Optical treatment with DIMS was significantly associated with slower myopia progression compared to SVL treatment during the lockdown period.
Henry Ho-lung Chan, PhD
The progression of myopia has been found to be worsening during the COVID-19 pandemic, in comparison to historical numbers and recent studies, particularly for schoolchildren as a result of lockdown-related behavioral changes.
New exploratory research analyzed the association of lockdown measures on myopia progression and compared the performance of defocus incorporated multiple segments (DIMS) lens to a single vision lens (SVL) treatment in the reduction of this progression in children.
Led by Henry Ho-lung Chan, PhD, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, the team observed that myopia progressed more rapidly during the period of time with more COVID-19-related lockdowns, while also observing that optical treatment with DIMS had significant associations with slower myopia progression.
The cohort study utilized data from 2 independent, longitudinal studies, beginning in 2019. In study 1, DIMS lens treatment was prescribed to children in need who underwent regular eye examinations for 2 years. Study 2 was a randomized controlled trial, wherein the control group wearing SVL were included in the analysis.
Each study recruited schoolchildren aged 7 - 13 years, with participants undergoing scheduled eye examinations at the Optometry Research Clinic of the investigators’ institution. Analysis of the data was performed from June - July 2021.
As a result of the COVID-19 lockdown in Hong Kong, timing within the study often deviated from planned methods. In order to account for nonuniform study intervals, change from baseline in axial length (AL) and spherical equivalent refraction (SER) were proportionally adjusted to a 12-month change. The first visit from June 2019 and later was treated as baseline, with subsequent follow-up visits reviewed for refractive changes.
Additionally, since patients with baseline visits early after June 2019 may have spent less time in lockdown up to the follow-up visit, lockdown severity was increased for those with later baseline visits. Thus, the study populations were divided according to lockdown severity by median-splitting the percentage of time lockdown in between baseline and follow-up visits.
There were 115 participants (58 female, 50.4%) in the DIMS group and 56 participants (29 female, 51.8%) in the SVL group. Participants in the SVL group were half a year older (mean age, 10.3 years versus 10.8 years) and with milder myopia (mean baseline refraction, -2.99 D versus -4.02 D) compared to the DIMS group.
Data show both treatment type (DIMS versus SVL, 0.19 mm; 95% CI, 0.16 - 0.22 mm versus 0.30 mm; 95% CI, 0.25 - 0.35 mm; P <.001) and lockdown severity (less versus more time, 0.20 mm; 95% CI, 0.16 - 0.24 mm versus 0.29 mm; 95% CI, 0.25 - 0.32 mm, P = .001) were significantly associated with changes in AL, without a significant interaction association.
Then, for the change in SER, there were significant associations with treatment type (DIMS versus SVL, -0.31 D; 95% CI, -0.39 to -0.23 D versus -0.57 D; 95% CI, -0.69 to -0.45 D, P = .001) and lockdown severity (less time versus more time, -0.34 D; 95% CI, -0.44 to -0.25 D versus -0.54 D; 95% CI, -0.64 to -.44 D, P = .01).
In the interstudy comparison, DIMS lens treatment was significantly associated with a slower 12-month progression of AL and SER of 34% and 46%, respectively, in the overall population, independent of the severity of the lockdown.
“The results of the current analysis, along with others provide data sets from longitudinal cohort studies demonstrating that the lockdown policy resulted in increased myopia progression in school children,” investigators wrote.
The study, “Evaluation of an Optical Defocus Treatment for Myopia Progression Among Schoolchildren During the COVID-19 Pandemic,” was published in JAMA Network Open.