Changes in Stress-Strain Index in School-Aged Children: A 3-Year Longitudinal Study
Table 4
Changes in stress-strain index among the refractive groups.
PNM (n = 92)
NDM (n = 97)
PM (n = 28)
value
SSI
Baseline
Median (range)
1.02 (0.93, 1.12)
1.01 (0.91, 1.09)
0.95 (0.86, 1.06)
0.047
Follow-up
Median (range)
0.98 (0.89, 1.06)
0.90 (0.81, 0.98)
0.85 (0.81, 0.91)
<0.001
Change
Median (range)
−0.05 (−0.14, 0.03)#
−0.13 (−0.22, −0.01)#
−0.09 (−0.14, −0.06)#
0.016
AL (mm)
Baseline
Median (range)
22.72 (22.47, 23.14)
22.97 (22.43, 23.52)
23.78 (23.09, 24.18)
<0.001
Follow-up
Median (range)
23.37 (22.96, 23.71)
24.13 (23.59, 24.75)
24.85 (24.57, 25.51)
<0.001
Change
Median (range)
0.51 (0.43, 0.65)#
1.15 (0.9, 1.35)#
1.16 (1.02, 1.48)#
<0.001
SE (D)
Baseline
Median (range)
1.25 (1, 1.5)
0.63 (0.5, 1)
−1.19 (−2, −0.63)
<0.001
Follow-up
Median (range)
0.25 (0, 0.75)
−1.5 (−2.5, −0.88)
−3.38 (−4.59, −3)
<0.001
Change
Median (range)
−0.94 (−1.25, −0.63)#
−2.25 (−2.88, −1.75)#
−2.38 (−2.63, −2.19)#
<0.001
AL, axial length; SE, spherical equivalent; SSI, stress-strain index; NDM, newly developed myopia; PM, persistent myopia; PNM, persistent nonmyopia. Statistical significance was tested using Kruskal–Wallis H. #, compared between baseline and follow-up within the group tested using a Wilcoxon test.
