Purpose To report the results of 12-month wear of three novel spectacle lens designs intended to reduce peripheral hyperopic defocus and one standard design control lens and their effect on the progression of myopia in Chinese children aged 6 to 16 years. Methods Chinese children (n = 210) with myopia (−0.75 D to −3.50 D sphere, cylinder ≤−1.50 D) were randomized to one of four groups wearing either one of three novel spectacle lens designs (types I, II, or III) or conventional, single-vision spectacle lenses. Data were collected at 6 and 12 months. Primary and secondary outcome measures were the changes in central cycloplegic auto-refraction and eye axial length, respectively. Peripheral refraction along the horizontal meridian (nasal and temporal) was taken at baseline with and without spectacle lenses. Multivariate linear regression was used to adjust analyses for important covariates. Results Progression in eyes wearing control spectacle lenses at 6 and 12 months was −0.55 D ± 0.35 D and −0.78 ± 0.50 D, respectively. For the entire group, no statistically significant differences were observed in the rates of progression with the novel designs in comparison to control spectacle lenses. However, in younger children (6 to 12 years) with parental history of myopia (n = 100), there was significantly less progression (−0.68 D ± 0.47 D vs. −0.97 D ± 0.48 D) with lens type III compared with control spectacles (mean difference, 0.29 D, std error, 0.11, p = 0.038). Conclusions There were no statistically significant differences in the rate of progression of myopia between the control and novel lens wearing eyes for the age group 6 to 16 years. The finding of reduced progression of myopia with type III lens design in younger children with parental myopia needs to be validated in a more targeted study.

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Most of the commercial advances in the spectacle correction of presbyopia continue to occur in progressive lens design, which has been the focus of intense research and development over the past 60 years by major spectacle lens manufacturers. While progressive lens design and manufacturing techniques have advanced at a steady pace, recent progress in 'free-form' lens surfacing has opened up many exciting possibilities that will in all likelihood bring about a paradigm shift in the current model of progressive lens fabrication and distribution. The first instalment of this two-part series will review the fundamental optical principles and early development work associated with progressive lenses.

We investigated the limits at which blur due to defocus, crossed-cylinder astigmatism, and trefoil became noticeable, troublesome or objectionable. Black letter targets (0.1, 0.35 and 0.6 logMAR) were presented on white backgrounds. Subjects were cyclopleged and had effectively 5mm pupils. Blur was induced with a deformable, adaptive-optics mirror operating under open-loop conditions. Mean defocus blur limits of six subjects with uncorrected intrinsic higher-order ocular aberrations ranged from 0.18+/-0.08 D (noticeable blur criterion, 0.1 logMAR) to 1.01+/-0.27 D (objectionable blur criterion, 0.6 logMAR). Crossed-cylinder astigmatic blur limits were approximately 90% of those for defocus, but with considerable meridional influences. In two of the subjects, the intrinsic aberrations of the eye were subsequently corrected before the defocus and astigmatic blur were added. This resulted in only minor reductions in their blur limits. When assessed with trefoil blur and corrected intrinsic ocular aberrations, the ratio of objectionable to noticeable blur limits in these two subjects was much higher for trefoil (3.5) than for defocus (2.5) and astigmatism (2.2).