaneously varied to overcome these limitations and used to determine optimal combinations of treatment parameters in rats, minipigs and humans. Increasing these three treatment parameters simultaneously resulted in maximum crosslinking, except in rats, where the highest MB concentrations decreased crosslinking. Additionally, the kinetics and diffusion of photocrosslinking reaction intermediates and unproductive side products were modelled across space and time. The model provides a mechanistic understanding of MB photocrosslinking in scleral tissue and a basis for adapting and screening treatment parameters in larger animal models and, eventually, human eyes.

The association between screen time exposure and myopia in children and adolescents: a meta-analysis

OBJECTIVE

This study aimed to systematically review epidemiological evidence on associations between screen time exposure and myopia in children and adolescents, and to quantitatively evaluate summary effect estimates from existing literature.

METHOD

There were three online databases including PubMed, Embase, and Web of Science, for epidemiological studies on screen time exposure and myopia published before June 1, 2023. The risk of bias was assessed by the Newcastle Ottawa Scale (NOS) checklist. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the correlation between screen time exposure and myopia using random or fixed-effect models by exposure type (categorical/continuous). We also performed subgroup analysis by screen device type, study quality, geographic region, and research period.

RESULTS

We searched 7,571 records from three databases and identified 19 eligible studies, including 14 high-quality studies and 5 moderate-quality studies. Meta-analyses suggested that there was a statistically significant correlation between screen time (high vs. low) and myopia. The pooled ORs with 95%CIs were respectively 2.24 (1.47-3.42) for cross-sectional studies, and 2.39 (2.07-2.76) for cohort studies. We also found a significant association between continuous exposure to screen time (per 1 h/d increase) and myopia in cohort studies. The pooled ORs with 95%CIs were 1.07 (1.01-1.13). In subgroup analysis stratified by screen device type in cross-sectional studies, screen time exposures from computers (categorical: OR = 8.19, 95%CI: 4.78-14.04; continuous: OR = 1.22, 95%CI: 1.10-1.35) and televisions (categorical: OR = 1.46, 95%CI: 1.02-2.10) were associated with myopia, while smartphones were not. Although publication bias was detected, the pooled results did not show significant changes after adjustment using the trim and fill method.

CONCLUSION

Our findings support that screen time exposure was significantly associated with myopia in children and adolescents. Notably, screen time exposure from computers may have the most significant impact on myopia.

Innate immune responsive inflammation in development of progressive myopia

PURPOSE

Inflammation has been implicated for development of myopia. It is not clear when inflammation is kicked in during the course of myopia, and what characteristics of the inflammation. In this study, we tested for cytokines from aqueous humour of eyes with wide spectrum of refractive status for profiling the inflammation.

METHODS

Aqueous humour of 142 patient eyes were tested for soluble intercellular adhesion molecule 1 (sICAM-1), monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-beta 2 (TGF-β2) using an enzyme-linked immunosorbent assay (ELISA). Eye globe axial length of these patients ranged from emmetropia to high myopia.

RESULTS

Of 142 patients, an average axial length is 25.51 ± 3.31 mm, with a range of 21.56-34.37 mm. There are 36 cases in lower 25 percentile, 37 cases in upper 25 percentile, and 69 case in the middle 50 percentile. sICAM-1 and MCP-1 were significantly higher in the eyes with staphyloma (407.48 pg/mL, 312.31 pg/mL, n = 33) or macular schisis (445.86 pg/mL,345.33 pg/mL, n = 19) than that in the eyes without these changes (206.44 pg/mL, 244.76 pg/mL, n = 107). All three cytokines level was significantly associated with eye globe axial in a positive mode while adjusting for the age and sex. Strength of the association was the greatest for sICAM-1 and the weakest for TGF- β2. MCP-1 was in between.

CONCLUSION

sICAM-1 and MCP-1 in ocular fluid may be indicative biomarkers for progressive high myopia and the underneath autoimmune inflammation. sICAM-1 may be used as a monitoring biomarker for development of pathologic myopia.

Myopia Is an Ischemic Eye Condition: A Review from the Perspective of Choroidal Blood Flow

Myopia is a common refractive error that affects a large proportion of the population. Recent studies have revealed that alterations in choroidal thickness (ChT) and choroidal blood flow (ChBF) play important roles in the progression of myopia. Reduced ChBF could affect scleral cellular matrix remodeling, which leads to axial elongation and further myopia progression. As ChT and ChBF could be used as potential biomarkers for the progression of myopia, several recent myopia treatments have targeted alterations in ChT and ChBF. Our review provides a comprehensive overview of the recent literature review on the relationship between ChBF and myopia. We also highlight the importance of ChT and ChBF in the progression of myopia and the potential of ChT as an important biomarker for myopia progression. This summary has significant implications for the development of novel strategies for preventing and treating myopia.

Eye Diseases: When the Solution Comes from Plant Alkaloids

Plants are an incredible source of metabolites showing a wide range of biological activities. Among these, there are the alkaloids, which have been exploited for medical purposes since ancient times. Nowadays, many plant-derived alkaloids are the main components of drugs used as therapy for different human diseases. This review deals with providing an overview of the alkaloids used to treat eye diseases, describing the historical outline, the plants from which they are extracted, and the clinical and molecular data supporting their therapeutic activity. Among the different alkaloids that have found application in medicine so far, atropine and pilocarpine are the most characterized ones. Conversely, caffeine and berberine have been proposed for the treatment of different eye disorders, but further studies are still necessary to fully understand their clinical value. Lastly, the alkaloid used for managing hypertension, reserpine, has been recently identified as a potential drug for ameliorating retinal disorders. Other important aspects discussed in this review are different solutions for alkaloid production. Given that the industrial production of many of the plant-derived alkaloids still relies on extraction from plants, and the chemical synthesis can be highly expensive and poorly efficient, alternative methods need to be found. Biotechnologies offer a multitude of possibilities to overcome these issues, spanning from genetic engineering to synthetic biology for microorganisms and bioreactors for plant cell cultures. However, further efforts are needed to completely satisfy the pharmaceutical demand.

Assessment of the effects of myopic and hyperopic anisometropia on choroidal vascular structure in children using SS-OCTA

OBJECTIVE

To compare large- and medium-sized choroidal vascularity and the choriocapillaris (CC) flow area in children with different refractive errors using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

Forty-two anisometropic children were enrolled and divided into hyperopic anisometropia (HA) and myopic anisometropia (MA) groups. SS-OCTA was performed to analyse choroidal vascularity. Mean choroidal thickness (CT), choroidal vascularity volume (CVV), choroidal vascularity index (CVI) and CC flow area were compared between the two eyes. The inter-ocular differences between the two groups were also determined.

RESULTS

Mean CT and CVV were highest in eyes with shorter axial lengths in both refractive groups, and the difference between the two eyes was positively correlated with the difference in axial length at the foveal region. Significant differences in the CVI in the MA group were only found in the parafoveal region. Inter-ocular differences in the CC were significantly reduced in eyes with longer axial lengths in the foveal and parafoveal regions of the HA and MA groups, respectively. Comparing inter-ocular differences, CC was significantly greater in the parafoveal region of the MA group than the HA group.

CONCLUSIONS

All layers of choroidal vasculature were thinner in eyes with longer axial lengths in all groups. The inter-ocular CC difference was greater in the MA than in the HA group, with similar differences in axial length. This suggests that both medium-to-large choroidal vascular and choroidal capillaries may play a role in myopia development.

Variations in choroidal thickness between emmetropic and myopic eyes after caffeine intake

PURPOSE

To investigate the variations in choroidal thinning between emmetropic and myopic subjects after caffeine intake.

