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Takehiro Yamashita, Naoya Yoshihara, Naoko Kakiuchi, Taiji Sakamoto; Axial elongation rate in eyes of junior high school students. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2132. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
It is well known that growing speed of axial length decreases with ageing time in children. On the other hand, there are some children whose myopia progresses rapidly during late growth period, such as junior high school age. This indicates that there may be some eyes whose axial elongation speed may increase conversely during late growth period. Therefore the purpose of this study was to see the growing speed of axial length during later growth period.
A prospective cohort study comprised 163 right eyes. All participants underwent optical axial length measurement at 1st, 2nd and 3rd grade of junior high school. The growth of axial length was determined by subtracting the axial length of two different time points. Growth of first half period was calculated by 2nd year result minus 1st year result (first growth). That of second half was calculated by 3rd year result minus 2nd year result (second growth). Then, growth rate change was obtained by the second growth being subtracted by the first growth in each eye. Eyes were classified into the followings, eyes with growth rate change less than -0.05 mm (deceleration), -0.05 to 0.05 mm (constant), and more than 0.05 mm (acceleration). Mann-Whitney U test was used to detect the difference between first and second growth and Spearman’s correlation was used to investigate the correlation between growth rate change and first grade axial length.
Mean axial length at first grade was 24.55 ±1.21 mm. The first growth (mean ± SD: 0.17 ±0.12 mm) was significantly larger than that of second growth (0.12 ±0.09 mm) (P<0.001). Seventy eyes were categorized as deceleration group, 67 eyes was constant group and the remaining 26 eyes as acceleration group. There was a significant and negative correlation between the growth rate change and first grade axial length (r=-0.41, P<0.01).
Growth rate of axial elongation was accelerated in 16.0% during junior high school time. The eye with short axial length at first grade was tended to accelerate the axial elongation during this period.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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