For a Good Start – Good Vision in Childhood

The development of the human eye begins before birth and continues well after – into school age. A regular development of the refractive power of the eye in comparison to its axial length over time is called emmetropization.

The most common form of ametropia in children – in other words defective vision – is so-called axial ametropia. Its cause, as the name suggests, lies in the axial length of the eyeball. If the eye is too short compared to the refractive power of its refractive media (cornea, lens, aqueous humor and vitreous body), farsightedness (hyperopia) develops; if the eye is comparatively too long, nearsightedness (myopia – Fig. 1) develops. Ideally, the growth of the eyeball over time ensures that the eye becomes right-sighted (emmetropic). The refractive power of the refractive media and the length of the eye are then exactly matched. According to current knowledge, this growth process is controlled by the retina. As a projection surface it adapts to the shape of the eye and thus enables the formation of good vision.²

An initial comprehensive ophthalmic and orthoptic examination for children is recommended after the second year of life, as vision develops particularly rapidly in the first two years of life. In this way, visual impairments can be detected early and mitigated with the right treatment.³

With regard to refractive errors in children and adolescents, myopia is currently receiving special attention. With a predicted prevalence of 50 percent by 2050 for the world's population, myopia is a global challenge, although there are significant regional differences.⁴ Also striking is the increase in progressive and high myopia, which can have serious consequences for eye health.

Various studies investigate the role of vision in relation to school performance.⁶ The results indicate that there is a relationship between performance and visual acuity and refractive errors in children.⁷ The ability to take in visual information affects learning potential. For example, visual complaints can delay the completion of schoolwork and homework, which in turn can lead to distraction and inattention. The increased time required to complete schoolwork, in turn, provides less time for practice and learning. If an associative relationship is developed between eye discomfort and learning activity, interest and motivation can be permanently disrupted or even lead to avoidance. Blurred or distorted perception of text can affect the speed and efficiency of word processing, reading speed, and reading comprehension.⁸

"School age is an important period when we talk about the formation of clear, pleasant vision and the associated development. Increasing digitalization, also in learning, further increases the importance of visual content and shows how important the absorption of information via the eye is. The right precautions for and care of children are essential here," says Patrick Michel, ZEISS expert for children's lenses.

The switch between the digital and physical worlds is increasingly determining the viewing needs of children and adolescents. Globally, digital devices such as laptops or smartphones have become an important part of daily life across all age groups. Children and adolescents naturally play, learn and communicate using technologies such as augmented reality. The combination of the physical and digital worlds is thus becoming more immersive and relevant.

In a 2020 survey, parents were asked about their children (age <12) and their use of digital devices. The result: 60 percent of parents said their children were already using a smartphone before the age of five.⁹ Due to the pandemic, the use of digital media has continued to rise. In 2021, for example, daily use among 14- to 69-year-olds in Germany was 10.5 hours per day. Increasing usage times are particularly noticeable among ever younger children.¹⁰

In 2019, the ZEISS Dynamic Gaze Study¹¹ already provided important findings for the holistic understanding of today's visual behavior and showed that visual requirements based on visual activity and head movement differ depending on age. Especially when correcting refractive errors in childhood and adolescence, it must be taken into account that major anatomical and physiological changes take place in this phase of life, which also have an influence on visual behavior and, if necessary, on the correct spectacle prescription (Changes in facial anatomy in childhood and adolescence – Fig. 2).

"When using smartphones, children's viewing distances are much shorter than those of adults. School beginners still hold digital devices very close to their faces – at a distance of about 20 centimeters, while teenagers hold them at a distance of 30 centimeters. This simply has to do with the length of their arms," explains Michel.

When prescribing eyeglasses, it is important to note that the anatomical changes of the face directly affect the wearing parameters and thus the optical performance. This must be taken into account during lens calculation and fitting.

To support healthy eye development, the International Myopia Institute recommends for all children: spending more time outdoors and limiting screen and smartphone time to two hours per day. That's because playing or exercising outside is essential to children's healthy growth and development. Studies show that spending time outdoors provides various benefits for overall well-being, physical and mental health, and eye and vision development. The prerequisite for this is adequate protection against UV radiation.^13,14 This is because, while natural sunlight is the source of visible light, it is also the most intense source of UV radiation and blue light. The need for UV protection is generally recommended due to the harmful effects of UV radiation on our eyes and skin.^15,16 Blue-violet light, as part of the blue light spectrum, is considered potentially damaging to cellular structures due to its higher photon energy.^17,18 However, the intensity of artificial blue light emitted by screens, for example, is so low that this light is not harmful. Nevertheless, it can lead to subjectively perceived digital visual stress and tired eyes.¹⁹

There is currently no scientific evidence that filtering blue light and UV radiation has negative consequences for children. If recommended by an eyecare professional, UV protection as well as blue light protection is suitable for all age groups.

To address the visual needs of children and young people, ZEISS offers two lens types: ZEISS SmartLife Young single vision lenses optimized for the visual needs of six- to 19-year-olds and ZEISS MyoCare lenses as part of ZEISS Myopia Management for progressive myopia.

