Purchase this article with an account.
Zuopao Zhuo, Yuwen Wang, Jinhua Bao, Adeline Yang, Damien Paille, Hao Chen; Influence of prismatic round segment bifocals on posture during near tasks in Chinese myopic children. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5830.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The aim of this study was to investigate the influence of prismatic round segment bifocals (PRoSBi) on posture in Chinese myopic children as compared with single vision lens (SVLs).
17 myopic children aged 10 to 13 years (mean ± SD, 11.12 ± 1.02 years) participated in this study. Their refractive errors (spherical equivalent) ranged from -0.75D to -4.00D (-1.88 ± 0.73 D), and all of them had no prior history of any other myopia control solution. Two correction methods were used in sequential order in this study: first SVLs and second the PRoSBi (+2.00D addition combined with 3△ base-in prism, 2x3△ base-in prism in binocular). The tasks for each subject were to read Chinese stories on a standard A5-size paper including 15 lines with Chinese Song font, and to write Chinese on a standard A5-size paper including 7 lines. Participants’ postures during reading and writing were measured after at least one month adaptation to each correction method, using an electromagnetic motion tracking system (Fastrack, Polhemus, USA). Postural parameters such as working distance, head tilt angle, and ocular gaze angle were calculated for analysis.
For reading task, head tilt angle showed significant increase with PRoSBi (37.4 ± 8.1°) as compared to SVLs (30.2 ± 10.1°, P = 0.04), lens type had no effect on working distance (SVLs: 33.5 ± 3.7 cm; PRoSBi: 31.2 ± 6.1 cm, P = 0.18) and ocular gaze angle (SVLs: 22.2 ± 8.5°; PRoSBi: 19.1 ± 15.2°, P = 0.35). For writing task, lens type had no effect on working distance (SVLs: 25.1 ± 6.3 cm; PRoSBi: 25.3 ± 6.7 cm), head tilt angle (SVLs: 46.6 ± 11.6°; PRoSBi: 47.7 ± 11.7°), or ocular gaze angle (SVLs: 22.0 ± 7.9°; PRoSBi: 18.1 ± 11.4°) (all P > 0.24). Compared to reading task, working distance decreased and head tilt angle increased significantly in writing task (both P < 0.001), but near task had no effect on ocular gaze angle (P = 0.91).
Based on the amount of head tilt angle and ocular gaze angle after one month of adaptation to PRoSBi, the children in the study were using the near segment for reading and writing task. Children adopted shorter working distance and more head tilt angle during writing task than that of the reading task.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
This PDF is available to Subscribers Only