The latest from the IMI and what it means in practice
In this article:
The International Myopia Institute (IMI) is a global group of scientific experts who have come together to discuss, debate and make available the latest evidence based recommendations in classifications, patient management, and research - in the form of the IMI White Paper Reports. Volume One of the White Papers was published in February 2019, with seven individual reports covering Definitions, Experimental Models, Genetics, Interventions, Clinical Trials, Ethics and Clinical Management Guidelines.
Volume Two was published in April 2021, with six reports on the Impact of Myopia, Risk Factors, Accommodation and Binocular Vision, Pathologic Myopia, Prevention of Myopia and its Progression and the 2021 Yearly Digests, providing updates on the 2019 Report topics. The following is a brief summary of these Volume Two reports, providing links further reading for each: the full open-access research papers, the IMI Clinical Summaries (available in several languages) and the Myopia Profile Science review for each paper.
IMI Report on Impact of Myopia
This report describes the global burden of myopia, on individuals as well as on society in the areas of risk of vision impairment; reduced education outcomes; economic impact due to direct cost and lost productivity and reduced quality of life. Quality of life impacts include social, emotional, global, convenience, symptoms and activity limitation factors.
Unless the current trajectory for the rising prevalence of myopia and high myopia change, the costs and burden will continue to grow. Shifting the trajectory requires a coordinated global effort. An early and appropriate intervention by eye care practitioners mitigates the risks and consequences related to uncorrected vision. More importantly, it can reduce the risk of myopia progressing to higher levels. This has a positive impact on reducing the burden of myopia.
IMI Report on Risk Factors for Myopia
This report details the modifiable and non-modifiable risk factors for myopia which have driven the swift global increase in myopia prevalence. These include:
- Education and near work (modifiable): increased educational pressure and higher academic performance are associated with myopia. The role of digital devices as separate to near work in general is yet to be determined.
- Time outdoors (modifiable, protective): considerable evidence to support delaying myopia onset, but mixed evidence for slowing progression. The mechanism may be bright light stimulation of retinal dopamine. School-based interventions have shown impact, with widespread implementation across schools in Taiwan.
- Birth parameters (non-modifiable): ethnic differences may be moderated by environmental factors; myopic parents contribute both genetics and myopigenic lifestyle factors to their children; and first borns tend to be more myopic.
From a clinical perspective, recommending that children spend two hours per day outside during daylight hours, particularly in the preschool and early primary school years, is a key myopia prevention intervention. Limiting homework and near work time at these ages is also recommended.
IMI Report on Accommodation and Binocular Vision in Myopia Development and Progression
This report explores the link between accommodation, binocular vision and myopia; as well as the mechanisms involved in how accommodation alters the ocular structures in myopia, such as the ciliary body and choroid. Overall, correlations have been found between greater lag of accommodation, elevated convergence and higher AC/A ratios and myopia, but these have not been found to be causative in myopia progression. The role of accommodation in providing a clear retinal image has not been ruled out as a myopia mechanism, but interventions based on accommodation have so far not yielded significant results.
Even though the role of accommodation and binocular vision in myopia development and progression is not fully understood, clinicians should still assess the accommodation and vergence systems in young myopes and those at risk of myopia development, to ensure a clear retinal image.
IMI Report on Pathologic Myopia
This report describes 'pathologic myopia' as separate from 'high myopia', being "Excessive axial elongation associated with myopia that leads to structural changes in the posterior segment of the eye (including posterior staphyloma, myopic maculopathy, and high myopia-associated optic neuropathy) and that can lead to loss of best-corrected visual acuity." This report describes diagnosis using the META-PM classification system using fundus photographs (see Table 2 in the full paper), and includes the addition of new OCT classification, including myopic traction maculopathy (MTM) (see Table 4). It also describes management and new treatments aimed at preserving vision in pathologic myopia.
IMI Report on Prevention of Myopia and its Progression
All parents and children should be advised of increasing time spent outdoors to combat myopia. This article provides a relevant summary of the pharmacological and optical interventions that can be implemented in clinical practice to delay myopia onset, as reducing myopia progression.
- Delaying onset: Increasing time spent outdoors to at least 80 to 120 minutes per day to reduce development of myopia. This advice is in line with other general healthy lifestyle advice for children.
- Slowing myopia progression: atropine 0.01% to 0.05%, where the stronger concentration was most effective; optical treatments including spectacles and contact lenses where some are more effective than others.
Considerations of selecting a treatment include the risk-to-benefit balance for the individual based on their age, health and lifestyle; and availability of treatments. Combining treatments is showing early data - which may act on different mechanisms of myopia - and may become more common in future.
IMI 2021 Yearly Digest
The IMI 2021 Yearly Digest is a culmination of research providing updates on high impact clinical trials, new interventions and updated understanding in myopia management, since Volume One of the IMI reports were published in early 2019. A search of PubMed revealed 1,000 research articles on myopia published in 2019 and 2020, and committees which published full IMI Reports in 2019 provided a short update of advances in their area since. Here are key findings of each.
- Defining and Classifying Myopia: the new definition of premyopia is now being included in studies underway to test myopia interventions; in pathologic myopia, myopic traction maculopathy (MTM) is a new definition specific to optical coherence tomography (OCT).
- Experimental Models of Emmetropization and Myopia: treatments to reduce intraocular pressure, understanding retinal dopamine signalling, gene-environment interactions and the impact of circadian rhythms are showing promise in experimental (animal) models of myopia.
- Genetics of Myopia: a large meta-analysis of refractive error has identified 336 new genetic loci for myopia, regulating factors from ocular structure and development and central nervous system-related genes (eg. retinal signalling), increasing accuracy of potential genetic testing for high myopia risk.
- Interventions for Controlling Myopia Onset and Progression: new publications since 2019 have demonstrated myopia control efficacy of defocus incorporated multisegment spectacles (DIMS), dual-focus and other multifocal contact lenses, atropine 0.025% and 0.05%. and the combination of 0.01% atropine and orthokeratology.
- Clinical Myopia Trials and Instrumentation: with mounting evidence for myopia control efficacy comes the ethical dilemma of continuing with placebo control groups in studies; and discussion of outcome reporting using absolute versus percentage reductions as a measure of efficacy
- Clinical Management Guidelines for Myopia: new papers have outlined the latest guidance for practice; indicated that contact lens prescribing for the risk of childhood contact lens wear is lower than the visual impairment risks of myopia; increase in global contact lens prescribing for childhood myopia; and why each dioptre matters in myopia.
Meet the Authors:
About Kate Gifford
Dr Kate Gifford is a clinical optometrist, researcher, peer educator and professional leader from Brisbane, Australia, and a co-founder of Myopia Profile.
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