^{Sources / remarks:}

^{1. Cf. Deutsche Bundeszentrale für gesundheitliche Aufklärung (Federal Centre for Health Education): Die Entwicklung des Sehvermögens | kindergesundheit-info.de accessed June 2023.}

^{2. Cf. Troilo D, Smith EL 3rd, Nickla DL, Ashby R, Tkatchenko AV, Ostrin LA, Gawne TJ, Pardue MT, Summers JA, Kee CS, Schroedl F, Wahl S, Jones L. IMI – Report on Experimental Models of Emmetropization and Myopia. Invest Ophthalmol Vis Sci. 2019 Feb 28;60(3):M31-M88. doi: 10.1167/iovs.18-25967. PMID: 30817827; PMCID: PMC6738517. Available online at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6738517/ accessed June 2023.}

^{3. Cf. BVA / DOG: Guideline No. 2 Basic ophthalmological diagnostics in children in the first two years of life. Available online at: Guideline No. 2 Basic ophthalmologic diagnosis in children in the first two years of life.doc (dog.org), accessed June 2023.}

^{4. While up to 90 percent of urban youth are affected in Southeast Asia, the case numbers in Europe are significantly lower. According to current evidence, the causes, especially for progressive myopia, also vary to some extent from region to region.}

^{5. Cf. Aleman AC, Wan M, Schaeffel F. Reading and Myopia: Contrast Polarity Matters. Sci Rep 8, 10840 (2018). https://doi.org/10.1038/s41598-018-28904-x, accessed May 2023.}

^{6. Cf. Borsting E, Rouse MW. Detecting learning-related visual problems in the primary care setting. J Am Optom Assoc 1994; 65: 642-650.
Krumholtz I. Results from a pediatric vision screening and ist ability to predict academic performance. Optometry 2000; 71: 426-430.}

^{7. Hopkins S, Narayanasamy S, Vincent SJ, Sampson GP, Wood JM. Do reduced visual acuity and refractive error affect classroom performance? Clin Exp Optom. 2020 May;103(3):278-289. doi: 10.1111/cxo.12953. Epub 2019 Aug 22. PMID: 31441091. https://onlinelibrary.wiley.com/doi/pdf/10.1111/cxo.12953, accessed May 2023.}

^{8. American Academy of Optometry. Optometric Clinical Practice Guideline: Care of Patient with Learning Related Vision Problems. 2008. St. Louis, MO: American Optometric Association. https://www.aoa.org/AOA/Documents/PracticeManagement/ClinicalGuidelines/Consensus-basedguidelines/CareofPatientwithLearningRelatedVisionProblems.pdf, accessed May 2023.}

^{9. Auxier B. et al. Children’s engagement with digital devices, screen time. Pew Research Center. 2020.}

^{10. Degle, S: Steigender digitaler Medienkonsum von Kindern – Gefahren und gesundheitliche Folgen, aber auch Lösungsvorschläge und Perspektiven, Available online at: https://www.eah-jena.de/hochschule/nachricht/steigender-digitaler-medienkonsum-von-kindern-gefahren-und-gesundheitliche-folgen-aber-auch-loesungsvorschlaege-und-perspektiven, accessed June 2023.}

^{11. ZEISS Dynamic Gaze Study, ZEISS Vision Science Lab Tübingen, 2019.}

^{12. Koudelová J et al.. Simulation of facial growth based on longitudinal data: Age progression and age regression between 7 and 17 years of age using 3D surface data. 2019.}

^{13. Mead MN. Benefits of sunlight: a bright spot for human health. Environ Health Perspect. April 2008;116(4):A160-7. doi: 10.1289/ehp.116-a160.}

^{14. Fernandez DC. et al. Light Affects Mood and Learning through Distinct Retina-Brain Pathways. Cell. Sep. 2018;175(1):71-84.e18. doi: 10.1016/j.cell.2018.08.004.} 

^{15. According to the World Health Organization (WHO), about 20 percent of all cataract diseases are caused or exacerbated by UV radiation. Global data on visual impairment in the year 2002. Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, Pokharel GP, Mariotti SP Bull. Weltgesundheitsorganisation. Nov 2004; 82(11):844-51.}

^{16. Cook BE Jr, Bartley GB. Treatment options and future prospects for the management of eyelid malignancies: an evidence-based update. Ophthalmology Nov. 2001; 108(11):2088-98: 5 to 10 percent of all skin cancers occur on the eyelids specifically.}

^{17. Taylor HR, West S, Muñoz B, Rosenthal FS, Bressler SB, Bressler NM. The long-term effects of visible light on the eye. Arch Ophthalmol. Jan., 1992;110(1):99-104. doi: 10.1001/archopht.1992.01080130101035.}

^{18. Tomany SC, Cruickshanks KJ, Klein R, Klein BE, Knudtson MD. Sunlight and the 10-year incidence of age-related maculopathy: the Beaver Dam Eye Study. Arch Ophthalmol. May, 2004;122(5):750-7. doi: 10.1001/archopht.122.5.750.}  

^{19. Rosenfield M. Computer vision syndrome: a review of ocular causes and potential treatments. Ophthalmic Physiol Opt. Sep. 2011;31(5):502-15. doi: 10.1111/j.1475-1313.2011.00834.x}