METHODS

Forty-five healthy participants (age mean ± standard deviation [SD]: 20.75 ± 1.6 years) recruited in a prospective cross-sectional study. They were divided into three groups, based on refractive error status, emmetropes (spherical equivalent [SE] -0.25 to +0.25D), myopes (SE ≥-0.50D to ˂-6.00D), and high myopes (SE ≥-6.00D). The participants underwent choroidal thickness [ChT] measurements using optical coherence tomography [OCT] (Topcon 3D OCT-1 Maestro System) at baseline, 20, 40, and 60 minutes after consuming 200 mg of caffeine. The measurements of ChT were taken from five different areas horizontally.

RESULTS

Compared to baseline measurement, the ChT significantly decreased after 200 mg caffeine intake in all conditions ( P < 0.001). There was a statistically significant difference in ChT at baseline between the refractive groups ( χ2 (2)=6.548, P = 0.038) as the high myope group showed lesser horizontal ChT within Nasal at (1 mm) area compared to the myope group ( P = 0.032), however, no other significant differences in mean scores of horizontal ChT at baseline were found. The thinning in ChT in the high myope group was lesser compared to both emmetrope and myope groups; however, it was not statistically significant ( P > 0.05).

CONCLUSION

The results of this study suggest that the reduction in ChT due to caffeine consumption is not significantly affected by the refractive status of the eye. Thus, it is safe to hypothesize that the vascular part of the choroid behaves identically to vasoconstrictive in both emmetropic and myopic eyes. The choroidal thinning found in myopic and high myopic eyes and/or the reduced choroidal vascularity index were not apparent in this study. Therefore, further longitudinal studies recruiting greater numbers of participants, including myopes and high myopes, and measuring both vascular and stromal layers to investigate such variations are warranted.

Glutathione and a Pool of Metabolites Partly Related to Oxidative Stress Are Associated with Low and High Myopia in an Altered Bioenergetic Environment

Oxidative stress forms part of the molecular basis contributing to the development and manifestation of myopia, a refractive error with associated pathology that is increasingly prevalent worldwide and that subsequently leads to an upsurge in degenerative visual impairment due to conditions that are especially associated with high myopia. The purpose of our study was to examine the interrelation of potential oxidative-stress-related metabolites found in the aqueous humor of high-myopic, low-myopic, and non-myopic patients within a clinical study. We conducted a cross-sectional study, selecting two sets of patients undergoing cataract surgery. The first set, which was used to analyze metabolites through an NMR assay, comprised 116 patients. A total of 59 metabolites were assigned and quantified. The PLS-DA score plot clearly showed a separation with minimal overlap between the HM and control samples. The PLS-DA model allowed us to determine 31 major metabolite differences in the aqueous humor of the study groups. Complementary statistical analysis of the data allowed us to determine six metabolites that presented significant differences among the experimental groups (p < 005). A significant number of these metabolites were discovered to have a direct or indirect connection to oxidative stress linked with conditions of myopic eyes. Notably, we identified metabolites associated with bioenergetic pathways and metabolites that have undergone methylation, along with choline and its derivatives. The second set consisted of 73 patients who underwent a glutathione assay. Here, we showed significant variations in both reduced and oxidized glutathione in aqueous humor among all patient groups (p < 0.01) for the first time. Axial length, refractive status, and complete ophthalmologic examination were also recorded, and interrelations among metabolic and clinical parameters were evaluated.

Aging in Ocular Blood Vessels: Molecular Insights and the Role of Oxidative Stress

Acknowledged as a significant pathogenetic driver for numerous diseases, aging has become a focal point in addressing the profound changes associated with increasing human life expectancy, posing a critical concern for global public health. Emerging evidence suggests that factors influencing vascular aging extend their impact to choroidal and retinal blood vessels. The objective of this work is to provide a comprehensive overview of the impact of vascular aging on ocular blood vessels and related diseases. Additionally, this study aims to illuminate molecular insights contributing to vascular cell aging, with a particular emphasis on the choroid and retina. Moreover, innovative molecular targets operating within the domain of ocular vascular aging are presented and discussed.

Optical coherence tomography in children with inherited retinal disease

Recent advances have led to therapeutic options becoming available for people with inherited retinal disease. In particular, gene therapy has been shown to hold great promise for slowing vision loss from inherited retinal disease. Recent studies suggest that gene therapy is likely to be most effective when implemented early in the disease process, making consideration of paediatric populations important. It is therefore necessary to have a comprehensive understanding of retinal imaging in children with inherited retinal diseases, in order to monitor disease progression and to determine which early retinal biomarkers may be used as outcome measures in future clinical trials. In addition, as many optometrists will review children with an inherited retinal disease, an understanding of the expected imaging outcomes can improve clinical care. This review focuses on the most common imaging modality used in research assessment of paediatric inherited retinal diseases: optical coherence tomography. Optical coherence tomography findings can be used in both the clinical and research setting. In particular, the review discusses current knowledge of optical coherence tomography findings in eight paediatric inherited retinal diseases - Stargardt disease, Bests disease, Leber's congenital amaurosis, choroideremia, RPGR related retinitis pigmentosa, Usher syndrome, X-linked retinoschisis and, Batten disease.

Short-term effects of cyclopentolate and tropicamide eye drops on macular choroidal thickness in myopic children

BACKGROUND

To investigate the short-term effects of cyclopentolate and tropicamide eyedrops on choroidal thickness (ChT) in myopic children using placebo or low-dose atropine eyedrops.

METHODS

The analysis included 242 myopic individuals (7-19 years) enrolled in two randomised placebo-controlled clinical trials of low-dose atropine eyedrops. Cycloplegia was induced using either one drop of 1% cyclopentolate (n = 161), two drops of 1% cyclopentolate (n = 32) or two drops of 1% tropicamide (n = 49). ChT measurements were taken using swept-source optical coherence tomography before and 30 min after administering the cycloplegic eye drops. A subset of 51 participants underwent test-retest measurements prior to cycloplegia.

RESULTS

Mean changes in subfoveal ChT after two drops of tropicamide and one and two drops of cyclopentolate were -2.5 μm (p = 0.10), -4.3 μm (p < 0.001) and -9.6 μm (p < 0.001), respectively. Subfoveal ChT changes after one and two drops of cyclopentolate were significantly greater than the test-retest changes (test-retest mean change: -3.1 μm; p < 0.05), while the tropicamide group was not significantly different (p = 0.64). Choroidal thinning post-cyclopentolate was not significantly different between atropine and placebo treatment groups (p > 0.05 for all macular locations). The coefficient of repeatability (CoR) in the tropicamide group (range: 8.2-14.4 μm) was similar to test-retest (range: 7.5-12.2 μm), whereas greater CoR values were observed in the cyclopentolate groups (one drop: range: 10.8-15.3 μm; two drops: range: 12.2-24.6 μm).

CONCLUSIONS

Cyclopentolate eye drops caused dose-dependent choroidal thinning and increased variation in pre- to post-cycloplegia measurements compared with test-retest variability, whereas tropicamide did not. These findings have practical implications for ChT measurements when cyclopentolate is used, particularly for successive measurements.

