Ocular and systemic associations and heritability of retinal arterial wall-to-lumen ratios in a twin cohort.

PURPOSE: To investigate ocular and systemic factors associated with the retinal arterial wall-to-lumen ratio (WLR) and to determine the relative contribution of genetic and environmental variation to WLR in healthy adults. METHODS: This cross-sectional twin study included 78 monozygotic and 67 dizygotic same-sex twin pairs aged 58.4 ± 9.8 (mean ± SD) years. Lumen diameter (LD) and outer diameter (OD) of a superotemporal retinal artery were measured using adaptive optics fundus photography, and the WLR was calculated. Linear mixed model regression analysis of associations with WLR comprised the descriptive variables ocular axial length (AL), intraocular pressure (IOP), height, weight, body mass index (BMI), smoking, blood pressure, high density (HDL), low density (LDL) and very low density (VLDL) lipoproteins, total cholesterol and triglycerides. The relative influence of genes and environment on WLR was calculated through polygenetic modelling. RESULTS: Increasing age and arterial blood pressure were associated with a higher WLR, while increasing retinal artery OD and ocular AL were associated with a lower WLR. Sex, smoking status, BMI, IOP, cholesterol levels or triglycerides had no detectable impact on the WLR. Broad-sense heritability of WLR was 21% (95% CI: 1-41%), while environmental factors accounted for the remaining 79% of the interindividual variance (95% CI: 59-99%). CONCLUSION: Retinal artery wall thickness was closely linked to increasing age and higher arterial blood pressure, the latter being mediated by the environment over genes.

Smoking in pregnancy is associated with increased adiposity and retinal arteriolar wall-to-lumen ratio in adolescence: The Copenhagen Child Cohort Study 2000.

PURPOSE: To investigate the association between prenatal exposures and anthropometric data and cardiovascular risk factors including retinal arteriolar wall-to-lumen ratio in adolescence. METHODS: This longitudinal observational study included all 1445 adolescents from the Copenhagen Child Cohort 2000 who attended the 2016-2017 examination. Outcome measures included retinal arteriolar wall-to-lumen ratio, height, body mass index, waist-to-hip ratio, body composition measured by bioimpedance, and blood pressure. Information on prenatal exposures (birth weight, gestational age, maternal smoking during pregnancy) as well as sex, parental age, household income and parental educational levels were obtained from national registries. Associations between exposures and outcome measures were analyzed using general linear models. RESULTS: Maternal smoking during pregnancy was associated with a higher retinal arteriolar wall-to-lumen ratio (0.004 or 1.9%, P = 0.009) at age 16/17 years, an association driven exclusively by the female participants (0.008 or 3.7%, P < 0.0001). Maternal smoking during pregnancy was also associated to higher body-mass index (1.43 kg/m2, P < 0.0001), waist-to-hip ratio (0.02, P < 0.0001) and fat mass index (0.93 kg/m2, P < 0.0001). Birth weight, gestational age, and parental age had no detectable impact on retinal arteriolar wall-to-lumen ratios. CONCLUSION: Prenatal exposure to tobacco smoking is associated with a higher risk of obesity and, predominantly in girls, to a greater retinal arteriolar wall thickness, which suggests that maternal smoking may induce an unfavorable cardiovascular and metabolic risk profile in the child.

Cone photoreceptor density in the Copenhagen Child Cohort at age 16-17 years.

PURPOSE: To examine cone density in relation to gestational and morphological parameters in the Copenhagen Child Cohort (CCC2000). METHODS: The macula was imaged using adaptive optics in 1,296 adolescents aged 16-17 years. Axial length and distance visual acuity were determined. Absolute and angular cone photoreceptor density were analysed for an 80 × 80-pixel area, 2 degrees temporal to the fovea. Association with axial length was analysed with linear regression. Correlation with visual acuity was described with a Pearson correlation coefficient. Associations of cone density with gestational parameters, maternal smoking, sex and age were analysed using multiple regression adjusted for axial length. RESULTS: Mean absolute cone density was 30,007 cones/mm2 (SD ± 3,802) and mean angular cone density was 2,383 cones/deg2 (SD ± 231). Peri- and postnatal parameters, sex and age had no statistically significant effect on cone density (p > 0.05). Absolute cone density decreased with longer axial length (-2,855 cones/mm2 per mm or -9.7% per mm, p < 0.0001). For angular density, which included a correction for the geometrical enlargement of the eye with axial length, a decrease with axial length was detectable, but it was small (-20 cones/deg2 per mm or -0.84% per mm, p = 0.009). CONCLUSIONS: The decrease in cone density per unit solid angle with increasing axial length was small, less than 1 percent per mm, indicating that expansion of the posterior pole during the development of refraction takes place without a clinically significant loss of cones. Perinatal parameters, within the spectrum presented by the study population, had no detectable effect on cone density.

