Association between serum 25-hydroxyvitamin D levels and myopia in general Korean adults

The response of the retinal vessels to the vitamin D supplementation treatment running title: The retinal vessels and vitamin D supplementation treatment

BACKGROUND

We planned to prospectively investigate the response of retinal microvasculature to vitamin D supplementation treatment.

METHODS

This study was designed as a prospective, longitudinal study. We enrolled healthy adults with vitamin D deficiency. Baseline optical coherence tomography angiography parameters compared after vitamin D supplementation treatment.

RESULTS

In the treated group, the mean whole, parafoveal, and perifoveal vessel density in deep capillary plexus were significantly reduced compared to the baseline (p = 0.019, p = 0.023, p = 0.012, respectively). Additionally, the final whole, parafoveal, and perifoveal vessel density in deep capillary plexus were inversely related to the vitamin D changes (Spearman's rho:-0.516, p = 0.024; Spearman's rho:-0.524, p = 0.019; Spearman's rho:-0.569, p = 0.012, respectively). Vascular parameters did not change in the untreated group compared to the baseline.

CONCLUSION

Although the effects of some confounding factors, such as exposure time to sunlight and dietary vitamin D intake in the study, were not yet known, vitamin D supplementation therapy appeared to affect retinal microvasculature. Optic coherence tomography angiography might indicate noninvasively the effectiveness or sufficiency of vitamin D treatment at the microvascular level, although the observed changes in the retinal vessels are as yet not fully understood.

Biomarkers: Promising Tools Towards the Diagnosis, Prognosis, and Treatment of Myopia

The prevalence of myopia, especially high myopia, continues to increase in several parts of the world. Thus, the use of biomarkers for early myopia detection would be highly valuable for clinical practice aiding in the prevention and myopia control management. The identification of biomarkers that can predict the risk of myopia development, severity of myopia, and treatment response are of paramount significance. In this review, we present the current state of research on biomarkers and myopia, highlighting the challenges and opportunities in biomarkers research for myopia. Although myopia biomarkers may have a role as early indicators of myopia or treatment response, the adoption of biomarkers into myopia clinical practice may only be done when tests have high accuracy, are easily measurable, minimally invasive, and acceptable to parents, children, and eye care professionals. Large consortia studies are necessary to validate biomarkers and translate evidence into clinical practice.

Association Between Serum Vitamin D Levels and Myopia in the National Health and Nutrition Examination Survey (2001-2006)

PURPOSE

To assess the relationship between serum vitamin D levels and myopia in people aged 12-50 years using the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

Demographics, vision, and serum vitamin D levels from NHANES (2001-2006) were analyzed. Multivariate analyses were performed to examine the relationship between serum vitamin D levels and myopia while controlling for sex, age, ethnicity, education level, serum vitamin A, and poverty status. The main outcome was presence or absence of myopia, defined as a spherical equivalent of -1 diopters or more.

RESULTS

Of the 11669 participants, 5,310 (45.5%) had myopia. The average serum vitamin D concentration was 61.6 ± 0.9 nmol/L for the myopic group and 63.1 ± 0.8 nmol/L for the non-myopic group (p = .01). After adjusting for all covariates, having higher serum vitamin D was associated with lower odds of having myopia (odds ratio 0.82 [0.74-0.92], p = .0007). In linear regression modeling that excluded hyperopes (spherical equivalent > +1 diopters), there was a positive relationship between spherical equivalent and serum vitamin D levels. Specifically, as serum vitamin D doubled, spherical equivalent increased by 0.17 (p = .02) indicating a positive dose-response relationship between vitamin D and myopia.

CONCLUSIONS

Participants with myopia, on average, had lower serum concentrations of vitamin D compared to those without myopia. While further studies are needed to determine the mechanism, this study suggests that higher vitamin D levels are associated with lower incidence of myopia.

Association between serum 25-hydroxyvitamin D level and myopia in children and adolescents: a cross-sectional study

BACKGROUND

Prior reports have indicated an inconsistent relationship between vitamin D levels and myopia in children and adolescents with limited sample size. This study was undertaken to further clarify this relationship with a repeated cross-section study.

METHODS

The National Health and Nutrition Examination Survey (NHANES) database with samples <19 years old was utilized. Data on rates of myopia (spherical equivalent less than or equal to -1.0 D), serum 25-hydroxyvitamin D [25(OH)D] level (high performance liquid chromatography), and other key variables were extracted and analyzed. Three models were utilized to evaluate the dose response of vitamin D levels using stepwise logistic regression. Logistic regressions for sex subgroups and other covariates were also performed, and Forest plots were drawn.

