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

Abstract

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.

Keywords: children and adolescents; cycloplegic refraction; myopia; myopic progression; public health; refractive error.

Figure 1

Flow diagram describing data selection.

Figure 2

(A) Average 1st year progression rates (D/y) and total number of individuals as a function of the year of first visit through the period from 2008 till 2022. The left y-axis is related to the number of individuals (red line), and the right y-axis is related to progression rates (blue line). (B) Average 3-year progression rates (D/y) and total number of individuals as a function of the age of the first visit. The left y-axis is related to the number of individuals (red line), and the right y-axis is related to progression rates (blue line).

Figure 3

Heatmap of average 1st year low myopia progression (in diopters) according to age and year of the first visit. Darker colors indicate more rapid progression rates (D/y).

Figure 4

(A) Average progression of low myopia (in diopters) as a function of time (in years) stratified by baseline age groups. Bars display 95% CIs. (B) Average progression of low myopia (in diopters) as a function of time (in years) stratified by baseline spherical equivalent (SE). Bars display 95% CIs. (C) Average progression of myopia (in diopters) as a function of time (in years) stratified by gender. Bars display 95% CIs.

Figure 5

Heatmap of low myopia individuals odds ratio to progress faster or equal −0.5 D/y in the period between 11 and 24 months after the first visit, stratified by age and baseline SE. Darker tones indicate higher OR values. The p-value for the model is <0.001.

Figure 6

(A) Kaplan–Meier failure curves for the event ‘develops high myopia’ stratified by spherical equivalent at baseline. (B) Kaplan–Meier failure curves for the event ‘develops high myopia’ stratified by baseline age groups.