Retinal arteriolar wall-to-lumen ratios at 16-17 years in the Copenhagen Child Cohort 2000 Study.

PURPOSE: To study the thickness of retinal arteriolar walls in a population-based cohort of adolescents. METHODS: This cross-sectional, observational study included 1217 participants aged 16-17 years from the Copenhagen Child Cohort 2000 Study. The wall thickness and lumen diameter of a major branch retinal arteriole were measured using adaptive optics imaging. The wall-to-lumen ratio was analyzed in relation to blood pressure and body composition variables using a general linear model. Overall in the study population, wall-to-lumen ratio was found to decrease by 0.49% per µm increase in arteriole diameter (P < 0.0001) and all subsequent analyzes were adjusted accordingly. RESULTS: The average outer and inner arteriole diameters were 117 ±â€Š19 and 96.6 ±â€Š18 µm (mean ±â€ŠSD), corresponding to a wall-to-lumen ratio of 0.21 ±â€Š0.024. There was no detectable difference between sexes. A higher wall-to-lumen ratio was associated with a higher BMI (+0.21% per kg/m, P = 0.0018), higher body fat percentage (+0.097% per 1% increase, P = 0.0052), wider hip circumference (+1.1% per 10 cm increase, P = 0.0006), wider waist circumference (+0.92% per 10 cm increase, P = 0.0009), higher SBP in girls (+1.1% per 10 mmHg increase, P = 0.0005), longer axial length (+0.70% per mm increase, P = 0.013), and younger age (+4.9% per year younger, P < 0.0001), adjusted for arteriole diameter, age, sex, and height. CONCLUSION: A higher retinal arteriolar wall-to-lumen ratio was associated with all registered indices of body fat proportion.

Low physical activity and higher use of screen devices are associated with myopia at the age of 16-17 years in the CCC2000 Eye Study.

PURPOSE: To determine the myopia prevalence in a Danish cohort aged 16-17 years and its relation to physical activity and use of screen-based electronic devices. METHODS: The Copenhagen Child Cohort 2000 Eye Study is a prospective, population-based, observational study. Information about use of screen devices and physical activity was obtained using questionnaires. Myopia was defined as non-cycloplegic subjective spherical equivalent refraction ≤-0.50 D in right eye. RESULTS: We included 1443 participants (45% boys) with a median age (±IQR) of 16.6 years (±0.3). The prevalence of myopia was 25% (CI95% 23-28, n = 360) with no differences between sexes (p = 0.10). The odds ratio (OR) for myopia was 0.57 (CI95% 0.42-0.76, p = 0.0002) in participants physically active 3-6 hr/week (n = 502) and 0.56 (CI95% 0.42-0.76, p = 0.0002) if active >6 hr/week (n = 506), both compared with participants physically active <3 hr/week (n = 396). The use of screen devices >6 hr/day was associated with increased OR for myopia compared with screen device use <2 hr/day in both weekdays (OR = 1.95, CI95% 1.16-3.30, p = 0.012) and weekends (OR = 2.10, CI95% 1.17-3.77, p = 0.013). CONCLUSION: In this cohort of healthy 16-17-year olds, lower physical activity and more use of screen devices contributed significantly to the observed 25% prevalence of myopia with a roughly doubled risk of having myopia if physically active <3 hr/week or if using screen devices >6 hr/day. Our results support physical activity being a protective factor and near work a risk factor for myopia in adolescents.