Ciliary muscles contraction leads to axial length extension--The possible initiating factor for myopia.

PURPOSE: This study aimed to investigate the underlying factors driving the onset of myopia, specifically the role of the ciliary muscle's contraction in the elongation of the axial length of the eye. METHODS: The retrospective study was conducted utilizing data from three ophthalmic centers in Shanghai and Beijing. Both Chinese and Caucasian children were involved. The axial length of the subjects' eyes was measured in both relaxed and contracted state of the ciliary muscle. A comprehensive mechanical model was also developed to observe the influence of ciliary muscle contraction on the axial length. RESULTS: This study included a sample of 198 right eyes of 198 myopic children. Of these, 97 were male and 101 were female, 126 were of Chinese ethnicity and 72 were Caucasian. The age of onset for myopia ranged from 5.9 to 16.9 years old. The axial length of the eye decreased 0.028 ± 0.007mm following dilation, indicating relaxation of the ciliary muscle (t paired student = 15.16, p = 6.72 x 10-35). In contrast, ciliary muscle contraction resulted in an increase in axial length. Considering proportionality, a significant 90.4% (179 eyes) exhibited a reduced axial length, while a minor 9.6% (19 eyes) demonstrated an increase post-mydriasis. Finite element modeling demonstrated that muscle contraction caused a tension force that transmits towards the posterior pole of the eye, causing it to extend posteriorly. CONCLUSION: The contraction of the ciliary muscle leads to an extension of the axial length. This could potentially be the initiating factor for myopia.

Early Alterations in Inner-Retina Neural and Glial Saturated Responses in Lens-Induced Myopia.

Purpose: Myopic marmosets are known to exhibit significant inner retinal thinning compared to age-matched controls. The purpose of this study was to assess inner retinal activity in marmosets with lens-induced myopia compared to age-matched controls and evaluate its relationship with induced changes in refractive state and eye growth. Methods: Cycloplegic refractive error (Rx), vitreous chamber depth (VCD), and photopic full-field electroretinogram were measured in 14 marmosets treated binocularly with negative contact lenses compared to 9 untreated controls at different stages throughout the experimental period (from 74 to 369 days of age). The implicit times of the a-, b-, d-, and photopic negative response (PhNR) waves, as well as the saturated amplitude (Vmax), semi-saturation constant (K), and slope (n) estimated from intensity-response functions fitted with Naka-Rushton equations were analyzed. Results: Compared to controls, treated marmosets exhibited attenuated b-, d-, and PhNR waves Vmax amplitudes 7 to 14 days into treatment before compensatory changes in refraction and eye growth occurred. At later time points, when treated marmosets had developed axial myopia, the amplitudes and implicit times of the b-, d-, and PhNR waves were similar between groups. In controls, the PhNR wave saturated amplitude increased as the b + d-wave Vmax increased. This trend was absent in treated marmosets. Conclusions: Marmosets induced with negative defocus exhibit early alterations in inner retinal saturated amplitudes compared to controls, prior to the development of compensatory myopia. These early ERG changes are independent of refraction and eye size and may reflect early changes in bipolar, ganglion, amacrine, or glial cell physiology prior to myopia development. Translational Relevance: The early changes in retinal function identified in the negative lens-treated marmosets may serve as clinical biomarkers to help identify children at risk of developing myopia.

Retinal complications post posterior chamber phakic intraocular lens implantation at a tertiary eye hospital in the Eastern Province of Saudi Arabia.