RESULTS

Data were available from 6,814 children (49.5% girls; mean age: 14.9±1.85 years). The myopia and non-myopia differed in serum 25(OH)D level, gender, race, poverty income ratio (PIR), and body mass index (BMI). Serum 25(OH)D levels were negatively correlated with myopia [odds ratio (OR) =0.98, 95% confidence interval (CI): 0.77-0.99, P<0.05] regardless of sex. Although the relationship did not appear to be linear, there was a dose effect with higher serum 25(OH)D levels linked with lower rates of myopia. In addition, rates of myopia were increased in females compared with males (OR =1.12, 95% CI: 1.01-1.24, P=0.03), those with a high PIR (OR =1.08, 95% CI: 1.04-1.11, P<0.001), and those with high BMI (OR =1.19, 95% CI: 1.11-1.27, P<0.001). White ethnicity (OR =0.78, 95% CI: 0.68-0.90, P<0.001) and leisure-time exercise (OR =0.94, 95% CI: 0.92-0.97, P=0.02) were associated with lower rates of myopia.

CONCLUSIONS

These findings indicate that higher serum 25(OH)D levels and increased amounts of leisure-time exercise are associated with lower rates of myopia in this group of children and adolescents. Meanwhile, female gender, high PIR level, and high BMI were associated with greater rates of myopia. The findings indicated that children and adolescents needed leisure-time exercise to lower the risk of myopia.

Calcipotriol Attenuates Form Deprivation Myopia Through a Signaling Pathway Parallel to TGF-β2-Induced Increases in Collagen Expression

Purpose

To determine the role of calcipotriol, a vitamin D3 analogue, in myopia development and altering the expression of scleral α1 chain of type I collagen (Col1α1) in mice. We also aimed to identify if the signaling pathway mediating the above changes is different from the one involved in transforming growth factor β2 (TGF-β2)-mediated increases of COL1A1 in cultured human scleral fibroblasts (HSFs).

Methods

C57BL/6J mice were either intraperitoneally injected with calcipotriol and subjected to form deprivation (FD) or exposed to normal refractive development for 4 weeks. Scleral vitamin D receptor (Vdr) expression was knocked down using a Sub-Tenon's capsule injection of an adeno-associated virus-packaged short hairpin RNA (AAV8-shRNA). Refraction and biometric measurements evaluated myopia development. A combination of knockdown and induction strategies determined the relative contributions of the vitamin D3 and the TGF-β2 signaling pathways in modulating COL1A1 expression in HSFs.

Results

Calcipotriol injections suppressed FD-induced myopia (FDM), but it had no significant effect on normal refractive development. AAV8-shRNA injection reduced Vdr mRNA expression by 42% and shifted the refraction toward myopia (-3.15 ± 0.99D, means ± SEM) in normal eyes. In HSFs, VDR knockdown reduced calcipotriol-induced rises in COL1A1 expression, but it did not alter TGF-β2-induced increases in COL1A1 expression. Additionally, TGF-β2 augmented calcipotriol-induced rises in COL1A1 expression. TGF-β receptor (TGFBRI/II) knockdown blunted TGF-β2-induced increases in COL1A1 expression, whereas calcipotriol-induced increases in VDR and COL1A1 expression levels were unaltered.

Conclusions

Scleral vitamin D3 inhibits myopia development in mice, potentially by activating a VDR-dependent signaling pathway and increasing scleral COL1A1 expression levels.

Association between serum vitamin D and refractive status in United States adolescents: A cross-sectional study

Purpose

We performed this study to determine the relationship between serum vitamin D levels and refractive status in adolescents aged 12-19 years.

Methods

Cross-sectional study using the National Health and Nutrition Examination Survey (NHANES) database from 2001 to 2006. We used weighted multivariate linear regression models to assess the association between serum vitamin levels and adolescent refractive status and then built a smooth curve fitting to investigate their internal non-linear relationships. Finally, subgroup analysis was performed according to gender, and the threshold effect of serum vitamin D levels on spherical equivalent degree was analyzed using a two-piecewise linear regression model.