Human Pluripotent Stem Cells Derived Endothelial Cells Repair Choroidal Ischemia

Choroidal atrophy is a common fundus pathological change closely related to the development of age-related macular degeneration (AMD), retinitis pigmentosa, and pathological myopia. Studies suggest that choroidal endothelial cells (CECs) that form the choriocapillaris vessels are the first cells lost in choroidal atrophy. It is found that endothelial cells derived from human pluripotent stem cells (hPSC-ECs) through the MESP1+ mesodermal progenitor stage express CECs-specific markers and can integrate into choriocapillaris. Single-cell RNA-seq (scRNA-seq) studies show that hPSC-ECs upregulate angiogenesis and immune-modulatory and neural protective genes after interacting with ex vivo ischemic choroid. In a rat model of choroidal ischemia (CI), transplantation of hPSC-ECs into the suprachoroidal space increases choroid thickness and vasculature density. Close-up examination shows that engrafted hPSC-ECs integrate with all layers of rat choroidal vessels and last 90 days. Remarkably, EC transplantation improves the visual function of CI rats. The work demonstrates that hPSC-ECs can be used to repair choroidal ischemia in the animal model, which may lead to a new therapy to alleviate choroidal atrophy implicated in dry AMD, pathological myopia, and other ocular diseases.

Comparative Proteomic Analysis of Aqueous Humor Reveals Biochemical Disparities in the Eyes of High Myopic Patients

Myopia accounts for a significant proportion of visual lesions worldwide and has the potential to progress toward pathological myopia. This study aims to reveal the difference in protein content in aqueous humor between high myopic and nonhigh myopic patients, as well as better understand the dysregulation of proteins in myopic eyes. Aqueous humor was collected for liquid chromatograph mass spectrometer (LC/MS) analysis from 30 individual eyes that underwent phacoemulsification and intraocular lens (IOL) implantation. Results showed that a total of 190 differentially expressed proteins were identified, which revealed their involvement in cell metabolism, immune and inflammatory response, and system and anatomical structure. Further analysis focused on 15 intensively interacted hub proteins, encompassing functions related to complement cascades, lipoprotein metabolism, and fibrin biological function. Subsequent validations demonstrated elevated levels of APOE (apolipoprotein E), C3 (complement 3), and AHSG (α-2-HS-glycoprotein) in the high myopia group (31 eyes of cataracts and 45 eyes of high myopia with cataracts). AHSG had a significant positive correlation with axial length in high myopic patients, with good efficacy in distinguishing between myopic and nonmyopic groups. AHSG may be a potential indicator of the pathological severity and participator in the pathological progress of high myopia. This study depicted differential expression characteristics of aqueous humor in patients with high myopia and provided optional information for further experimental research on exploring the molecular mechanisms and potential therapeutic targets for high myopia. Data are available via ProteomeXchange with the identifier PXD047584.

Metabolomic profiling of ocular tissues in rabbit myopia: Uncovering differential metabolites and pathways

To investigate the metabolic difference among tissue layers of the rabbits' eye during the development of myopia using metabolomic techniques and explore any metabolic links or cascades within the ocular wall. Ultra Performance Liquid Chromatography - Mass Spectrometry (UPLC-MS) was utilized for untargeted metabolite screening (UMS) to identify the significant differential metabolites produced between myopia (MY) and control (CT) (horizontal). Subsequently, we compared those key metabolites among tissues (Sclera, Choroid, Retina) of MY for distribution and variation (longitudinal). A total of 6285 metabolites were detected in the three tissues. The differential metabolites were screened and the metabolic pathways of these metabolites in each myopic tissue were labeled, including tryptophan and its metabolites, pyruvate, taurine, caffeine metabolites, as well as neurotransmitters like glutamate and dopamine. Our study suggests that multiple metabolic pathways or different metabolites under the same pathway, might act on different parts of the eyeball and contribute to the occurrence and development of myopia by affecting the energy supply to the ocular tissues, preventing antioxidant stress, affecting scleral collagen synthesis, and regulating various neurotransmitters mutually.

ASSOCIATION OF TESSELLATION DENSITY WITH PROGRESSION OF AXIAL LENGTH AND REFRACTION IN CHILDREN: An Artificial Intelligence-Assisted 4-Year Study

PURPOSE

To investigate fundus tessellation density (TD) and its association with axial length (AL) elongation and spherical equivalent (SE) progression in children.

METHODS

The school-based prospective cohort study enrolled 1,997 individuals aged 7 to 9 years in 11 elementary schools in Mojiang, China. Cycloplegic refraction and biometry were performed at baseline and 4-year visits. The baseline fundus photographs were taken, and TD, defined as the percentage of exposed choroidal vessel area in the photographs, was quantified using an artificial intelligence-assisted semiautomatic labeling approach. After the exclusion of 330 ineligible participants because of loss to follow-up or ineligible fundus photographs, logistic models were used to assess the association of TD with rapid AL elongation (>0.36 mm/year) and SE progression (>1.00 D/year).

RESULTS

The prevalence of tessellation was 477 of 1,667 (28.6%) and mean TD was 0.008 ± 0.019. The mean AL elongation and SE progression in 4 years were 0.90 ± 0.58 mm and -1.09 ± 1.25 D. Higher TD was associated with longer baseline AL (β, 0.030; 95% confidence interval: 0.015-0.046; P < 0.001) and more myopic baseline SE (β, -0.017; 95% confidence interval: -0.032 to -0.002; P = 0.029). Higher TD was associated with rapid AL elongation (odds ratio, 1.128; 95% confidence interval: 1.055-1.207; P < 0.001) and SE progression (odds ratio, 1.123; 95% confidence interval: 1.020-1.237; P = 0.018).

CONCLUSION

Tessellation density is a potential indicator of rapid AL elongation and refractive progression in children. TD measurement could be a routine to monitor AL elongation.

Sympathetic nervous system activity is associated with choroidal thickness and axial length in school-aged children

BACKGROUND/AIMS

We aim to explore the effect of sympathetic nervous system (SNS) on choroid thickness (ChT) and axial length (AL).

METHODS

Students of grade 2 and 3 from a primary school were included and followed for 1 year. Visual acuity, refraction, AL and ChT were measured. Morning urine samples were collected for determining SNS activity by analysing concentrations of epinephrine, norepinephrine and dopamine using the liquid chromatography-tandem mass spectrometry. The most important factor (factor 1) was calculated using factor analysis to comprehensively indicate the SNS activity.

RESULTS

A total of 273 students were included, with an average age of 7.77±0.69 years, and 150 (54.95%) were boys. Every 1 µg/L increase in epinephrine is associated with 1.60 µm (95% CI 0.30 to 2.90, p=0.02) decrease in average ChT. Every 1 µg/L increase in norepinephrine is associated with 0.53 µm (95% CI 0.08 to 0.98, p=0.02) decrease in the ChT in inner-superior region. The factor 1 was negatively correlated with the ChT in the superior regions. Every 1 µg/L increase in norepinephrine was associated with 0.002 mm (95% CI 0.0004 to 0.004, p=0.016) quicker AL elongation. The factor 1 was positively correlated with AL elongation (coefficient=0.037, 95% CI 0.005 to 0.070, p=0.023).

CONCLUSIONS

We hypothesised that chronic stress characterised by elevated level of the SNS, was associated with significant increase in AL elongation, probably through thinning of the choroid.

Macular and peripapillary Choroidal Vascularity Index in children with different refractive status

OBJECTIVES

To characterize choroidal vascular changes in children with different refractive status.

METHODS

A study including 5864 children aged 6-9 years was performed to investigate the choroidal vascular index (CVI) in myopic, emmetropic and hyperopic eyes. Each participant had a comprehensive ocular examination with cycloplegic autorefraction performed, axial length (AL) measured and Swept Source-Optical Coherence Tomography (SS-OCT) scans acquired. Choroidal thickness (ChT) was measured by built-in software, and CVI was calculated using a previously validated self-developed algorithm.