PURPOSE: Phakic intraocular lenses treat higher degrees of myopia not possible previously with conventional refractive surgery. The aim of this study is to report the incidence and risk factors of retinal complications after posterior chamber PIOL implantation and assess the differences in biometric parameters between patients who developed such complications versus those who did not. METHODS: This retrospective study recruited 514 patients who underwent ICL implantation to correct myopia at a tertiary eye hospital center in the Eastern province of Saudi Arabia. Follow up period was at least one year. Medical records of the patients were reviewed to obtain the required data. Associations between respondents' characteristics and retinal complications were evaluated using the Chi-squared test. RESULTS: The mean (SD) age was 27.7 (± 6.5) years ranging from 18 to 47. Laser treatment was performed in 14 cases (2.7%). Retinal complications occurred in six cases (1.2%). The risk of retinal complication was significantly higher among patients with high axial length (OR = 1.3, 95% CI 1.2, 1.4) and patients with high pre-spherical equivalent before ICL (OR = 1.09, 95% CI 1.03, 1.4). CONCLUSION: Patients with higher axial length and higher pre-spherical equivalent before ICL implantation are at high risk of retinal complications.

Heterogenous thinning of peripapillary tissues occurs early during high myopia development in juvenile tree shrews.

Myopia is an independent risk factor for glaucoma, but the link between both conditions remains unknown. Both conditions induce connective tissue remodeling at the optic nerve head (ONH), including the peripapillary tissues. The purpose of this study was to investigate the thickness changes of the peripapillary tissues during experimental high myopia development in juvenile tree shrews. Six juvenile tree shrews experienced binocular normal vision, while nine received monocular -10D lens treatment starting at 24 days of visual experience (DVE) to induce high myopia in one eye and the other eye served as control. Daily refractive and biometric measurements and weekly optical coherence tomography scans of the ONH were obtained for five weeks. Peripapillary sclera (Scl), choroid-retinal pigment epithelium complex (Ch-RPE), retinal nerve fiber layer (RNFL), and remaining retinal layers (RRL) were auto-segmented using a deep learning algorithm after nonlinear distortion correction. Peripapillary thickness values were quantified from 3D reconstructed segmentations. All lens-treated eyes developed high myopia (-9.8 ± 1.5 D), significantly different (P < 0.001) from normal (0.69 ± 0.45 D) and control eyes (0.76 ± 1.44 D). Myopic eyes showed significant thinning of all peripapillary tissues compared to both, normal and control eyes (P < 0.001). At the experimental end point, the relative thinning from baseline was heterogeneous across tissues and significantly more pronounced in the Scl (-8.95 ± 3.1%) and Ch-RPE (-16.8 ± 5.8%) when compared to the RNFL (-5.5 ± 1.6%) and RRL (-6.7 ± 1.8%). Furthermore, while axial length increased significantly throughout the five weeks of lens wear, significant peripapillary tissue thinning occurred only during the first week of the experiment (until a refraction of -2.5 ± 1.9 D was reached) and ceased thereafter. A sectorial analysis revealed no clear pattern. In conclusion, our data show that in juvenile tree shrews, experimental high myopia induces significant and heterogeneous thinning of the peripapillary tissues, where the retina seems to be protected from profound thickness changes as seen in Ch-RPE and Scl. Peripapillary tissue thinning occurs early during high myopia development despite continued progression of axial elongation. The observed heterogeneous thinning may contribute to the increased risk for pathological optic nerve head remodeling and glaucoma later in life.

Choroidal Morphology and Photoreceptor Activity Are Related and Affected by Myopia Development.

