_{Article first published: August 2022, last update: August 2024}

The word myopia is on everyone's lips worldwide. As a visual impairment on the rise, the topic undoubtedly has the power to set the agenda in optometry and ophthalmology. But how critical is the current situation of myopization in particular in school children and teenagers really? In this article, you will learn more about the topic of myopia, progressive myopia, myopia management, current research at ZEISS and the measures ZEISS – as an ophthalmic lens manufacturer – is taking to chart and improve the situation in various regions of the world.

• Myopia is a serious issue worldwide and an acceleratingly important one – especially for people with pathological myopia.
• However, the occurrence of myopia and progressive myopia is subject to regional variations.
• Special eyeglass lenses and contact lenses can make an important contribution to manage the myopia progression.
• Increased time outdoors during childhood, as well as a reduction in near work, should be recommended as preventive measures.
• ZEISS – and especially the ZEISS Vision Science Lab – is involved in several studies of myopia and myopia control solutions together with various external research partners worldwide.
  
  

Basically, myopia (nearsightedness) is a form of visual impairment in which light rays entering the eye are focused in front of the retina. The image produced on the retina is blurred when the uncorrected eye looks into the distance and accommodation is relaxed. This optical defect of the eyes is usually caused by the eyeballs being too long. Usually, myopia first occurs in school-age children and does not necessarily lead to high myopia.

• High myopia starts at -5 diopters – depending on the definition.
• Progressive myopia is characterized by the fact that it gets worse over the years. The length of the eye can continue growing for years. This could, for example, lead to values of -12 diopters. In addition to the health problems that this can cause, it also has a very negative effect on daily life. The furthest point that a person in this case can still see in sharp focus is only eight centimeters from the eye. Normal everyday life without visual aids is then no longer possible.
• Pathologic myopia is characterized by pathological manifestations such as complication in the fundus (for example retinal detachment – see below). Pathologic near sightedness occurs more likely - but not inevitably - in eyes with high myopia.¹
  

Among other factors, myopia can be inherited. For example, if one or both parents are nearsighted there is an increased risk that the child will also become nearsighted. Another factor is the lifestyle, which plays an important role. It is known, for example, that excessive near work, such as intense activity with smartphones or books, has adverse effects.² What is more, children who spend more time outdoors have a lower risk of becoming myopic^.3 It is particularly striking, for instance, that especially in urban Asian regions, the myopia rate is higher than in rural areas.⁴ In other words, regions where everyday life tends to take place indoors. A 2020 study⁵ showed that the Covid 19 pandemic lockdowns amplified this effect - especially among young (six to eight year old) children in China.

More and more people are expected to be myopic in the future. Estimates suggest that half of the world's population could be myopic by 2050 – including approximately ten percent with pathological myopia.^{6 7} The hotspots of myopia are currently in East and Southeast Asia. Among Chinese students younger than 20 years the myopia rate is more than 80%, reaching 90% in urban areas.⁸

Although myopia is currently predominant in Asia, a significant increase can also be identified in other countries and regions. However, the global distribution of myopia is still uneven. While the prevalence in the USA has almost doubled to 42 percent within three decades⁹, the situation in Europe is different again. A myopia prevalence in Central Europe of about 35 percent can be identified from various studies.¹⁰ A study of a German urban cohort of 1,200 children between the ages of two and 19 showed a myopia prevalence of about 18 percent.¹¹ This prevalence is thus much lower than in urban Asian regions.¹² Further investigations as part of the LIFE Child study at the University of Leipzig (see below) should provide further insights into the development of myopia in Caucasian children in the future.

Nevertheless, nearsightedness is a global problem – and if it becomes pathological, it is of course problematic for every single person affected. In such cases the worldwide increase is particularly worrying because – in addition to the reduction of natural vision from early childhood – the risk of later serious eye diseases also increases considerably. In particular, an extreme elongation of the eyeball poses the risk of retinal detachment, macular degeneration or the development of cataract¹³ or glaucoma¹⁴. And it is also problematic from an economic point of view¹⁵ – because good and healthy vision is essential for coping with everyday life and work.

When considering the management of myopia or progressive myopia, it must always be noted that regular stays outdoors have a positive effect on eye development, as does a reduction in near work. Furthermore, single vision eyeglass lenses and contact lenses are important visual aids that can correct the refractive error of the myopic eye. Unfortunately, they are not able to manage the myopia progression. So special solutions are needed. And in fact, today there are several approaches to control or manage the myopia progression:¹⁶

• Eyeglass lenses with special lens designs: they are the most common method because – as a non-invasive method – they do not have the risks and side effects of other solutions. Furthermore, they have the advantage of combining two aspects: the correction of the refractive error while at the same time controlling the progression.
• Soft, multifocal contact lenses: particular designs, so-called ‘center-distance’ lenses, provide a clear image on the fovea centralis (point of sharpest vision), but not in the periphery of the retina. They also have the advantage to combine the correction and control of myopia progression.
• Orthokeratology: The patient wears form-stable contact lenses at night to change the curvature of the cornea, so the wearer can see well without glasses during the day. These lenses have been shown to reduce the progression of myopia.
• Pharmaceutical methods such as atropine eye drops have also been shown to be effective.
  

ZEISS has been working and conducting research for many years with various partners from academia and experts from myopia research so that it is able to offer suitable, needs-based lens solutions. On the Asian market, ZEISS already launched a first myopia management lens "ZEISS MyoVision" more than ten years ago.

From April 2023, ZEISS solutions for the management of progressive myopia will also be available in Europe. The new ZEISS MyoCare lenses will become an essential building block in the management of progressive myopia. In ongoing multi-center trials across Asia and Europe, lenses from the ZEISS MyoCare portfolio are seen to significantly slow progression of myopia as compared to single vision lenses.

The ZEISS Vision Science Lab – located as a research laboratory at the Eye Clinic of the University of Tübingen – is cooperating with various institutes for myopia research, such as the Wenzhou Medical University already mentioned, TU Dublin, the University of Murcia and QUT Brisbane.

To date, there are few cross-sectional studies of myopia in Europe or with Caucasian children. One of these studies is the LIFE Child study of the University of Leipzig. Since 2011, the study examines around 4,500 adolescents and children as well as more than 1,000 pregnant women regarding healthy child development with a special focus on diseases of civilization such as allergies, obesity or depression – and also myopia. For this purpose, among other things, refraction, visual acuity and axial length of the eye are recorded in the long-term panel. The eye health cohort consists of 1,965 children aged three to 16 years.
ZEISS has partnered with the University of Leipzig in this study since 2014 and expects to gain various insights into the development of myopia in Caucasian children. At the present time it has already been possible to develop a percentile curve representation¹⁷ for the refraction and axial length of the child's eye from data taken from the LIFE Child study in collaboration with the ZEISS Vision Science Lab – the first of its kind for Central Europe.¹⁸ The development of an eye can thus be better evaluated in the corresponding age and sex cohort, and statistical predictions can be made more readily. What is striking is that if the Chinese and German percentile curves are superimposed on each other, parts of the curves are far apart. For example, the 50th percentile for eye length¹⁹ for 17-year-olds in Europe is 23 mm, while in Asia it is already 24 mm²⁰. With a rough estimate of 2 diopters per millimeter of eye growth in children, this is a serious difference.

So even if the treatment modalities of myopia progression are similar worldwide, there are regional differences that must be considered: regarding the prevalence, the patients, and the lifestyle. This means myopia management, beginning from diagnosis to intervention, must be adjusted in the various regions of the world.