RESULTS

The mean ChT and CVI were 275.88 ± 53.34 μm and 34.91 ± 3.83 in the macula region, and 191.96 ± 46.28 μm and 32.35 ± 4.21 in the peripapillary region. CVI was significantly lowest for myopes, followed by emmetropes and hyperopes (P < 0.001). CVI varied between different sectors separated by the Early Treatment of Diabetic Retinopathy Study (ETDRS) grid (P < 0.001). Macular CVI decreased horizontally from nasal to temporal quadrant with lowest in center fovea, and vertically from superior to inferior quadrants. Peripapillary CVI was highest in the nasal and lowest in the inferior sector. Multiple regression showed that spherical equivalent (SE), AL, intraocular pressure (IOP), ChT, age, and gender were significantly related to CVI (P < 0.05).

CONCLUSIONS

In children, the distribution of CVI in the posterior pole is not uniform. A decreased CVI was observed from hyperopia to myopia and was associated with decreased SE, elongated AL, and choroidal thinning. Further study of changes in CVI during myopia onset and progression is required to better understand the role of the choroidal vasculature in myopia development.

Influence of high altitude on choroid thickness, retinal thickness, and myopia: A cross-sectional study comparing adolescents in Shanghai and Tibet

PURPOSE

This study aimed to explore the influence of high altitude on myopia, macular choroidal thickness (mCT), and macular retinal thickness (mRT) in adolescents.

METHODS

Two schools, one in Shanghai (at sea level) and one in Shigatse, Tibet (more than 4000 m above sea level), were selected. Refractive error was measured by an autorefractor instrument and subjective refraction, and mCT and mRT were measured at three concentric circles by optical coherence tomography. Student's t -test, Chi-square test, and multiple linear regression analyses were used to analyze the data.

RESULTS

A total of 1114 participants (657 and 457 in Shanghai and Tibet, respectively) were enrolled in this cross-sectional study. The average age of the participants was 18.81 ± 1.10 years, and 44.34% were males. The spherical equivalent (SE) of adolescents in Shanghai was significantly lower than that of adolescents in Tibet (-4.14 ± 2.37 D and -2.12 ± 1.87 D, P < 0.01). The prevalence of myopia and high myopia among adolescents in Shanghai (94.52%, 19.48%) was significantly higher than those among adolescents in Tibet (44.74%, 2.41%) ( P < 0.01). The mCT of Tibetan adolescents was significantly thicker than that of Shanghai adolescents (295.80 ± 62.46 μm and 218.71 ± 61.42 μm, P < 0.01), especially the central mCT. The mRT of Tibetan adolescents was also thicker than that of Shanghai adolescents (301.42 ± 23.26 μm and 281.04 ± 12.24 μm, P < 0.01).

CONCLUSIONS

Compared with Shanghai adolescents, the choroid of Tibet adolescents is thicker, and the myopia prevalence is lower. It is speculated that increased altitude is associated with the thickening of mCT and a low myopia prevalence.

Assessment of macular choroidal and retinal thickness: a cohort study in Tibetan healthy children

This research investigates the distribution, progressive changes, and contributing factors of macular choroidal and retinal thickness in Tibetan children utilizing swept-source optical coherence tomography (SS-OCT). The Lhasa childhood study recruited 1632 students from seven primary schools in Lhasa. These participants underwent OCT and ophthalmological evaluations, encompassing retinal and choroidal thickness measurements, refractive error, axial length (AL), and systemic examinations. The median age of the scholars was 8.57 ± 0.50 years with a median spherical equivalent (SE) of 0.19 ± 1.28D. Multivariate regression analysis revealed that thinner macular choroid thickness was correlated with lower value of SE, worse best-corrected visual acuity, higher mean arterial blood pressure (MABP) and boys, while retinal thickness was associated with better image quality and lower value of SE. The choroid and retina were significantly thinner in myopic children. SE was positively related to the thickness of all choroidal and full retinal subregions. In comparison to baseline data from 20 months prior, most regions of the full retina had significantly thinned. Choroidal thickness of Tibetan children is thinner than that of same-age children from other regions. Thinning of retina, the outer-sector GCC and GCIPL may be specified as a follow-up and prognostic indicator for myopia.

Diurnal retinal and choroidal gene expression patterns support a role for circadian biology in myopia pathogenesis

The prevalence of myopia (nearsightedness) is increasing to alarming levels, but its etiology remains poorly understood. Because both laboratory and clinical findings suggest an etiologic role for circadian rhythms in myopia development, we assayed gene expression by RNA-Seq in retina and choroid at the onset of unilateral experimental myopia in chick, isolating tissues every 4 h during a single 24-h period from myopic and contralateral control eyes. Occluded versus open eye gene expression differences varied considerably over the 24-h sampling period, with some occurring at multiple times of day but with others showing differences at only a single investigated timepoint. Some of the genes identified in retina or choroid of chick myopia were previously identified as candidate genes for common human myopia. Like differentially expressed genes, pathways identified by Gene Set Enrichment Analysis also varied dramatically by sampling time. Considered with other laboratory data, human genetic and epidemiology data, these findings further implicate circadian events in myopia pathogenesis. The present results emphasize a need to include time of day in mechanistic studies of myopia and to assess circadian biology directly in trying to understand better the origin of myopia and to develop more effective therapies.

Understanding Posterior Staphyloma in Pathologic Myopia: Current Overview, New Input, and Perspectives

Posterior staphyloma (PS) is considered the hallmark of pathologic myopia and is defined as an outpouching of a circumscribed portion of the eyeball with a radius of curvature smaller than that of the adjacent zone. Although more common in eyes with high myopia, it can affect those without it. The presence of PS is associated with a structurally and functionally worse course of high myopia that can lead to visual disability. Unfortunately, the pathogenesis of PS is unclear so far. Thus, due to the increasing prevalence of myopia which has been further exacerbated by the advent of COVID-19 lockdown, researchers are eager to elucidate the pathogenesis of pathologic myopia and that of its complications, especially PS, which will allow the development of preventive strategies. The aim of this work was to review the morphological characteristics of PS with emphasis on similarities with peripapillary staphyloma and to discuss the pathogenesis of PS considering recent suggestions about that of peripapillary staphyloma.

Axial Length Control Is Associated With a Choroidal Thickness Increase in Myopic Adolescents After Orthokeratology

OBJECTIVE

To investigate the changes in choroidal thickness and axial length after orthokeratology in adolescents with low-to-moderate myopia and to explore the relationship between choroidal thickness and axial length variation.

METHODS

Thirty eyes with low-to-moderate myopia were retrospectively studied, and optometric data were collected before and after 6 months of continuous orthokeratology. Axial length and choroidal and foveal thicknesses were measured using optical biometry and enhanced depth imaging-spectral domain optical coherence tomography, respectively.

RESULTS

Axial length in the low myopia group increased ( P <0.001) after 6 months of orthokeratology, and the variation was greater than that in the moderate myopia group ( P <0.05). The subfoveal choroidal thickness in low and moderate myopia groups increased ( P <0.01), and the variation was greater in the moderate myopia group ( P <0.05). Choroidal thickness in all seven measured spots increased, with the variation of subfovea, nasal 1 mm to fovea, and temporal 1 mm to fovea being statistically significant ( P <0.001, P <0.05, and P <0.05). The change in axial length was negatively associated with subfoveal and average choroidal thicknesses ( P <0.01).

CONCLUSION

Adolescents with moderate myopia presented better axial length control after 6 months of orthokeratology. The choroidal thickness of low and moderate myopic eyes increased, and the variation was more significant in moderate myopic eyes. The axial length control effects can be associated with an increase in the subfoveal and average choroidal thickness.

