The effect of peripheral defocus on axial growth and modulation of refractive error in hyperopes

Abstract

To establish whether axial growth and refractive error can be modulated in hyperopic children by imposing relative peripheral hyperopic defocus using multifocal soft contact lenses. Methods:A prospective controlled study with hyperopic participants allocated to a control or test group. Control group participants were corrected with single vision spectacles and changes to axial length and refractive error were followed for 3 years. For the test group, axial growth and post-cycloplegic refractive error were observed with participants wearing single vision spectacles for the first 6 months of the trial and then corrected with centre-near multifocal soft contact lenses with a 2.00 D add for 2 years. The central 'near' portion of the contact lens corrected distance refractive error while the 'distance' portion imposed hyperopic defocus.Participants reverted to single vision spectacles for the final 6 months of the study.Results: Twenty-two participants, mean age 11.13 years (SD 1.72) (range 8.33-13.92), completed the trial. Axial length did not change during the first 6 months in either group (p = 1.00). Axial growth across the 2-year intervention period was 0.17 mm (SEM 0.04) (p < 0.0005) in the test group versus 0.06 mm (SEM 0.07) (p = 0.68) in the control group. Axial length was invariant during the final 6 months in either group (p = 1.00). Refractive error was stable during the first 6 months in both groups (p = 1.00). Refractive error change across the 2-year intervention period was −0.26 D (SEM 0.14) (p = 0.38) in the test group versus −0.01 D (SEM 0.09) (p = 1.00) in the control group. Neither the test (p = 1.00) nor control (p = 0.63) group demonstrated a change in refractive error during the final 6 months. Conclusions: The rate of axial growth can be accelerated in children with hyperopia using centre-near multifocal soft contact lenses. K E Y W O R D S axial growth, contact lenses, hyperopia, peripheral defocus, refractive error | 535 EFFECT OF DEFOCUS ON AXIAL GROWTH IN HYPEROPES F I G U R E 1 Schematic to demonstrate the concept of relative peripheral hyperopic defocus (RPHD) imposed with a centre-near bifocal contact lens (CL), while full refractive error is corrected centrally

Effect of peripheral defocus on axial growth and modulation of refractive error in children with anisohyperopia

“…Intriguingly, the AL in the control eye did increase over the trial period, and in fact, the interocular difference in AL was greater at the point of exit from the trial than at baseline. The findings here are in contrast to similar work with isohyperopes 16 where axial growth accelerated with the imposition of RPHD.…”

“…Inclusion and exclusion criteria are summarised in Table 1 and are in line with earlier work in children with isohyperopia. 16 Full details of primary and secondary outcomes' measures, including time points, are provided in Tables 2-5 and Figures 2 and 3. Key parameters…”

“…Until recently, 16 attempts to modulate refractive error in children with hyperopia have been absent from the literature and remain unaddressed in those with anisohyperopia.…”

“…More recently, work from the present authors has shown the ability to accelerate axial growth in children with isohyperopia using centre-near multifocal contact lenses to impose relative peripheral hyperopic defocus (RPHD). 16 The ability to modulate refractive error and axial growth in children with anisohyperopia by imposing RPHD has not yet been tested. Given that axial growth can be accelerated in children with isohyperopia by imposing hyperopic defocus using multifocal contact lenses, 16 applying a similar principle to anisohyperopes is a natural extension to this work.…”

“…16 The ability to modulate refractive error and axial growth in children with anisohyperopia by imposing RPHD has not yet been tested. Given that axial growth can be accelerated in children with isohyperopia by imposing hyperopic defocus using multifocal contact lenses, 16 applying a similar principle to anisohyperopes is a natural extension to this work.…”