Optical inhibition of axial myopia progression

Abstract

Abstract Purpose: The Dual‐focus Inhibition of Myopia Evaluation in New Zealand (DIMENZ) clinical trial tests the efficacy of myopic retinal defocus in slowing myopia progression. Methods: Dual‐focus (DF) soft contact lenses have a central correction zone and peripheral zones that cause 2.00D of simultaneous myopic retinal defocus during distance and near viewing. Children (12‐14 yrs, n=40, mean refractive error: ‐ 2.70D) were fitted with a DF lens in one eye and a single vision distance (SVD) lens in the fellow eye. After 10 mo. wear, lens assignment was swapped between eyes and the lenses worn for a further 10 mo. Accommodation was measured using an open‐field autorefractor. Myopia progression was monitored using cycloplegic autorefraction and partial coherence interferometry every 5 mo. Results: Visual acuity and contrast sensitivity of eyes wearing DF & SVD lenses were not different (p=0.209 & 0.157). When the DF lens was worn with either a single vision near (effective add = +2.50D) or a SVD lens in the fellow eye, children accommodated normally to a target at 40 cms. Preliminary results for 10 children after 10 mo. showed that the mean (± 1 SE) increase in myopia and axial length in eyes wearing the DF lens (‐0.45 ± 0.40D & 0.08 ± 0.079mm) were significantly less (p<0.0001 & 0.00002) than in eyes wearing the SVD lens (‐0.79 ± 0.41D & 0.21 ± 0.11 mm). Thus, DF lenses had a 12 mo. adjusted treatment effect of 0.40D & 0.15 mm. Conclusions: DF lenses provide normal acuity and contrast sensitivity. They do not alter accommodative response, so provide myopic retinal defocus at distance and near. Myopia progression is slowed significantly in eyes wearing DF lenses, suggesting that myopic defocus acts as an anti‐myopiagenic stimulus.