Efficiency and Related Factors of Multifocal Soft Contact Lenses in Controlling Myopia

OBJECTIVE

To evaluate ocular changes in Chinese myopic children wearing multifocal soft contact lenses and explore their efficiency and related factors.

METHOD

This was a prospective, double-blind, randomized controlled study. A total of 36 myopic children aged 7 to 12 years were randomly divided into groups wearing multifocal soft contact lenses (MFCLs) or single-vision soft contact lenses (SVCLs) and followed up for 12 months. The spherical equivalent (SE), axial length (AL), choroidal thickness, and vascularity were measured before commencement and after 6 and 12 months of lens wear. Correlation between ocular changes and myopia progression was determined.

RESULTS

A total of 32 subjects (6 males and 26 females) completed the study and were included in the analysis. After 12 months of lens wear, both the AL elongation (0.25±0.22 vs. 0.43±0.16 mm, P=0.011) and the SE progression (-0.69±0.69 D vs. -1.45±0.56 D, P=0.002) of the MFCL group were significantly lower than those of the SVCL group. After 12 months, the progression of myopia was significantly correlated with changes of the choroid in the MFCL wearers, whereas no such correlation was observed in the SVCL group.

CONCLUSION

Multifocal soft contact lens can slow myopia progression, and this effect may be related to the changes of the choroid.

Correlation between refractive errors and ocular biometric parameters in children and adolescents: a systematic review and meta-analysis

BACKGROUND

Refractive errors are one of the most common ocular conditions among children and adolescents, with myopia showing an increasing prevalence and early onset in this population. Recent studies have identified a correlation between refractive errors and ocular biometric parameters.

METHODS

A systematic search was conducted in electronic databases including PubMed, EMBASE, Cochrane Library, Web of Science, and Medline from January 1, 2012, to May 1, 2023. Various ocular biometric parameters were summarized under different refractive states, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), corneal curvature (CC), Corneal curvature radius (CR),axial length-to-corneal radius ratio (AL/CR ratio), choroidal thickness (ChT), retinal thickness (RT), retinal nerve fiber layer thickness (RNFL), and retinal blood density (VD). The differences in these parameters among different refractive states were analyzed using Stata software with fixed or random-effects models, taking into account the assessed heterogeneity level.

RESULTS

This meta-analysis included a total of 69 studies involving 128,178 eyes, including 48,795 emmetropic eyes, 60,691 myopic eyes, 13,983 hyperopic eyes, 2,040 low myopic eyes, 1,201 moderate myopic eyes, and 1,468 high myopic eyes. The results of our study demonstrated that, compared to the control group (emmetropic group), the myopic group and low, moderate, and high myopic groups showed significant increases in AL, AL/CR ratio, and ACD, while the hyperopic group exhibited significant decreases. Compared to the control group, the myopic group had a significantly increase for CC, while CR, CCT, perifoveal RT, subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal (except nasal) ChT, and pRNFL (except temporal) significantly decreased. Compared to the control group, the hyperopic group had a significantly increase for subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal ChT, and nasal pRNFL. Compared to the control group, the low and moderate myopic groups had a significantly decreases for the CCT, parafoveal RT (except nasal), perifoveal RT (except nasal), and pRNFL (except superior and temporal). Compared to the control group, the high myopic group had a significantly increase for CR, while LT, perifoveal ChT (except nasal), parafoveal RT, perifoveal RT, and pRNFL (except temporal) had significant decreased.

CONCLUSION

The changes of ocular biometric parameters in children and adolescents are closely related to refractive errors. Ocular biometric parameters devices, as effective non-invasive techniques, provide objective biological markers for monitoring refractive errors such as myopia.

Study on the relationship between scoliosis and vision problems: A narrative review

Adolescent scoliosis is one of the most common surgical disorders of the pediatric spine. With timely detection and early treatment, most scoliotic children can avoid major and expensive surgery. Vision problems are also frequently found at an early age and can take a toll on individuals quality of life. However, scoliosis, a severe health hazard to adolescents, is often accompanied by vision problems clinically, including myopia, astigmatism, strabismus, amblyopia, horizontal paralysis, and blindness. And people with genetic defects have a higher probability of suffering both spinal problems and vision problems than those with nongenetic defects. However, many individuals viewed scoliosis and vision problems as 2 irrelevant diseases. This review searched PubMed, China National Knowledge Infrastructure, and Web of Science for studies on adolescent, scoliosis, eye diseases, myopia, strabismus, spinal disorders, and vision problems for almost 3 decades, and thus confirmed the potential relationship between adolescent scoliosis and vision problems.

Choroidal thickness in relation to diopter and axial length among myopic children

Purpose

The aim of this study was to analyze the relationship between diopter (D) and choroidal thickness in myopic children by describing the values of choroidal thickness, and explore choroidal thickness as an important indicator for evaluating the progression of myopia.

Methods

The study included myopic and emmetropic children aged 6-14 years (156 eyes) from the Second Hospital of Dalian Medical University. The participants were divided into four groups according to the spherical equivalent refraction (SER): low myopes, moderate myopes, high myopes, and emmetropes. Choroidal thickness was measured in nine areas using the Early Treatment Diabetic Retinopathy Study (ETDRS) grid layout, which divided the areas into concentric circles of 0 × 0 mm, 3 × 3 mm, and 5 × 5 mm from the Sub Fovea. The images were obtained manually with spectral-domain optical coherence tomography scanner.

Results

There were significant differences of choroidal thickness in the nine areas of the ETDRS grid for all myopes. The distribution of choroidal thickness in low and moderate myopes were different from that in high myopes. In the horizontal direction, choroidal thickness decreased from the temporal to nasal areas for all myopes. In the vertical direction, the choroidal thickness in the perifovea was smaller than that in the parafovea (SER ≥ -2.75D), and the choroidal thickness in the perifovea was greater than that in the parafovea (SER < -2.75D). When comparing emmetropes with myopes, the closer the choroidal thickness was to the central fovea, the more significant the differences were, while the differences were smaller to the perifovea. Among all children, choroidal thickness was positive to SER and negative to axial length (AL) in all areas. For every 1D increase in myopia, the subfoveal choroidal thickness decreased by 13 μm, and for every 1 mm increase in AL, the subfoveal choroidal thickness decreased by 23 μm. Furthermore, SER and AL showed the strongest correlation with choroidal thickness in the inferior area.

Conclusion

Optical coherence tomography results revealed choroidal thickness was thinner in myopic children. Choroidal thickness was positive to SER and negative to AL. Therefore, we consider choroidal thickness to be an important indicator for evaluating the myopia progress.

Effects of posterior staphyloma on choroidal structure in myopic adults: a retrospective study

BACKGROUND

Studies on the choroid of myopic eyes with posterior staphyloma have shown that choroidal thickness decreased. This retrospective study further analysed the effects of posterior scleral staphyloma on choroidal blood vessels and matrix components compared to non-pathological myopia.

METHODS

In this cross-sectional study, ninety-one eyes were divided into pathological (posterior staphyloma) and non-pathological myopia. The latter was further divided into three groups (Group 1: 26 mm ≤ axial length; Group 2: 24 mm ≤ axial length < 26 mm; Group 3: 22 mm ≤ axial length < 24 mm). Choroidal thickness, total choroidal area, luminal area, stromal area, and choroidal vascularity index were calculated.