Purpose: The choroid is critical for the regulation of eye growth and is involved in the pathogenesis of myopia-associated ocular complications. This study explores the relationship among choroidal biometry, photoreceptor activity, and myopic growth in marmosets (Callithrix jacchus) with lens-induced myopia. Methods: A total of 34 common marmosets aged 92 to 273 days old were included in this study. Axial myopia was induced in 17 marmosets using negative soft contact lenses and 17 marmosets served as untreated controls. Cycloplegic refraction (RE) and vitreous chamber depth (VCD) were measured using autorefraction and A-scan ultrasonography, respectively. Choroidal scans were obtained using spectral-domain optical coherence tomography and binarized to calculate subfoveal choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), and LA/SA. To assess photoreceptor activity, the a-wave of the full-field electroretinogram was measured. Regression models were used to investigate the relationship between outcome measures. Results: Eyes induced with axial myopia (RE = -7.14 ± 4.03 diopters [D], VCD = 6.86 ± 0.39 mm) showed significant reductions (4.92-21.24%) in all choroidal parameters (ChT, TCA, LA, SA, CVI, and LA/SA) compared to controls (RE = -1.25 ± 0.60 D, VCD = 6.58 ± 0.26 mm, all P < 0.05), which changed as a function of refraction and vitreous elongation, and were associated with a decrease in the a-wave amplitude. Further, multiple regression showed that a combination of ChT and CVI could well predict RE and VCD. Conclusions: This study reports the existence of significant alterations in choroidal morphology in non-human primate eyes induced with myopia. The changes in choroidal anatomy were associated with reduced light-adapted a-wave amplitude. These findings may represent early markers for reduced visual performance and chorioretinal complications known to occur in eyes with large degrees of myopia.

Impact of removing soft contact lenses 1 day versus 1 month before surgery on the outcomes of microkeratome laser in situ keratomileusis.

PURPOSE: To compare the outcomes, safety, efficacy, and predictability of microkeratome laser in situ keratomileusis (LASIK) 24 h and one month or more after removing soft contact lenses. SETTING: ULTRALASIK Eye Center, Dubai, United Arab Emirates. METHODS: The patients were divided based on the time of discontinuation of the soft contact lenses before LASIK (Group 1 at 24 h and Group 2 at one month or longer), and the two groups were well matched. Schirmer's testing, tear break-up time, corrected distance visual acuity, uncorrected distance visual acuity, manifest refraction spherical equivalent, and infection rate were evaluated preoperatively and at one week, one month, and six months after treatment. RESULTS: Group 1 (G1) comprised 1025 eyes, and group 2 (G2) had 1052 eyes. The groups were comparable preoperatively. The overall-mentioned outcomes were comparable between groups with uncorrected distance visual acuity of - 0.084 ± 0.12 logMAR in G1 and - 0.078 ± 0.17 logMAR in the G2 at 6 months (P = 0.322). Tear break-up time as well as Schirmer's testing results was also comparable with no evidence of increased risk of dry eyes or non-inflammatory complications in any of the groups on follow-up visits at 1 week (P = 0.421), 1 month (P = 0.101), and 6 months (P = 0.399) postoperatively. Finally, no infectious complications were recorded in either of the groups. CONCLUSION: With the absence of corneal warpage, no statistical or clinical difference in microkeratome LASIK outcomes and safety was spotted between the groups despite the difference in SCL discontinuation time before the procedure.

Factors Predicting the Need for Re-treatment After Laser Refractive Surgery in Patients With Mixed Astigmatism.

PURPOSE: To identify risk factors that increase the likelihood of re-treatment following refractive surgery in patients with mixed astigmatism. METHODS: This was a retrospective study including patients who underwent either laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between 2000 and 2019 and had mixed astigmatism (spherical error of +0.50 D or greater and spherical equivalent of less than 0.00 diopters [D]). Patients were divided into two groups according to whether they underwent re-treatments during the study period. RESULTS: Overall, 785 eyes (785 patients) were included. In total, 5.2% of the eyes (n = 41) underwent re-treatment. The re-treatment group was more likely to have preoperative high astigmatism (80.5% vs 48.3%, P < .001), moderate to high hyperopia (36.6% vs 22.3%, P = .035), and to have undergone surgery earlier during the study period (P < .001). They were also more likely to have undergone surgery using the Wave-Light EX200 rather than the EX500 laser platform (Alcon Laboratories, Inc) (P < .001), have a treated optical zone of 6 mm rather than 6.5 mm (P < .001 for both), and their maximum ablation depth was greater (P < .001). There was no difference between the re-treatment and control groups regarding procedure type (PRK vs LASIK). Binary logistic regression found preoperative high astigmatism (odds ratio = 3.97, P < .001) and the type of laser platform used (EX200, odds ratio = 7.78, P < .001) as the only independent factors associated with re-treatment. CONCLUSIONS: Re-treatment rates following correction of mixed astigmatism were 5.2% over 20 years. Use of a sixth-generation laser platform significantly reduced the risk of re-treatment. Presence of high astigmatism is a significant risk factor for re-treatment. There was no difference in retreatment risk between PRK and LASIK. [J Refract Surg. 2024;40(2):e73-e78.].

