Heros are people who are admired for their courage, outstanding achievements, or noble qualities. Let’s imagine orthokeratology (OK) as a hero in myopia control—evolving from an icon over a decade ago to now occupying a “quiet achiever” space in the increasingly rich landscape of myopia control options.

The Icon

OK was the first optical intervention to show significant promise for myopia control (Cho et al, 2005). Its absolute effect of 0.25mm less axial growth over two years in OK wearers, representing around a 50% control effect, greatly exceeded prior efforts with progressive addition spectacle lenses (Edwards et al, 2002; Gwiazda et al, 2003). Fulk et al (2000) studied ocular growth with bifocal spectacle lenses and similarly found no significant alteration. Walline et al revealed in 2004 that standard alignment-fit GPs don’t control myopia and showed the same in 2008 for single-vision soft contact lenses (SCLs) versus spectacles.

The explosion of myopia control research and options since Cho et al’s landmark 2005 paper is staggering. It was only a year later that the first indication of bifocal SCL myopia control emerged (Aller and Wildsoet, 2006). Walline et al reinforced OK’s icon position in 2009 with another historically controlled study, showing a similar two-year effect of around 50%. At that time, only 1% atropine had been investigated for myopia control (Chua et al, 2006), but a significant rebound effect was reported by Tong et al (2009).

The Quiet Achiever

In 2012, Santodomingo-Rubido et al published the first prospective, randomized, controlled trial on OK for myopia control, just a few months before the second by Cho and Cheung (2012). Both two-year studies showed similar results to the prior publications that had historic control groups, with 0.22mm (32%) and 0.27mm (43%) absolute reduction in axial elongation. Later studies confirmed these, and two meta-analyses showed an effect across seven studies of 0.26mm (Si et al, 2015) and of 0.27mm or 45% (Sun et al, 2015) over two years.

Since then, a cascade of first-time studies on novel-design (Sankaridurg et al, 2011) and dual-focus concentric (Anstice and Phillips, 2011) SCLs, lower-concentration atropine (Chia et al, 2012), center-distance multifocal SCLs (Walline et al, 2013), bifocal and prismatic bifocal spectacle lenses (Cheng et al, 2014), more multifocal SCLs (Cooper et al, 2018; Sankaridurg et al, 2019; Pauné et al, 2015), 0.01% to 0.05% atropine (Yam et al, 2019), and the first myopia-controlling spectacle lens to work as well as OK (Lam et al, 2020) have published. Randomized, controlled trials on today’s dual-focus and multifocal SCL options were only published in 2019 (Sankaridurg et al; Chamberlain et al) and 2020 (Walline et al). Current studies underway could alter the landscape again in the coming years.

The foundational understanding of OK continues to grow. Charm and Cho (2013) confirmed OK’s ability to partially correct high myopia, and it is the only optical intervention to show efficacy for higher amounts of astigmatism with myopia (Chen et al, 2013). As a single intervention, OK has continued to amass arguably the largest evidence base for myopia control efficacy.

The Bottom Line

OK will likely never be the hero of all myopia control due to the required specialty equipment and fitting expertise. OK doesn’t enjoy the same safety profile as daily disposable SCLs, although its safety is similar to that of reusable SCLs (Bullimore, 2017; Stapleton et al, 2008; Bullimore et al, 2013).

Contact lens options will continue to play a key role in myopia control. Hence, as research evidence and clinical interest continue to grow, OK is set to remain the specialty lens hero of myopia control. CLS

For references, please visit www.clspectrum.com/references and click on document #305.