RESULTS

The CVI in N1, N2, I1, S2 of the posterior staphyloma group were lower than those of group 1 (both P < 0.05). The mean height of posterior staphyloma was associated with mean CT (Pearson correlation: r = -0.578, P = 0.039) but not with the mean CVI in posterior staphyloma group. In all groups, the mean choroidal thickness, total choroidal area, luminal area, and stromal area were significantly associated with axial length (P < 0.001), and the mean choroidal vascularity index was significantly associated with the mean choroidal thickness (P < 0.001).

CONCLUSION

The choroidal structure of pathological myopia with posterior staphyloma and non-pathological myopia with longer axial length demonstrates alterations in which choroidal vessels are more impaired than the stroma. A lower choroidal vascularity index should be alert to pathological changes for myopia with axial length > 26 mm.

Six-month repeated irradiation of 650 nm low-level red light reduces the risk of myopia in children: a randomized controlled trial

PURPOSE

To evaluate whether the six-month repeated irradiation of 650 nm low-level red light (LLRL) decreases the risk of myopia onset in children.

METHODS

This was a single-masked, randomized controlled trial. A total of 112 children (aged 6-12 years) were enrolled and randomized to the treatment group or control group in a 1:1 ratio. The cycloplegic spherical equivalent error (SER) of children at baseline was -0.5 diopter (D) to 3D. Children in the treatment group were irradiated with the 650 nm LLRL for 6 min daily. No intervention was given to the control. The primary outcomes are myopia incidence, change in cycloplegic SER, and change in axial length (AL).

RESULTS

For the treatment group and control group, the six-month myopia incidence rates were 1.8% (95% confidence interval, CI: 0.2-4.9%) and 12.5% (95% CI: 5.5-21.9%), respectively. The difference was significant (p = 0.028). The median changes in AL for the treatment group and control group were -0.02 (interquartile range, IQR: -0.12 to 0.06) mm, and 0.09 (IQR: 0-0.18) mm, respectively. The difference was significant (p < 0.001). The median changes in cycloplegic SER for the treatment group and control group were 0 (IQR: 0-0.25) D, and -0.125 (IQR: -0.375 to 0) D, respectively. The difference was significant (p < 0.001). There was no adverse event.

CONCLUSION

The repeated irradiation of 650 nm LLRL may have a strong effect for myopia prevention in children, without risk of adverse events.

TRIAL REGISTRATION

this trial is retrospectively registered in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ), the registration number is ChiCTR2200058963.

Myopic Vascular Changes Revealed by Optical Tomography Angiography and Their Association with Myopic Fundus Manifestations

INTRODUCTION

We aimed to quantify and evaluate fundal vascular changes at different severities of myopia using optical tomography angiography (OCTA) and explore their association with fundus changes captured by ultra-widefield (UWF) fundus cameras.

METHODS

Seventy-four participants with myopia were enrolled in the study and underwent basic ophthalmic examination, OCTA, and UWF fundus photography. Multiple parameters were obtained using OCTA (flow area, structure thickness, and vessel density) and UWF fundus cameras (tessellation and parapapillary atrophy [PPA]).

RESULTS

The right eye of 30 participants with low and moderate myopia and 44 participants with high myopia (HM) were included. Patients with HM had a larger flow area of the outer retina (FA-OR) and a smaller thickness of choroid (TC). Axial length was significantly correlated with retinal and choroidal flow area and thickness in the different zones. The PPA area was positively correlated with FA-OR and negatively correlated with TC. Tessellation exhibited different levels of correlation with OCTA parameters regarding the flow area, thickness, and vessel density of the fundal layers, mainly in the inner retina.

CONCLUSION

FA-OR and TC exhibited sensitive changes in patients with HM and axial elongation; therefore, they could serve as predictive OCTA biomarkers. The PPA and tessellation were connected to the vascular and structural changes revealed by OCTA.

Defocus incorporated multiple segments (DIMS) spectacle lenses increase the choroidal thickness: a two-year randomized clinical trial

BACKGROUND

Myopia control interventions, such as defocus incorporated multiple segments (DIMS) spectacle lenses, have been adopted in school-aged children to reduce the prevalence of myopia and its complications. This study aimed to investigate the effect of DIMS spectacle lenses on subfoveal choroidal thickness (SfChT) over a period of two years, as the choroidal response to myopic control is a crucial factor in exploring its potential effect on predicting myopia progression.

METHODS

This study involved a secondary analysis of our previous randomized clinical trial. Myopic school-aged children aged 8-13 years were recruited in a two-year study investigating the effect of DIMS spectacle lenses on myopia progression. The treated group received DIMS spectacle lenses (n = 78), while the control group was treated with a pair of single vision (SV) spectacle lenses (n = 80). SfChT was monitored at 1 week, 1, 3, 6, 12, 18 and 24 months post lens wear using spectral-domain optical coherence tomography and a custom made auto-segmentation algorithm utilizing convolutional neural networks.

RESULTS

SfChT increased significantly after one week of DIMS spectacle lens wear compared to those wearing SV spectacle lenses (adjusted mean change relative to baseline ± SEM at one week; DIMS vs. SV, 6.75 ± 1.52 µm vs. - 3.17 ± 1.48 µm; P < 0.0001, general linear model). The thickness of choroid increased to 13.64 ± 2.62 µm after 12 months of DIMS lens wear while the choroid thinned in SV group (- 9.46 ± 2.55 µm). Choroidal changes demonstrated a significant negative association with axial elongation over two years in both the DIMS and SV groups. Choroidal change at three months significantly predicted the changes in AL at 12 months after controlling the effect of age and gender.

CONCLUSIONS

Our study demonstrated a significant choroidal thickening in response to myopic defocus incorporated in a spectacle lens after one week of lens wear, sustained over the two-year study period. The results suggested that choroidal changes at three months may help predict changes in axial length after one year. Trial registration ClinicalTrials.gov. Myopia control with the multi-segment lens. NCT02206217. Registered 29 July 2014, https://clinicaltrials.gov/ct2/show/study/NCT02206217.

Effects of dopamine D2 receptor antagonists on retinal pigment epithelial/choroid complex metabolism in form-deprived myopic guinea pigs

The retinal pigment epithelial (RPE)/choroid complex regulates myopia development, but the precise pathogenesis of myopia remains unclear. We aimed to investigate the changes in RPE/choroid complex metabolism in a form deprivation myopia model after dopamine D2 receptor (D2R) modulation. Guinea pigs were randomly divided into normal (NC), form deprivation myopia (FDM), and FDM treated with dopamine D2R antagonist groups. Differential metabolites were screened using SIMCA-P software and MetaboAnalyst metabolomics analysis tool. Functions of differential metabolites were analyzed using KEGG enrichment pathways. Relative to the NC group, 38 differential metabolites were identified, comprising 29 increased metabolites (including nicotinic acid, cytosine, and glutamate) and 9 decreased metabolites, of which proline exhibited the largest decrease. Pathway analysis revealed regulation of arginine/proline and aspartate/glutamate metabolism. Intravitreal D2R antagonist injection increased proline concentrations and activated arginine/proline and purine metabolism pathways. In sum, D2R antagonists alleviated the myopia trend of refractive biological parameters in form deprivation myopic guinea pigs, suggesting the involvement of dopamine D2R signaling in myopia pathogenesis. The RPE/choroid may provide glutamate to the retina by activating proline metabolism via metabolic coupling with the retina. Dopamine D2R antagonism may modulate proline/arginine metabolic pathways in the RPE/choroid and regulate metabolism, information presentation, and myopia.

Correlation analysis of aqueous humor metabolomics with myopic axial length and choroidal parameters

BACKGROUND

To explore differential metabolites in the aqueous humor of patients with different axial lengths and their correlations with axial length and choroidal parameters.