Analysis of factors related to the development of ocular biometric parameters in Chinese children aged 6-10 years: a cross-sectional study.

OBJECTIVES: Emmetropia depends on the precise coordination of ocular biometry, including axial length (AL), corneal curvature, lens thickness and anterior chamber depth (ACD). Disruption of this coordination leads to refractive errors such as myopia. This article aimed to determine the factors affecting ocular biometry and myopia development in young children. DESIGN: A cross-sectional study. SETTING: This study was conducted in a primary school in the Yanqing district of Beijing, China. PARTICIPANTS: 792 students in grades 1-3 without hyperopia (>+2.00 D), strabismus, or amblyopia were selected. EXCLUSIONS: students had conditions affecting best corrected visual acuity and whose guardians refused to provide informed consent. Ocular biometric measurements and non-cycloplegia autorefraction were performed. The questionnaire addressed factors such as perinatal factors and environmental factors. INTERVENTIONS: None. PRIMARY AND SECONDARY OUTCOMES: Ocular biometry and myopia. RESULTS: According to the multivariate logistic regression analysis, electronic screen use >2 hours/day (OR=2.175, p=0.013), paternal myopia (OR=1.761, p=0.002), maternal myopia (OR=1.718, p=0.005), taller height (OR=1.071, p<0.001), maternal education (OR=0.631, p=0.012) and maternal gestational hypertension (OR=0.330, p=0.042) were associated with myopia. AL was affected by female sex (OR=0.295, p<0.001), older age (OR=1.272, p=0.002) and taller height (OR=1.045, p<0.001). Female sex (OR=0.509, p<0.001), taller height (OR=1.046, p<0.001), use of electronic screens >2 hours each day (OR=3.596, p<0.001) and time spent outdoors >2 hours each day (OR=0.431, p=0.001) influenced ACD incidence. Central corneal thickness (CCT) was associated with older age (OR=1.113, p=0.008), paternal education (OR=1.474, p=0.007), premature birth (OR=0.494, p=0.031), history of blue light therapy in infancy (OR=0.636, p=0.041) and history of incubator therapy in infancy (OR=0.263, p=0.009). Only sex influenced corneal curvature. CONCLUSIONS: The factors associated with myopia were partly related to ACD and AL, and perinatal factors were associated with myopia and CCT. TRIAL REGISTRATION NUMBER: ChiCTR2200065398.

Vitamin D and myopia: a review.

Myopia is a worldwide public health problem of vision disorder caused by multiple factors, which has posed a huge socioeconomic burden, raising concerns about sight-threatening ocular complications. Vitamin D, as a kind of fat-soluble vitamin, related to time-spent-outdoors, has been considered by extensive studies to have potential relationship with myopia. We reviewed studies published in a decade which estimated the association of blood vitamin D status with myopia and summarized the universality and individuality of all research articles. Several research articles suggested the known environmental risk factors of myopia, including age, gender, ethnicity, education level, parental and school conditions, time-spent-outdoors, and sunlight exposure, and recent epidemiological studies demonstrate that increased vitamin D levels, by virtue of the extended outdoor time, may be an important modifiable factor and a protective effect that delay the progression of myopia in children and adolescents rather than in adults. The genetic studies have been conducted to get access to the evidence of gene polymorphism for explaining the association of serum vitamin D status and myopia, but the precise genetic interpretation of vitamin D and myopia remains unclear so far; on the other hand, the possible mechanisms are various like copolymerization mechanism, calcium homeostasis and imbalance of ciliary muscle function regulation, but nearly all of the investigators are inclined to remain skeptical. This article reviews the age-related epidemiological proofs, existent genetics correlations, possible underlying biological mechanisms and further values for the protective association between vitamin D and myopia, providing the possibility of prevention or postponement for myopia.

