May 3, 2021 By Dean Psarakis, B. Optom, Senior Research Optometrist, Brien Holden Vision Institute It has been well documented that the prevalence of myopia is high in East Asia, and there is also evidence of increasing rates of myopia elsewhere in the world. As a result, research has focused on interventions to minimize myopic progression in children. Such methods have included the under-correction of myopia, ophthalmic lenses of various forms such as spectacles, soft and hard contact lenses of various designs, and pharmaceutical agents such as atropine.   One of the more successful methods of myopia control has been orthokeratology, with evidence indicating 32% to 55% slower progression with OrthoK lenses compared to single vision spectacles. However, only spherical OrthoK lens designs were commonly employed, and hence efficacy data was limited to eyes with low amounts of astigmatism (≤-1.50D). Chen et al. 2013 recognized the need to examine the myopia control efficacy of reverse geometry toric OrthoK lenses in moderate to high amounts of astigmatism.  Since there was no prior evidence on the safety and efficacy of toric OrthoK lenses, the investigators conducted a non-randomized trial whereby parents elected to have their children assigned to either the conventional (spectacles) or new (toric OrthoK) treatment group. The aim was to determine the efficacy of toric OrthoK lenses for myopia control in astigmatic children, with the primary endpoint being axial length elongation over 24 months. A total of 43 and 37 participants were enrolled into the OrthoK and the spectacle groups, respectively, of which 35 and 23 completed 24 months respectively. Myopic participants were aged between 6 and 12 with refractive astigmatism of between 1.25D and 3.50D.  Results indicated significantly slower axial elongation in the OrthoK group at every six-month interval than the control group (0.33mm less elongation over 24 months equated to a 52% reduction in myopia progression). In terms of myopic progression, the odds of becoming a fast progressor (>0.36mm axial elongation) were 14.9 times greater in the single vision group compared to the OrthoK group. The toric OrthoK lens successfully corrected the refractive error, including astigmatism. Myopia reduced from 2.46D at baseline to 0.18D at the six-month visit, with no subsequent change thereafter. Similarly, the average refractive astigmatism changed from -1.86D to -0.37D in the first six months with no subsequent change. In comparison, in the control group, the average amount of myopia increased steadily at every interval from … Continue reading Myopia Control Using Toric Orthokeratology