METHODS

In this study, we included 12 patients with axial lengths less than 24 mm, 11 patients with axial lengths between 24 and 26 mm, and 11 patients with axial lengths greater than 26 mm. We collected their aqueous humor samples during cataract surgery for liquid chromatography-mass spectrometry metabolomic analysis. Simultaneously, we collected relevant clinical parameters such as axial length, subfoveal choroidal thickness, and choroidal vascular index. Correlations between clinical data, differential metabolites, and clinical indicators were analyzed. In addition, we plotted receiver operating characteristic curves.

RESULTS

The results showed that axial length was significantly negatively correlated with choroidal thickness (r=-0.7446, P < 0.0001), and that several differential metabolites were significantly correlated with certain clinical parameters. After analyzing receiver operating characteristic curves, 5-methoxytryptophol and cerulenin were found to have excellent discriminative power, demonstrating their potential as biomarkers. In the enrichment analysis, we found that the differential metabolites among each group were involved in several special pathways (Taurine and Hypotaurine Metabolism, Vitamin B6 Metabolism, Pantothenate, and coenzyme A Biosynthesis), suggesting that abnormalities in these metabolic pathways may play a role in the process of axial myopia.

CONCLUSIONS

Our study identified alterations in certain metabolic pathways in different axial lengths. At the same time, we found several metabolites with significant correlation with clinical indicators, among which 5-methoxytryptophol and cerulenin were associated with axial myopia.

CLINICAL TRIAL REGISTRATION

Registration date:11/04/2022.

TRIAL REGISTRATION NUMBER

ChiCTR2200058575.

TRIAL REGISTRY

The First Affiliated Hospital of the Zhejiang University School of Medicine.

Defocus-induced spatial changes in choroidal thickness of chicks observed by wide-field swept-source OCT

Choroid has been claimed to be of importance during ocular development. However, how the choroid responds spatially to different visual cues has not been fully understood. The aim of this study was to investigate defocus-induced spatial changes in choroidal thickness (ChT) in chicks. Eight 10-day-old chicks were fitted monocularly with -10 D or +10 D lenses (day 0), which were removed seven days later (day 7). The ChT was measured on days 0, 7, 14, and 21 using wide-field swept-source optical coherence tomography (SS-OCT) and analyzed with custom-made software. Comparisons of the ChT in the central (1 mm), paracentral (1-3 mm), and peripheral (3-6 mm) ring areas and the ChT in the superior, inferior, nasal, and temporal regions were conducted. Axial lengths and refractions were also evaluated. In the negative lens group, the global ChT of the treated eyes was significantly less than that of the fellow eyes on day 7 (interocular difference: 179.28 ± 25.94 μm, P = 0.001), but thicker on day 21 (interocular difference: 241.80 ± 57.13 μm, P = 0.024). These changes were more pronounced in the central choroid. The superior-temporal choroid changed more during induction but less during recovery. In the positive lens group, the ChT of both eyes increased on day 7 and decreased on day 21, with most changes occurring in the central region, too. The inferior-nasal choroid of the treated eyes changed more during induction but less during recovery. These results provide evidence for regionally asymmetric characteristics of the choroidal response to visual cues and insights into the underlying mechanisms of emmetropization.

Targeting choroidal vasculopathy via up-regulation of tRNA-derived fragment tRF-22 expression for controlling progression of myopia

BACKGROUND

Myopia has emerged as a major public health concern globally, which is tightly associated with scleral extracellular matrix (ECM) remodeling and choroidal vasculopathy. Choroidal vasculopathy has gradually been recognized as a critical trigger of myopic pathology. However, the precise mechanism controlling choroidal vasculopathy remains unclear. Transfer RNA-derived fragments (tRFs) are known as a novel class of small non-coding RNAs that plays important roles in several biological and pathological processes. In this study, we investigated the role of tRF-22-8BWS72092 (tRF-22) in choroidal vasculopathy and myopia progression.

METHODS

The tRF-22 expression pattern under myopia-related stresses was detected by qRT-PCR. MTT assays, EdU incorporation assays, Transwell migration assays, and Matrigel assays were conducted to detect the role of tRF-22 in choroidal endothelial cell function in vitro. Isolectin B4 staining and choroidal sprouting assay ex vivo were conducted to detect the role of tRF-22 in choroidal vascular dysfunction in vivo. Immunofluorescent staining, western blot assays and ocular biometric parameters measurement were performed to examine whether altering tRF-22 expression in choroid affects scleral hypoxia and ECM remodeling and myopia progression in vivo. Bioinformatics analysis and luciferase activity assays were conducted to identify the downstream targets of tRF-22. RNA-sequencing combined with m6A-qPCR assays were used to identify the m6A modified targets of METTL3. Gain-of-function and Loss-of-function analysis were performed to reveal the mechanism of tRF-22/METTL3-mediated choroidal vascular dysfunction.

RESULTS

The results revealed that tRF-22 expression was significantly down-regulated in myopic choroid. tRF-22 overexpression alleviated choroidal vasculopathy and retarded the progression of myopia in vivo. tRF-22 regulated choroidal endothelial cell viability, proliferation, migration, and tube formation ability in vitro. Mechanistically, tRF-22 interacted with METTL3 and blocked m6A methylation of Axin1 and Arid1b mRNA transcripts, which led to increased expression of Axin1 and Arid1b.

CONCLUSIONS

Our study reveals that the intervention of choroidal vasculopathy via tRF-22-METTL3- Axin1/Arid1b axis is a promising strategy for the treatment of patients with myopic pathology.

Changes in Choroidal Thickness and Retinal Activity with a Myopia Control Contact Lens

PURPOSE

The axial elongation in myopia is associated with some structural and functional retinal changes. The purpose of this study was to investigate the effect of a contact lens (CL) intended for myopia control on the choroidal thickness (ChT) and the retinal electrical response.

METHODS

Ten myopic eyes (10 subjects, 18-35 years of age) with spherical equivalents from -0.75 to -6.00 diopters (D) were enrolled. The ChT at different eccentricities (3 mm temporal, 1.5 mm temporal, sub-foveal ChT, 1.5 mm nasal, and 3 mm nasal), the photopic 3.0 b-wave of ffERG and the PERG were recorded and compared with two material-matched contact lenses following 30 min of wear: a single-vision CL (SV) and a radial power gradient CL with +1.50 D addition (PG).

RESULTS

Compared with the SV, the PG increased the ChT at all eccentricities, with statistically significant differences at 3.0 mm temporal (10.30 ± 11.51 µm, p = 0.020), in sub-foveal ChT (17.00 ± 20.01 µm, p = 0.025), and at 1.5 mm nasal (10.70 ± 14.50 µm, p = 0.044). The PG decreased significantly the SV amplitude of the ffERG photopic b-wave (11.80 (30.55) µV, p = 0.047), N35-P50 (0.90 (0.96) µV, p = 0.017), and P50-N95 (0.46 (2.50) µV, p = 0.047). The amplitude of the a-wave was negatively correlated with the ChT at 3.0T (r = -0.606, p = 0.038) and 1.5T (r = -0.748, p = 0.013), and the amplitude of the b-wave showed a negative correlation with the ChT at 1.5T (r = -0.693, p = 0.026).

CONCLUSIONS

The PG increased the ChT in a similar magnitude observed in previous studies. These CLs attenuated the amplitude of the retinal response, possibly due to the combined effect of the induced peripheral defocus high-order aberrations impacting the central retinal image. The decrease in the response of bipolar and ganglion cells suggests a potential retrograde feedback signaling effect from the inner to outer retinal layers observed in previous studies.

