Myopia control in the 21st century: A review of optical methods (2000–2019)

Background: Without appropriate interventions, simple or low myopia can progressively get worse and lead to high myopia. Patients with high myopia are at a greater risk of developing retinal detachment, myopic macular degeneration, glaucoma and eventual blindness in some cases, and hence the reason for the global call for myopia control. Consequently, myopia in the 21st century is not only treated as a refractive error but an ocular disorder with potential negative consequences. Myopia control strategies include optical, pharmacological and behavioural methods. In this report, the effectiveness of optical methods of myopia control was reviewed. Aim: The aim of the review is to evaluate and summarise existing knowledge on myopia control and provide recommendations to guide future studies. Method: The review was conducted using online search engines including PubMed and Google Scholar. Articles published between 2000 and 2019 were included. Results: For the optical methods of myopia control, under-correction has been found to be largely ineffective. However, a recent study shows that myopic children without correction had slower myopia progression (−0.75 D) than fully corrected children (−1.04 D) indicating a 28% reduction. Evidence from various studies indicates that bifocals and progressive addition lenses are not as effective as soft dual focus contact lenses or extended depth of focus contact lenses. Clinical trials indicate that single vision rigid gas permeable lenses did not slow myopic progression. Peripheral defocus lenses and orthokeratology were found to be approximately 50% effective across studies reviewed. Conclusion: Peripheral defocus lenses and multifocal contact lens designs offer the most effective myopia control. Orthokeratology is equally effective but future designs should consider ways of minimising risks of complications with lens wear. More studies would be needed to better understand how under-corrected myopic eyes tend to progress faster, whereas myopic eyes without correction tend to progress slower. A holistic approach and combination of methods may offer the best form of myopia control in the 21st century considering the increase in near work activities and use of digital devices among the most vulnerable groups.