Nutritional intake, environmental factors, and their impact on myopia prevalence in Korean children aged 5-12 years.

BACKGROUND: Myopia is a complex condition influenced by numerous factors, including genetic predisposition, environmental factors, and lifestyle choices. Although evidence indicates that certain dietary factors may influence the development of myopia, this relationship is still not completely understood and is a topic of ongoing research. METHODS: This study analyzed the relationship between dietary habits, environmental factors, and the prevalence of myopia in a sample of 24,345 children aged 5-12 years from the seventh Korea National Health and Nutrition Examination Survey (KNHANES VII). The average daily intake of dietary nutrients associated with the refractive error status of the participants was analyzed using analysis of variance (GLM) and the Scheffe method for post-hoc comparison. Multiple logistic regression analysis was conducted between the participant's refractive error status and daily dietary nutrient intake, while taking into consideration the age, sex, BMI, parental myopia, and near-work hours. RESULTS: The risk of myopia increased with age, especially notable between ages 11 and 12, and was higher in children with both parents having myopia. Dietary factors played a crucial role; children with myopia had significantly lower intake of fat, omega-3 fatty acids, and retinol but higher intake of other nutrients compared to emmetropic and hyperopic counterparts. High consumption of carbohydrates, protein, phosphorus, iron, potassium, and sodium was associated with increased myopia risk. High sodium intake was particularly associated with a 2.05-fold increased myopia risk. CONCLUSIONS: This study highlights the significant role of diet and lifestyle choices in the development of myopia in children. Our findings suggest the importance of considering these specific factors in the management and prevention strategies for myopia, underscoring the need for targeted interventions in children's health and vision care.

Synchronous myopia development induced by bilateral form deprivation in chicks.

Form deprivation (FD) is a widely employed experimental paradigm, typically used to induce unilateral myopia in animal models. This model is weakened by potential influence upon the FD eye from vision in the freely-viewing contralateral eye, which could be eliminated by imposing FD in both eyes; but while a few previous studies have explored the feasibility of inducing bilateral FD in chicks, substantial discrepancies in treatment outcomes were noted. Consequently, this study aimed to establish a bilateral FD myopia model in chicks, with validation by investigating the associated ocular growth patterns, feeding, and social behavior. Six-day-old chicks were treated with bilateral (n = 21) or unilateral (n = 10) FD for 12 days; the fellow untreated eyes in the unilateral FD group served as controls. Refractive error, corneal power, and ocular axial dimensions were measured at 4-day intervals after the onset of form deprivation, with a Hartinger refractometer, a custom-made videokeratography system, and a high-resolution A-scan ultrasonographer, respectively. Body weight was monitored to assess the chick's physical development. Our results showed that birds treated with bilateral FD grew as robustly as the unilaterally form-deprived chicks, with similar or slightly heavier body weights and mortalities. Unilateral FD induced significantly higher myopia in the treated eye, with stronger corneal power, deeper anterior and vitreous chambers, and longer axial length. Moreover, either bilaterally or unilaterally FD eyes developed similar refractive error (bilateral FD, left: -28.03 ± 9.06 D, right: -28.44 ± 9.45 D; unilateral FD: -29.48 ± 8.26 D) and ocular biometric changes; but choroidal thickness was thicker in bilaterally FD eyes, rather than thinner as in unilaterally FD eyes. In addition to the highly synchronized (symmetrical, parallel) development reported previously in bilateral FD, we found in this study that the correlations between bilaterally form-deprived eyes were highest for ocular biometric parameters directly contributing to myopia development, including corneal power (r = 0.74 to 0.93), anterior chamber depth (r = 0.60 to 0.85), vitreous chamber depth (r = 0.92 to 0.94), and axial length (r = 0.90 to 0.96). The remarkably synchronized growth pattern confirmed the feasibility of the bilateral FD paradigm for future research on myopia.