Evidence of vascular involvement in myopia: a review

The benign public perception of myopia (nearsightedness) as a visual inconvenience masks the severity of its sight-threatening consequences. Myopia is a significant risk factor for posterior pole conditions such as maculopathy, choroidal neovascularization and glaucoma, all of which have a vascular component. These associations strongly suggest that myopic eyes might experience vascular alterations prior to the development of complications. Myopic eyes are out of focus because they are larger in size, which in turn affects their overall structure and function, including those of the vascular beds. By reviewing the vascular changes that characterize myopia, this review aims to provide an understanding of the gross, cellular and molecular alterations identified at the structural and functional levels with the goal to provide an understanding of the latest evidence in the field of experimental and clinical myopia vascular research. From the evidence presented, we hypothesize that the interaction between excessive myopic eye growth and vascular alterations are tipping-points for the development of sight-threatening changes.

Contralateral effect in progression and recovery of lens-induced myopia in mice

PURPOSE

Apart from genetic factors, recent animal studies on myopia have focused on localised mechanisms. In this study, we aimed to examine the contralateral effects of monocular experimental myopia and recovery, which cannot be explained by a mere local mechanism.

METHODS

One eye of 3-week-old C57BL/6 male mice was fitted with a -30 dioptre (D) lens. The mice were distributed into two groups based on different conditions in the contralateral eye: either no lens (NLC) (n = 10) or a Plano lens on the contralateral eye (PLC) group (n = 6). Mice receiving no treatment on either eye were set as a control group (n = 6). Lenses were removed after 3 weeks of myopia induction. All mice were allowed to recover for 1 week in the same environment. Refractive status, axial length (AL) and choroidal thickness were measured before myopia induction, after 1 and 3 weeks of lens wear and after 1 week of recovery.

RESULTS

One week after removing the lenses, complete recovery was observed in the eyes that wore the -30 D lenses. In both the PLC and NLC groups, the refractive status showed a myopic shift after lens removal. Additionally, the choroid was significantly thinned in these eyes. The -30 D wearing eye showed a significant increase in AL after 3 weeks of lens wear. While the AL of the -30 D wearing eye ceased to grow after the lens was removed, the AL in the PLC and NLC contralateral eyes increased, and the binocular ALs gradually converged.

CONCLUSIONS

Recovery of lens-induced myopia was observed in mouse models. In the fellow eyes, the effects, including thinning of the choroid and changes in refractive status, were triggered by contralateral visual cues.

Diurnal changes in choroidal optical coherence tomography angiography indices over 24 hours in healthy young adults

This prospective study investigated the magnitude and pattern of variation in choroidal optical coherence tomography angiography (OCT-A) indices every 4 h over 24 h in healthy young myopic (n = 24) and non-myopic (n = 20) adults. Choriocapillaris and deep choroid en-face images from macular OCT-A scans were analysed from each session to extract magnification-corrected vascular indices including choriocapillaris flow deficit number, size and density and deep choroid perfusion density in the sub-foveal, sub-parafoveal, and sub-perifoveal regions. Choroidal thickness was also obtained from structural OCT scans. Significant variations over 24 h (P < 0.05) were observed in most of the choroidal OCT-A indices excluding sub-perifoveal flow deficit number, with peaks observed between 2 to 6 AM. For myopes, peaks occurred significantly earlier (3-5 h), and the diurnal amplitude was significantly greater for sub-foveal flow deficit density (P = 0.02) and deep choroidal perfusion density (P = 0.03) compared with non-myopes. Choroidal thickness also showed significant diurnal changes (P < 0.05) with peaks between 2 to 4 AM. Significant correlations were found between diurnal amplitudes or acrophases of choroidal OCT-A indices and choroidal thickness, intraocular pressure, and systemic blood pressure. This provides the first comprehensive diurnal assessment of choroidal OCT-A indices over 24 h.

Longitudinal Changes and Predictive Value of Choroidal Thickness for Myopia Control after Repeated Low-Level Red-Light Therapy

PURPOSE

To evaluate longitudinal changes in macular choroidal thickness (mCT) in myopic children treated for 1 year with repeated low-level red-light (RLRL) therapy and their predictive value for treatment efficacy on myopia control.

DESIGN

A secondary analysis of data from a multicenter, randomized controlled trial (RCT; NCT04073238).

PARTICIPANTS

Myopic children aged 8-13 years who participated in the RCT at 2 of 5 sites where mCT measurements were available.

METHODS

Repeated low-level red-light therapy was delivered using a home-use desktop light device that emitted red-light at 650 nm. Choroidal thickness was measured by SS-OCT at baseline and 1-, 3-, 6-, and 12-month follow-ups. Visual acuity, axial length (AL), cycloplegic spherical equivalent refraction (SER), and treatment compliance were measured.

MAIN OUTCOME MEASURES

Changes in mCT at 1, 3, 6, and 12 months relative to baseline, and their associations with myopia control.

RESULTS

A total of 120 children were included in the analysis (RLRL group: n = 60; single-vision spectacle [SVS] group: n = 60). Baseline characteristics were well balanced between the 2 groups. In the RLRL group, changes in mCT from baseline remained positive over 1 year, with a maximal increase of 14.755 μm at 1 month and gradually decreasing from 5.286 μm at 3 months to 1.543 μm at 6 months, finally reaching 9.089 μm at 12 months. In the SVS group, mCT thinning was observed, with changes from baseline of -1.111, -8.212, -10.190, and -10.407 μm at 1, 3, 6, and 12 months, respectively. Satisfactory myopia control was defined as annual progression rates of less than 0, 0.05, or 0.10 mm for AL and less than 0, 0.25, or 0.50 diopters for SER. Models that included mCT changes at 3 months alone had acceptable predictive discrimination of satisfactory myopia control over 12 months, with areas under the curve of 0.710-0.786. The predictive performance of the models did not significantly improve after adding age, gender, and baseline AL or SER.

CONCLUSIONS

This analysis from a multicenter RCT found RLRL induced sustained choroidal thickening over the full course of treatment. Macular choroidal thickness changes at 3 months alone can predict 12-month myopia control efficacy with reasonable accuracy.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Evaluation of retinal vascular density and related factors using OCTA in children and adolescents with myopia without maculopathy

BACKGROUND

Myopia is the most common ophthalmic condition worldwide with a rapidly increasing prevalence. This study aimed to compare the retinal microvasculature in the superficial capillary plexus (SCP) in children and adolescents with mild and moderate/high myopia using optical coherence tomography angiography, determine the relationship between retinal parameters and axial length (AL), and understand the occurrence and progression of myopia in microcirculation.

METHODS

This prospective observational study included 39 participants with mild myopia and 33 participants with moderate/high myopia. Vessel density (VD) and perfusion density (PD) in the SCP, the foveal avascular zone (FAZ), and AL were compared between the groups and the relationship between these retinal parameters and AL was assessed.

RESULTS

No difference in SCP VD or PD was observed between the two groups. The FAZ did not differ significantly between groups whereas significant differences in age, height, refractive status, and AL were observed. Significantly shorter AL was observed in participants with mild myopia compared with the moderate/high myopia group. Age was positively correlated with height (r = 0.852) and refractive status was negatively correlated with AL (r = -0.588). AL was positively correlated with VD (r = 0.317) and PD (r = 0.308) in the SCP and AL was negatively correlated with the FAZ (r = -0.434).

CONCLUSIONS

This study revealed that superficial foveal microvessel density was unaffected in children and adolescents without pathological myopia. However, myopia progression was associated with a change in AL, and an AL increase altered macular blood flow.