Dr Paul Gifford consults with the contact lens industry on development of contact lens designs and their implementation into clinical practice. He is a partner in private practice conducting clinical research on use of contact lenses and orthokeratology to control progression of myopia, and holds an Adjunct Senior Lecturer position at the School of Optometry and Vision Science, University of New South Wales, Sydney.
Both orthokeratology (OK)1,2 and atropine3 have been shown to slow the progression of myopia. This naturally leads to the question of what may happen if both treatments were to be combined. Pauline Cho’s Hong Kong Polytechnic based research group have set about answering this very question and presented their initial 6-month results at the Association for Research in Vision and Ophthalmology (ARVO) conference in Vancouver, Canada, 2019.
Prior to this work, the peer-reviewed literature contained just two papers on the subject. Wan et al. published a retrospective analysis across two-years which compared children who had worn only OK against those that had combined atropine with OK wear.4 However this early work has been criticised for a number of aspects relating to study design and data analysis.
Kinoshita et al. measured axial eye length after 3 months of OK lens wear to act as a baseline measure and then randomly assigned half of the cohort to use 0.01% topical atropine once nightly in addition to continuing OK lens wear, with the remaining participants continuing with OK wear only.5 After one year they reported 52% less axial eye elongation across the combined therapy cohort. While promising, their results need to be considered in the light of unbalanced study groups. The OK-only control cohort contained a higher proportion of younger subjects, which may have resulted in a faster natural progression of myopia in this group.
More recent work has been undertaken by Pauline Cho’s group, comparing combined OK and atropine 0.01% against OK alone. Importantly, the study has well-balanced participant grouping, and their early results, presented at ARVO, 2019 indicate slower axial eye elongation in the combined therapy cohort. The authors also reported the combined therapy to be well tolerated. The abstract shared at the conference is outlined below.
Ng LK, Tan Q, Cheng GP, Woo VC, Cho P. Combined atropine with orthokeratology in childhood myopia control (AOK) – A randomized controlled trial. Invest Ophthalmol Vis Sci. 2019;60:3899
Purpose: To present the initial 6-month results of a two-year randomized control trial, comparing the efficacy of combined 0.01% atropine with orthokeratology (AOK) versus orthokeratology alone (OK) for myopia control.
Methods: This is an examiner-masked, randomized control trial carried out in Hong Kong. Chinese children, aged from 6 to 11 years old, with 1.00 to 4.00 D myopia and astigmatism less than 2.50 D were recruited. They were randomly assigned to AOK or OK groups. In the AOK group, single-dose 0.01% preservative-free atropine was given topically to both eyes every night before ortho-k lens wear. The primary outcome measure was the axial length elongation measured using partial coherence interferometry (IOL master 500).
Results: Thirty subjects were included in the AOK group and 35 in the OK group. The average age was 9.1±1.2 years in AOK and 9.1±1.0 in OK. The OK lens first-fit success rate was 97% and 94% respectively. At the 6-month visit, there were 30 subjects in AOK group and 32 subjects in OK group (3 were terminated from the study due to contact lens intolerance). Axial elongation in AOK group was -0.02 ± 0.11 mm (-0.16 – 0.03 mm) and that in OK group was 0.06 ± 0.09 mm (P = 0.0027). Atropine 0.01% ophthalmic solution, when combined with ortho-k lens wear, was well-tolerated in all subjects.
Conclusions: Our initial 6-month result showed that combination of single-dose 0.01% atropine with ortho-k lens wear have an additive effect in slowing axial elongation, when compared with monotherapy of ortho-k alone or 0.01% atropine alone. The combined treatment was well-tolerated.
REFERENCES:
- Si, J.-K. et al. Orthokeratology for myopia control: a meta-analysis. Optom Vis Sci. 2015;92:252–257.
- Sun, Y. et al. Orthokeratology to control myopia progression: A met-analysis. PLoS One. 2015;10:e0124535.
- Yam, J. C. et al. Low-concentration atropine for myopia progression (LAMP) study myopia control. Ophthalmol. 2019;126:113–124.
- Wan, L. et al. The synergistic effects of orthokeratology and atropine in slowing the progression of myopia. J Clin Med. 2018;7:259.
- Kinoshita, N. et al. Additive effects of orthokeratology and atropine 0.01% ophthalmic solution in slowing axial elongation in children with myopia: first year results. Japanese J of Ophthalmol. 2018;62:1–10.