Lens-induced myopization and body weight in young guinea pigs.

BACKGROUND: To investigate the relationship between body weight and Axial length in guinea pigs. METHODS: Forty pigmented guinea pigs were randomly divided into two groups, namely control group and negative lens-induced myopization (LIM) group. After measuring the baseline axial length and body weight (BW), guinea pigs of LIM group received bilateral negative lens-induced myopization using - 10.0 diopters lenses. One week later, the lenses were removed and biometric and ophthalmoscopic examinations were repeated. RESULTS: Two groups of guinea pigs showed no statistical difference in initial body weight and eye axis length. Compared to the control group, the lens-induced group had a lower weight (P = 0.02) and a longer axial length (P < 0.01) at the end of study Neither at baseline nor at week 1 did AL correlate with BW in both groups (Control Baseline: r = 0.306, P = 0.19; Control Week1: r = 0.333, P = 0.15; LIM Baseline: r=-0.142, P = 0.55; LIM Week 1: r = 0.189, P = 0.42). Lens-induction had a significant effect on axial elongation (P < 0.01) while body weight had no impact on such aspect (P > 0.05). CONCLUSION: In guinea pigs of the same age, axial length was not correlated with body weight. Also, baseline body weight had no impact on natural axial length growth or lens-induced myopia. Lens-induction caused a significant reduction in body weight gain.

A Mendelian randomization study on the causal relationship between smoking, alcohol consumption, and the development of myopia and astigmatism.

The influence of environmental factors like smoking and alcohol on myopia and astigmatism is controversial. However, due to ethical concerns, alternative study designs are urgently needed to assess causal inference, as mandatory exposure to cigarettes and alcohol is unethical. Following comprehensive screenings, 326 single nucleotide polymorphisms (SNPs) related to myopia and astigmatism were included in the dataset. To validate the causal association between exposures such as cigarette smoking, alcohol consumption, and coffee intake, and outcomes namely astigmatism and myopia, five regression models were employed. These models encompassed MR-Egger regression, random-effects inverse-variance weighted (IVW), weighted median estimator (WME), weighted model, and simple model. The instrumental variables utilized in these analyses were the aforementioned SNPs. Apply Cochran's Q test to determine heterogeneity of SNPs; if heterogeneity exists, focus on IVW model results. The IVW model showed a 1.379-fold increase in the risk of astigmatism (OR = 1.379, 95%CI 0.822~2.313, P = 0.224) and a 0.963-fold increase in the risk of myopia (OR = 0.963, 95%CI 0.666~1.393, P = 0.841) for each unit increase in smoking. For each unit increase in coffee intake, the risk of astigmatism increased 1.610-fold (OR = 1.610, 95%CI 0.444~5.835, P = 0.469) and the risk of myopia increased 0.788-fold (OR = 0.788, 95%CI 0.340~1.824, P = 0.578). For each additional unit of alcohol consumption, the risk of astigmatism increased by 0.763-fold (OR = 0.763, 95%CI 0.380~1.530, P = 0.446), and none of the differences were statistically significant. However, for each unit of alcohol consumption, the risk of myopia increased by 1.597 times, and the difference was statistically significant (OR = 1.597, 95%CI 1.023~2.493, P = 0.039). The findings indicate that alcohol consumption is a risk factor for myopia but smoking and coffee intake do not affect its development. Additionally, there is no association between smoking, alcohol consumption, coffee intake, and the risk of astigmatism.

Effect modification of time spent outdoors on the association between early childhood overweight and myopia: a one-year follow-up study.