Result

A total of 5,901 adolescents aged 12 to 19 years were included in this study. After adjusting for all confounding factors, the multiple linear regression model showed no significant correlation between adolescent spherical equivalent degree and serum vitamin D [0.0019 (-0.0018, 0.0046)]. However, smooth curve fitting analysis showed an inverted U-shaped curve relationship between spherical equivalent degree and serum vitamin D levels in adolescents (turning point: 58.1 nmol/L). In analyses by gender subgroup, this inverted U-shaped relationship was found to be more pronounced in female adolescents (turning point: 61.6 nmol/L).

Conclusion

Our results suggest that the correlation between refractive status and serum vitamin D in adolescents differs by gender. When serum vitamin D concentrations were <61.6 nmol/L in female adolescents and <53.2 nmol/L in male adolescents, the spherical equivalent degree showed a positive correlation with serum vitamin D levels. However, there was no significant correlation when adolescent vitamin levels exceeded this threshold.

Vitamin D, the Vitamin D Receptor, Calcitriol Analogues and Their Link with Ocular Diseases

The global prevalence of eye diseases continues to grow, bringing with it a reduction in the activity levels and quality of life of patients, and partial or complete blindness if left untreated. As such, there is considerable interest in identifying more effective therapeutic options and preventive agents. One such agent is vitamin D, known to have a range of anti-cancer, anti-angiogenic, anti-inflammatory and anti-oxidative properties, and whose deficiency is linked to the pathogenesis of a range of cardiovascular, cancer, and inflammatory diseases. This review presents the current stage of knowledge concerning the link between vitamin D and its receptor and the occurrence of eye disease, as well as the influence of analogues of calcitriol, an active metabolite of vitamin D. Generally, patients affected by various ocular disorders have vitamin D deficiency. In addition, previous findings suggest that vitamin D modulates the course of eye diseases and may serve as a marker, and that its supplementation could mitigate some disorders. However, as these studies have some limitations, we recommend further randomized trials to clarify the link between vitamin D and its activity with eye disease.

Vitamin D and Ocular Diseases: A Systematic Review

The contributory roles of vitamin D in ocular and visual health have long been discussed, with numerous studies pointing to the adverse effects of vitamin D deficiency. In this paper, we provide a systematic review of recent findings on the association between vitamin D and different ocular diseases, including myopia, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), dry eye syndrome (DES), thyroid eye disease (TED), uveitis, retinoblastoma (RB), cataract, and others, from epidemiological, clinical and basic studies, and briefly discuss vitamin D metabolism in the eye. We searched two research databases for articles examining the association between vitamin D deficiency and different ocular diseases. One hundred and sixty-two studies were found. There is evidence on the association between vitamin D and myopia, AMD, DR, and DES. Overall, 17 out of 27 studies reported an association between vitamin D and AMD, while 48 out of 54 studies reported that vitamin D was associated with DR, and 25 out of 27 studies reported an association between vitamin D and DES. However, the available evidence for the association with other ocular diseases, such as glaucoma, TED, and RB, remains limited.

Low Serum Vitamin D Is Not Correlated With Myopia in Chinese Children and Adolescents

Purpose

This cross-sectional study investigated the association between serum 25-hydroxyvitamin D [25(OH)D] concentration and myopia in two groups of Chinese children aged 6–14 years from different geographic and economic locations.

Methods

A total of 294 children from a lowland area and 89 from a highland area were enrolled as two groups of study subjects. The visual acuity, ocular biometry, and automated refraction were measured. The serum level of 25(OH)D was determined by chemiluminescence immunoassay. Near vision and outdoor exposure durations were assessed with a questionnaire interview. Data were analyzed for differences using Chi-square and Wilcoxon rank sum tests. The risk factors were evaluated using logistic regression analysis.

Results

We found that the serum level of 25(OH)D of the subjects from lowland area was 20.9 ng/mL which was higher than that of subjects from highland area (16.9 ng/mL). The median spherical equivalent refraction (SER) was −0.25 diopters(D) in lowland subjects and −0.63D in highland subjects. The prevalence of myopia was 45.2% in lowland subjects and 55.1% in highland subjects. The average axial length was similar, 23.6 mm and 23.1 mm in lowland and highland subjects, respectively. We found no statistical difference between the average SER and serum 25(OH)D concentration in subjects of either lowland or highland area. The ratio of myopia to non-myopia was also similar in subjects with three levels (sufficient, deficient, and insufficient) of serum 25(OH)D in these two areas.

Conclusions

There is no association between serum 25(OH)D concentration and myopia in the 6–14 years old Chinese children.