Myopic axial elongation in school children and the COVID-19 lockdown in Russia: The Ural Children Myopia Study

The CroMyop study: myopia progression in Croatian children and adolescents-a 15-year retrospective analysis

Purpose

Myopia is a major global health issue, especially among children and adolescents. Understanding its traits and progression is vital for proper management and prevention. This study aimed to fill a gap in research by analyzing demographic and refractive data concerning myopia among children and adolescents in Croatia, with the goal of providing insights into myopia prevalence, progression rates, and associated risk factors within the Croatian population.

Design

This retrospective study utilized a comprehensive dataset from pediatric ophthalmology clinics at the University Eye Department, University Hospital "Sveti Duh," Zagreb, Croatia. The dataset included electronic medical records spanning from January 2008 to July 2023, encompassing demographic and refractive data.

Methods

Data analysis focused on individuals aged 4 to 18 years who were diagnosed with primary myopia and/or compound myopic astigmatism. Ophthalmic examinations, including visual acuity tests, cycloplegic refraction, and assessments for eye comorbidities, were conducted by experienced pediatric ophthalmologists. Statistical analysis, including t-tests, survival analysis, and logistic regression, was performed to assess myopia prevalence, progression rates, and associated factors. These analyses were adjusted for covariates such as age, parental myopia, and gender.

Results

The study included 895 individuals, 51 premyopes, 813 low myopes, and 31 high myopes. The average age of diagnosis was 11.37 ± 3.59 years for premyopes, 11.18 ± 3.53 years for low myopes, and 11.44 ± 4.35 years for high myopes. The fastest progression occurred in 2021 and 2022, -0.5 ± 0.12 D/y for premyopes and - 0.45 ± 0.1 D/y for low myopes. Premyopic progression to low myopia was associated with age 7-9 years (HR 2.42, 1.53 to 3.21) and both parents being myopic (HR 920.27. 850.16 to 950.53). Low myopic individuals with both myopic parents displayed the fastest 11-24 months after first visit progression rates, -0.69 (-0.52 to -0.87) D/y, while the 7-9 age group demonstrated -0.36 (-0.24 to -0.45) D/y. Low myopes aged 7-9 years with baseline SE between -6 D and -4 D were more strongly associated with ≤ - 0.5 D progression (OR = 2.0, 95% CI -1.00 to 2.39).

Conclusion

This study highlights the importance of environmental factors, genetics, and age in addressing myopia progression among Croatian youth, urging further research for effective local intervention strategies.

Prevalence and associated factors of myopia in children and adolescents in Russia: the Ural Children Eye Study

BACKGROUND

To assess the prevalence of myopia and the distribution of ocular axial length as surrogate for myopic refractive error in school children in a population in Russia.

METHODS

The Ural Children Eye Study, a school-based case-control study, was conducted in Ufa/Bashkortostan/Russia from 2019 to 2022 and included 4933 children (age: 9.7±2.6 years; range: 6.2-18.8 years). The parents underwent a detailed interview and the children an ophthalmological and general examination.

RESULTS

Prevalence of any myopia (≤-0.50 dioptres (D)), minor myopia (-0.50 D to -1.0 D), moderate myopia (-1.01 D to -5.99 D) and high myopia (≤-6.0D) was 2187/3737 (46.2%; 95% CI 44.8% to 48.6%), 693/4737 (14.6%; 95% CI 13.6% to 15.6%), 1430/4737 (30.2%; 95% CI 28.9% to 31.5%) and 64/4737 (1.4%; 95% CI 1.0% to 1.7%), respectively. In the children aged 17+ years, prevalence of any, minor, moderate and high myopia was 170/259 (65.6%; 95% CI 59.8% to 71.5%), 130/259 (50.2%; 95% CI 44.1% to 56.3%), 28/259 (10.8%; 95% CI 7.0% to 14.6%) and 12/259 (4.6%; 95% CI 2.1% to 7.2%), respectively. After adjusting for corneal refractive power (beta: 0.09) and lens thickness (beta: -0.08), larger myopic refractive error was associated (r2=0.19) with older age (beta: 0.33), female sex (beta: 0.04), higher prevalence of maternal (beta: 0.15) and paternal (beta: 0.12) myopia, more time spent in school, with reading books or playing with the cell phone (beta: 0.05) and less total time spent outdoors (beta: 0.05). Axial length and myopic refractive error increased by 0.12 mm (95% CI 0.11 to 0.13) and -0.18 D (95% CI 0.17 to 0.20), respectively, per year of age.

CONCLUSIONS

In this ethnically mixed urban school children population from Russia, prevalence of any myopia (65.6%) and high myopia (4.6%) in children aged 17+ years was higher than in adult populations in the same region and it was lower than in East Asian school children, with similar associated factors.

Associations between axial length, corneal refractive power and lens thickness in children and adolescents: The Ural Children Eye Study

PURPOSE

To assess relationships between ocular biometric parameters in dependence of age and sex in children and adolescents.

METHODS

In the Ural Children Eye Study, a school-based cohort study, 4933 children underwent an ophthalmological and general examination.

