Effect of low-addition soft contact lenses with decentered optical design on myopia progression in children: a pilot study

Abstract

Purpose: To investigate the effect of low-addition soft contact lenses (CLs) with decentered optical design on the progression of myopia in children in a pilot study.

Subjects and methods: Twenty-four Japanese children age 10-16 years with baseline myopia of -0.75 to -3.50 D sphere and ≤1.00 D cylinder were studied. The new CLs were designed to have a nasal decentration with the optical center centered on the line of sight, and with progressive-addition power of +0.5 D peripherally. Monofocal soft CLs were used as controls. A pair of new CLs or control CLs was randomly assigned to the children, and they wore the lenses for 12 months during the first phase. Then, the type of CLs was changed, ie, a crossover design, and the children were observed for another 12 months during the second phase. The end points were changes in axial length and refractive error (spherical equivalent) under cycloplegia.

Results: The change of axial length in the new-CL and control-CL groups was not different between 12 months and baseline, the change of axial length between 12 months and 1 month in the new-CL group (0.09±0.08 mm) was significantly smaller (47%) than that in the control-CL group (0.17±0.08 mm, P<0.05). During the same period, the change of refractive error in the new-CL group was not significantly different from that in the control group. Neither the change in axial length nor refractive error in the new-CL group was significantly different from those in the control-CL group in the second phase.

Conclusion: This pilot study suggests that low-addition soft CLs with decentered optical design can reduce the degree of axial elongation in myopic children after an initial transient phase of CL wear. The reduction of the progression of myopia by low-addition soft CLs warrants further investigations.

Keywords: contact lens; myopia progression; prevention of myopia; progressive-addition lens.

Figure 1

Design of low-addition soft contact lens (CL). Notes: (A) Geometry of distance viewing and addition viewing zones. The CL was designed to have a decentered optical zone, with the center shifted 0.5 mm nasally from the geometric center of the lens. (B) The thick zones of the CL. To prevent CL rotation, it had horizontal thick zones.

Figure 2

Simulated relative contact lens (CL) power in the peripheral zone for the new-CL and the control-CL. In the new-CL, the theoretical refractive power of the lens increased progressively and positively to reach a relative positive power of +0.50 D at the edge of the peripheral zone. The control CLs were monofocal in design, and the theoretical relative refractive power of the lens increased negatively and progressively in the periphery. The short dashed line indicates the monofocal CL with spherical power of −1 D. The long dashed line indicates monofocal CL with spherical power of −3 D. The solid line indicates the new-CL.

Figure 3

Relative peripheral refractive error profile with new contact lenses (CLs). The relative peripheral refractive error profiles in eyes wearing new CLs, wearing control CLs, and naked eyes were compared during the second year of the trial after the crossover. The relative peripheral refraction was not different (Steel–Dwass) among naked eyes, eyes with new CLs, and eyes with the control CLs at any eccentricity.

Figure 4

Mean changes in the axial length from baseline to 24 months. The differences were not significant except at 1 month when the axial length elongated more in the new-CL group than in the control-CL group. Note: ^‡P<0.05, Wilcoxon rank sum. Abbreviations: CLs, contact lenses; ANOVA, analysis of variance.

Figure 5

Mean changes in the axial length from 1 month to 12 months. The changes were significantly lower at 3, 9, and 12 months in the new-CL group than in the control-CL group. Note: ^‡P<0.05, Wilcoxon rank sum. Abbreviations: CLs, contact lenses; ANOVA, analysis of variance.

Figure 6

Mean changes in the refractive error from baseline to 24 months. The differences were not significant, except at 1 month, where the refractive error increased more in the new-CL group than the control-CL group. Abbreviations: CLs, contact lenses; ANOVA, analysis of variance.

Figure 7

Mean changes in spherical equivalent refractive error from 1 month to 12 months. The changes in refractive error at 1 month were not significantly different between the new-CL group and the control-CL group. Abbreviations: CLs, contact lenses; ANOVA, analysis of variance.