Highly aspherical lenslets may reduce myopia progression and axial elongation with higher efficacy: JAMA
Prevalence rates of myopia and high myopia are alarming. Myopia control interventions have been used for many years to reduce the severity of myopia and decrease the risk of associated ocular pathologies. Increasing evidence suggests that specifically designed optical interventions such as spectacle lenses, soft contact lenses, and orthokeratology slow myopia progression in children. The common features of these myopia optical interventions are to provide central correction for distance vision and correct peripheral retinal defocus or induce peripheral myopic retinal defocus simultaneously. Peripheral visual signals have been found to dominate central refractive development, and the effect of peripheral myopic retinal defocus was found to provide myopia control signals.
This study by Jinhua Bao and team evaluate novel spectacle lenses with aspherical lenslets and explores the effect of lenslet asphericity on myopia control efficacy. The results from the first-year interim analysis showed that spectacle lenses with highly aspherical lenslets (HAL) and spectacle lenses with slightly aspherical lenslets (SAL) were effective in slowing myopia progression. Moreover, a dose-dependent response was observed, as HAL had significantly better myopia control effect than SAL.
Study aimed to evaluate whether spectacle lenses with aspherical lenslets still slow myopia progression over 2 years and whether the level of lenslet asphericity would still affect myopia control efficacy in a dose-dependent manner.
This double-masked randomized clinical trial was conducted between July 2018 and October 2020 at the Eye Hospital of Wenzhou Medical University in Wenzhou, China. Children aged 8 to 13 years with a cycloplegic spherical equivalent refraction (SER) of −0.75 D to −4.75 D and astigmatism with less than −1.50 D were recruited. A data and safety monitoring committee reviewed findings from a planned interim analysis in 2019.
Participants were randomly assigned in a 1:1:1 ratio to receive spectacle lenses with highly aspherical lenslets (HAL), spectacle lenses with slightly aspherical lenslets (SAL), or single-vision spectacle lenses (SVL).
Of 157 participants who completed each visit, 54 were analyzed in the HAL group, 53 in the SAL group, and 50 in the SVL group. Mean (SE) 2-year myopia progression in the SVL group was 1.46 (0.09) D. Compared with SVL, the mean (SE) change in SER was less for HAL (by 0.80 [0.11] D) and SAL (by 0.42 [0.11] D; P .001). The mean (SE) increase in axial length was 0.69 (0.04) mm for SVL.
Compared with SVL, increase in axial length was slowed by a mean (SE) of 0.35 (0.05) mm for HAL and 0.18 (0.05) mm for SAL (P .001). Compared with SVL, for children who wore HAL at least 12 hours every day, the mean (SE) change in SER was slowed by 0.99 (0.12) D, and increase in axial length slowed by 0.41 (0.05) mm.
In this 2-year randomized clinical trial, HAL slowed myopia progression by 0.80 D (55%) and increase in axial length by 0.35 mm (51%) compared with SVL. Compared with SAL, HAL slowed myopia progression by 0.38 D (37%) and axial length by 0.17 mm (33%). This outcome is well in line with the first year interim analysis, and it confirms a positive dose response relationship between myopia control efficacy and lenslet asphericity. The dose-dependent effect of optical interventions in minimizing lens-induced myopia in animal studies was attributed mainly to lens design features such as the amount and area of lens addition,19,20 peripheral defocus, and lens asphericity. This dose-dependent relationship was also found in human clinical studies for ophthalmic lenses with higher addition and contact lenses with higher asphericity. Compared with SVL, during the second year, HAL remained effective in slowing myopia progression. This was not the case for SAL that slowed myopia progression of children mainly during the first year.
In children with myopia, wearing HAL significantly reduced the rate of myopia progression and eye growth over 2 years compared with SAL and SVL. This study demonstrated a dose dependent effect, with higher lenslet asphericity having greater myopia control efficacy. The full-time wearing of HAL increased myopia control efficacy to 0.99 D (67%) for SER and 0.41 mm (60%) for axial length.
Source: Jinhua Bao, PhD; Yingying Huang, MD; Xue Li, PhD; JAMA Ophthalmol. doi:10.1001/jamaophthalmol.2022.0401
