Normative data for macular and retinal nerve fibre layer thickness in healthy German children and adolescents using optical coherence tomography

PURPOSE

To establish normative data for macular thickness, macular volume and peripapillary retinal nerve fibre layer (RNFL) thickness using Spectralis® spectral-domain optical coherence tomography (SD-OCT) in healthy German children and adolescents and investigate influencing factors.

METHODS

The cross-sectional study included the right eye of 695 children with at least one complete retinal OCT scan. As part of the LIFE Child study, the children underwent an ophthalmological examination including axial length (AL), spherical equivalent (SE) and OCT measurements. Various questionnaires were answered by the children or their parents to identify media use or outdoor time. Multiple linear regression models were used to investigate the potential influencing factors.

RESULTS

A total of 342 boys and 353 girls with an average age (SD) of 12.91 (3.29) years participated. The mean AL (SD) was 23.20 (0.86) mm. The mean macular thickness (SD) was 320.53 (12.29) μm and the mean RNFL thickness (SD) was 102.88 (8.79) μm. Statistical analysis revealed a significant correlation between average macular thickness and age (p < 0.001, β = 0.77) as well as AL (p < 0.001, β = -4.06). In addition, boys had thicker maculae (p < 0.001, β = 5.36). The RNFL thickness showed no significant correlation with children's age (p > 0.05), but with AL (p = 0.002, β = -2.15), birth weight (p = 0.02, β = 0.003) and a gender-specific effect of the body mass index standard deviation score for male participants (p = 0.02, β = 1.93).

CONCLUSION

This study provides normative data and correlations between macular and RNFL thickness in healthy German children. Especially age, gender and AL must be taken into account when evaluating quantitative OCT measurements to classify them as normal.

Longitudinal analysis of axial length growth in a German cohort of healthy children and adolescents

PURPOSE

To generate continuous growth curves for axial length (AL) in German children. We hypothesise that percentile curves of AL can be used as a predictive measure of myopia.

METHODS

In this longitudinal and cross-sectional LIFE Child Study, children's non-cycloplegic refraction data was collected using the Zeiss i.Profiler plus while AL was measured using the Haag-Streit Lenstar. Reference growth curves were estimated as a continuous non-parametric function of age.

RESULTS

Data from 4511 visits of 1965 participants (1021 boys and 944 girls) between 3 and 18 years of age were analysed. For all ages and percentiles, the estimated AL was higher in boys than girls. AL differences between boys and girls were most pronounced in the 98^th percentile at 3 years of age, being 0.93 mm longer eyes in boys. This difference decreased to 0.21 mm at 18 years of age. While the lower percentiles of AL reach their final value around age 13, the 50^th percentile was still increasing by 0.05 mm per year until the end of the observation period. While, in general, children with longer eyes are more likely to develop myopia, this relationship is weaker between the ages of 5 and 8.

CONCLUSION

The LIFE Child Study data provides European AL data. In both Germany and China, AL has comparable growth rates when the baseline ALs are compared as percentiles. Thus, percentile curves of AL can be used as a predictive measure for the likelihood of developing as well as the progression of myopia.

Impaired visual acuity caused by uncorrected refractive errors and amblyopia in a German paediatric cohort

PURPOSE

This study describes the prevalence of visual impairment caused by uncorrected distance refractive error and the spectacle coverage in a large cohort of German children and adolescents. Furthermore, we determined the prevalence of amblyopia and amblyopia treatment.

METHODS

Optometrists carried out visual acuity (VA) testing, non-cycloplegic autorefraction, VA retesting with the refractive correction obtained by autorefraction, and if necessary subjective refraction and cover-test in 1,874 subjects (901 girls/973 boys), aged 3 to 16 years. Additionally, a questionnaire on the history of previous eye care was completed.

RESULTS

Distance visual impairment (VI) with VA worse than 6/18 Snellen in the better eye was present in 0.5% (95% confidence interval [95% CI]: 0.2% to 0.9%) of children. Logistic regression showed a significant positive association between VI and older age (OR = 1.21, P = 0.03). Gender differences were not found (P = 0.77). The spectacle coverage of all participants was 74.8% (95% CI: 65.2% to 82.8%). Amblyopia was found in 29 participants (1.5%; 95% CI: 1.0% to 2.2%) with no age or sex differences. The causes of unilateral amblyopia (27 cases, 93.1%) were anisometropia in 55.6% of children, strabismus in 25.9% and the combination of these factors in 18.5%. All children with bilateral amblyopia (2 cases, 6.9%) showed bilateral high ametropia. We observed 15 children with current amblyopia, who had been treated with occlusion therapy in the past (62.2%; 95% CI: 42.7% to 83.6%).

CONCLUSIONS

The prevalence of impaired VA caused by uncorrected refractive error and amblyopia is comparable with previous studies conducted in urban areas worldwide. Adding the measurement of refractive error to existing medical check-ups, possibly using autorefraction, would be desirable.

Reference curves for refraction in a German cohort of healthy children and adolescents

PURPOSE

Percentile curves of refractive development for German children were generated. We hypothesize that refraction in children in central Europe might differ from data in central Asia.

METHODS

Non-cycloplegic refraction was measured using the ZEISS i.Profiler plus (Carl Zeiss Vision GmbH, Germany) in 1999 children, of which were 1046 male and 953 female, aged 3 to 18 years. Reference curves were calculated with the R-package GAMLSS as continuous function of age.

RESULTS

There were only little differences for all centiles between the genders at 3 years and a general trend towards more myopia with increasing age. For the 97th centile and the 3rd centile, girls showed higher myopia/ less hyperopia than boys. Between the age of 3 and 18, the median refraction became -0.68 D and -0.74 D more myopic for boys and girls, respectively. At the same time, the 97th centile for boys changed +0.29 D towards hyperopia and in girls -0.52 D towards myopia. A general myopic trend was seen in the 3rd centile, which was -2.46 D for boys and -2.98 D for girls. For both genders, the median became less than zero at the age of 10 years but did not become myopic (less than -0.5 D) up to the age of 18.

CONCLUSION

Our analysis presents the first reference curve for refraction in central Europe. In comparison to data from China and Korea, there is only little difference at the age of 5 years in all centiles which then increases continuously. For all ethnicities, a trend towards myopia with increasing age could be observed, but myopia progression is much higher in China and Korea than in Germany. The most marked differences can be seen in the lower centiles. Further investigations should clarify whether commencement of preschool activities with prolonged near-work initiates the divergence in refractive development.