BACKGROUND: This study examined the moderating role of outdoor time on the relationship between overweight and myopia. METHODS: The data for this study was obtained from a prospective study in Shanghai, where non-myopic children wore wristwear and were followed up for 1 year. Eye examinations were performed at each visit. The modification effect was assessed on the additive scale using multivariable logistic regression, and relative excess risk due to interaction was used to calculate the modification effect. RESULTS: A total of 4683 non-myopic children were included with 32.20% being overweight at baseline. Following a 1-year period, 17.42% of children had myopia. When compared to those who spent <90 minutes outdoors, children who spent >120 had a relative risk of myopia onset that was reduced to 0.61. As time spent outdoors decreased, more risks of myopia onset were identified among overweight children than among normal children, the modification effect on the additive scale was -0.007, with ~70% of this effect attributed to the modifying influence of outdoor time. CONCLUSIONS: Increasing outdoor time can reduce myopia more among overweight children than normal. Future interventions should focus on outdoor activities among overweight children to reduce myopia risks.

Association of 10 Genetic Variations and 10 Environmental Factors with Myopia of Different Severities in Different Age Groups of People in Northeast China.

BACKGROUND: To investigate the association of 10 genetic variations and 10 environmental factors with myopia of different severities in different age groups of children and adolescents in northeast China. METHODS: Parental history and genetic testing for myopia-related susceptibility genes were carried out in a cohort of children and adolescents aged 2-17 years. In addition, 10 single nucleotide polymorphism (SNP) sites for genotyping and 10 environmental risk factors were selected, and the differences between site variation and environmental factors in different age groups with different degrees of myopia were explored. RESULTS: A total of 2497 volunteers were recruited, including 2023 myopes and 474 non-myopes in the control group. From the cohort, 1160 subjects were sequenced for myopia SNP sites. Compared with the non-myopic group, the myopia of parents, outdoor activity less than 60 min per day, and a high-sugar diet were risk factors for developing myopia. Two syntrophin beta 1 (SNTB1) sites, rs4455882 and rs6469937 were found to be significantly associated with moderate myopia; fibroblast growth factor 10 (FGF10) rs339501 was significantly correlated with high myopia; and insulin-like growth factor 1 (IGF1) rs5742714 was significantly correlated with different degrees of myopia in the age group of <6 years. Finally, the FGF10 gene rs339501 SNP was significantly associated with moderate myopia and mild myopia in the 6- to 12-year-old age group. CONCLUSIONS: Our results indicate that myopia is affected by both environmental and genetic factors. To prevent and control myopia, attention should be paid to the parental history of myopia, a high-sugar diet should be avoided, and outdoor time should be adjusted according to the average daily sunshine. In addition, it is necessary to pay attention to the increased risk of myopia in school-age children caused by SNTB1 rs4455882, FGF10 rs339501, and IGF1 rs5742714.

National estimate and associated factors of myopia among schoolchildren in Ethiopia: A systematic review and meta-analysis.

INTRODUCTION: Myopia is a global public health concern that has a significant socioeconomic and psychological impact on schoolchildren. If Myopic patients are not detected early, they are exposed to retinal detachment, cataracts, and glaucoma. There have been previous studies conducted in Ethiopia, but there is significant inconsistency among studies. Hence, the aim of this study was to provide a single figure as well as associated factors for Myopia among Ethiopian schoolchildren. METHOD: The national and international databases and gray literature were searched for important research articles. This review included school-based cross-sectional studies that were reported in English. The data were extracted using Microsoft word and exported to Stata™ Version 17.0 statistical software for further management and analysis .The presence of heterogeneity was checked using Cochrane Q test via fixed effects model and presented by forest plots with 95% CI. Due to the presence of substantial heterogeneity, I2 test using random effects model was computed to estimate the effect size. The existing heterogeneity among studies was explained by regional difference. To identify factors associated with myopia, meta regression was computed and significant factors was reported using OR with 95% CI. RESULTS: In this systematic review and meta-analysis, 12 studies with a total of 9688 schoolchildren were included. The national estimate of myopia among schoolchildren in Ethiopia was 6.49% (95%CI: 4.86, 8.12). Having family history of myopia (OR: 9.18, 95%CI: 3.5,24.02) and being female (OR: 0.94, 95% CI: 0.50, 0.98) were the identified factors associated with myopia. CONCLUSION: Myopia is one of the most prevalent childhood health condition in Ethiopia, which affects about one in every fourteen schoolchildren. Schoolchildren who had family history of myopia and being female were the identified risk factors of myopia among schoolchildren. Clinical and public engagement activities are needed to address the burden of myopia.