RESULTS

Complete biometric measurements were available for 4406 (89.3%) children. Cycloplegic refractive error (mean: -0.87 ± 1.73 diopters (D); median: -0.38 D; range: -19.75 D to +11.25 D) increased (multivariable analysis; r2  = 0.73) with shorter axial length (β: -0.99; non-standardized regression coefficient B: -1.64; 95% CI: -1.68, -1.59) and lower corneal refractive power (β: -0.55; B: -0.67; 95% CI: -0.70, -0.64), in addition to higher cylindrical refractive error (β: 0.10; B: 0.34; 95% CI: 0.27, 0.41), thinner lens (β: -0.11; -0.85; 95% CI: -1.02, -0.69) and male sex (β: 0.15; B: 0.50; 95% CI: 0.42, 0.57). In univariate analysis, decrease in refractive error with older age was more significant (β: -0.38 vs. β: -0.25) and steeper (B: -0.22 (95% CI: -0.24, -0.20) vs. B: -0.13 (95% CI: -0.15, -0.11)) in girls than boys, particularly for an age of 11+ years. Axial length increased with older age (steeper for age <11  years) (B: 0.22 (95% CI: 0.18, 0.25) vs. 0.07 (95% CI: 0.05, 0.09)). In multivariable analysis, axial length increased with lower refractive error (β: -0.77; B: -0.42; 95% CI: -0.43, -0.40) and lower corneal refractive power (β: -0.54; B: -0.39; 95% CI: -0.41, -0.38), in addition to older age (β: 0.04; B: 0.02; 95% CI: 0.01, 0.03), male sex (β: 0.13; B: 0.23; 95% CI: 0.21, 0.32), higher cylindrical refractive error (β: 0.05; B: 0.09; 95% CI: 0.05, 0.14) and thinner lens (β: -0.14; B: -0.62; 95% CI: -0.72, -0.51). The axial length/corneal curvature (AL/CR) ratio increased until the age of 14 years (β: 0.34; B: 0.017; 95% CI: 0.016, 0.019; p < 0001), and then became independent of age. The AL/CR ratio increased (r2  = 0.78) mostly with higher corneal refractive power (β: 0.25; B: 0.02; 95% CI: 0.02, 0.02; p < 0.001), lower refractive error (β: -0.75; B: -0.05; 95% CI: -0.05, -0.05; p < 0.001), thinner lens thickness (β: -01.6; B: -0.09; 95% CI: -0.10, -0.08; p < 0.001) and older age (β: 0.16; B: 0.006; 95% CI: 0.005, 0.007; p < 0.001).

CONCLUSIONS

In this multiethnic group of school children in Russia, the age-related increase in myopic refractive error was more significant and steeper in girls, particularly for the age group of 11+ years. Determinants of higher myopic refractive error were longer axial length, higher corneal refractive power, lower cylindrical refractive error, thicker lens and female sex.

Prevalence and Associations of Keratoconus Among Children, Adults, and Elderly in the Population-Based Ural Eye Studies

PURPOSE

To estimate prevalence and associations of keratoconus in populations in Russia with an age from childhood to seniority.

METHODS

The study population consisted of the cohorts of 3 population-based studies performed in urban and rural areas within the same geographical region in Bashkortostan/Russia: the Ural Children Eye Study (UCES; age = 6-18 y; n = 4890), the Ural Eye and Medical Study (UEMS; age = >40 y; n = 5314), and the Ural Very Old Study (UVOS; age = >85 y; n = 651). Based on Scheimflug imaging, keratoconus was defined by a keratometric reading of ≥48 diopters (D) in any eye.

RESULTS

The mean maximal and minimal corneal refractive power increased from the UCES (43.58 ± 1.50 D and 42.70 ± 1.42 D, respectively) to the UEMS (44.26 ± 1.70 D and 43.61 ± 1.76 D, respectively) and to the UVOS (45.1 ± 1.72 D and 43.98 ± 1.68 D, respectively). Correspondingly, keratoconus prevalence increased from the UCES (42/4890; 0.086%; 95% CI = 0.060, 0.112) to the UEMS (112/5314; 2.11%; 95% CI = 1.72, 2.49) and to the UVOS (42/651; 6.45%; 95% CI = 4.56, 8.34). In the UCES, higher keratoconus prevalence was associated (multivariable analysis) with higher birth order [odds ratio (OR) = 2.34; 95% CI = 1.32, 4.15; P = 0.004], lower birth weight (OR = 0.99; 95% CI = 0.99, 0.99; P < 0.001), and shorter axial length (OR = 0.15; 95% CI = 0.08, 0.30; P < 0.001). In the UEMS, keratoconus prevalence correlated with shorter axial length (OR = 0.15; 95% CI = 0.10, 0.23; P < 0.001), larger corneal volume (OR = 1.17; 95% CI = 1.09, 1.25; P = 0.001), thicker lens (OR = 2.27; 95% CI = 1.06, 5.28; P = 0.04), cortical cataract degree (OR = 1.02; 95% CI = 1.01, 1.04; P = 0.01), and higher stage of age-related macular degeneration (OR = 1.65; 95% CI = 1.09, 2.51; P = 0.02). In the UVOS, keratoconus prevalence correlated with lower educational level (OR = 0.84; 95% CI = 0.71, 0.99; P = 0.04) and lower dynamometric handgrip force (OR = 0.92; 95% CI = 0.88, 0.97; P = 0.003).

CONCLUSIONS

In this study on multiethnic groups from Russia, keratoconus prevalence increased from the pediatric group (0.09%) to the adult group (2.11%) and seniority group (6.45%), correlated mostly with biometric ocular parameters and was in all age groups statistically independent of most systemic parameters.