One-year results of 0.01% atropine with orthokeratology (AOK) study: a randomised clinical trial

To report the 1-year results of an investigation into whether there is an additive effect between 0.01% atropine and orthokeratology (ortho-k), in a single-masked, two-arm, randomised controlled trial: Combined Atropine with Orthokeratology (AOK) for myopia control study (ClinicalTrials.gov number: NCT02955927).

Chinese children aged between 6 and 11 years with 1.00-4.00 D of myopia, astigmatism <2.50 D, and no more than 1.00 D anisometropia, were randomly assigned either to an AOK group or ortho-k only (OK) group at a 1:1 ratio. Subjects in the AOK group instilled one drop of 0.01% atropine into each eye, 10 min before nightly wear of ortho-k lenses. The primary outcome, axial elongation, was examined at 6-monthly intervals, along with secondary outcomes including best-corrected visual acuity (BCVA), manifest refraction, accommodation, pupil size, and corneal topography.

29 AOK and 30 OK subjects completed the 1-year visit. The overall axial elongation rate was significantly slower in the AOK group than in the OK group (mean (S.D.), 0.07 (0.16) mm vs 0.16 (0.15) mm, respectively; p = 0.03). A significant between-group difference in axial elongation was observed over the first 6-month period only (p < 0.001), but not over the second period (p = 0.818). At the 1-year visit, increases in mean (S.D.) mesopic and photopic pupil sizes in the AOK group were 0.64 (0.48) mm and 0.36 (0.34) mm, respectively, which were significantly higher than 0.10 (0.50) mm and 0.02 (0.28) mm in the OK group (p < 0.001). At the 6-month visit, a significant moderate negative correlation was found between axial elongation and the increase in photopic pupil size (r = -0.42, p = 0.02) in the AOK group.

There is an additive effect between 0.01% atropine and ortho-k over one year, with mean axial elongation in the AOK group 0.09 mm slower than that in the OK group. It appears that the additive effect was only during the first six months; a second-year investigation is warranted to determine whether the effect is sustained over time.