Association between body mass index and myopia in the United States population in the National Health and Nutrition Examination Surveys 1999 to 2008: a cross-sectional study.

BACKGROUND: This study investigated the association between body mass index (BMI) and myopia in the United States. METHODS: This cross-sectional study included 8,000 participants from the 1999 to 2008 National Health and Nutrition Examination Survey (NHANES). BMI was classified into four groups: < 18.5, 18.5 - 24.9, 25-29.9, and > 29.9. Three diagnostic thresholds were used for myopia A\B\C: spherical equivalent ≤ -0.5\-0.75\-1 diopters in the right eye. Multivariate logistic regression analysis and smooth curve fitting were performed to evaluate the association between BMI and myopia. RESULTS: The incidence of myopia was 39.4%. BMI was correlated with myopia, with each 1 kg/m2 increase in BMI associated with a 1% increase in the risk of myopia (OR, 1.01; 95% CI 1.01 1.02; p < 0.05). In myopia B, after adjusting for confounding factors, compared with the reference group (BMI 18.5-24.9), participants with a BMI of 25-29.9 and greater than 29.9 had a 14% and 25% increased risk of myopia, respectively (OR 1.14; 95% CI 1.01 1.29; p = 0.037, OR 1.25; 95% CI 1.08 1.44; p = 0.003), which was similar to the results for myopic A (OR, 1.15; 95% CI 1.02 1.3; p = 0.027, OR 1.19; 95% CI 1.03 1.37; p = 0.018) and myopia C (OR 1.15; 95% CI 1.01 1.31; p = 0.035, OR 1.18; 95% CI 1.01 1.37; p = 0.032). Moreover, there was a linear relationship between myopia and BMI (p for nonlinearity = 0.767). CONCLUSIONS: Myopia using all three diagnostic thresholds was positively associated with higher BMI. This suggests a potential association between myopia and higher BMI in the American population, warranting further investigations.

[Outbreak of myopia in pediatrics : management, prevention and treatment]. / Épidémie de myopie en pédiatrie : prise en charge, prévention et traitement.

The worldwide incidence and prevalence of myopia has increased. The age of onset of this refractive disorder has inversely decreased. In addition to genetic and familial factors, environmental factors related to a sedentary lifestyle and activities in highly solicited near vision seem to have an impact on the development of axial myopia, that is an early and non-reversible elongation of the eyeball. Prevention of the development of myopia in pediatrics through simple daily measures plays therefore a fundamental role. In addition, pharmacological treatments, and specific optical treatments for controlling myopia have shown encouraging results in reducing the risk of long-term complications of progressive myopia, that is increased risk of developing cataract, glaucoma, retinal detachment, or maculopathy.

L'incidence et la prévalence mondiales de la myopie ont augmenté. L'âge de survenue de ce trouble réfractif a quant à lui diminué. Outre les facteurs génétiques et familiaux, des facteurs environnementaux liés à la sédentarité et aux activités en vision proche hautement sollicitée semblent avoir un impact sur le développement de la myopie axile, c'est-à-dire une élongation précoce et non réversible du globe oculaire. La prévention du développement de la myopie par des mesures quotidiennes simples joue donc un rôle fondamental. En outre, des traitements pharmacologiques et par moyens auxiliaires spécifiques dits « freinateurs ¼ ont montré des résultats encourageants pour diminuer le risque de complications à long terme de la myopie progressive, tels qu'un risque augmenté de développer une cataracte, un glaucome, un décollement de rétine ou une maculopathie.