2 results for Anstice, Nicola, Doctoral

  • Dual-focus Inhibition of Myopia Evaluation in New Zealand

    Anstice, Nicola (2009)

    Doctoral thesis
    The University of Auckland Library

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  • Dual-focus inhibition of myopia evaluation in New Zealand

    Anstice, Nicola (2009)

    Doctoral thesis
    The University of Auckland Library

    Purpose: The Dual-focus Inhibition of Myopia Evaluation in New Zealand (DIMENZ) clinical trial tests the efficacy of myopic retinal defocus in slowing axial myopia progression. Methods: Dual-focus (DF) soft contact lenses were designed having a central zone correcting refractive error and peripheral treatment zones that caused 2.00D of simultaneous myopic retinal defocus. 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 was monitored using cycloplegic autorefraction and partial coherence interferrometry every 5 mo. Results: For DF lens-wearing eyes mean (± 1 SD) acuity was 99.85 ± 3.53) and for SV lens-wearing eyes 100.20 ± 2.87 (p = 0.209). After 10 months of CL wear mean (± 1 SD) increase in myopia and axial length in eyes wearing the DF lens (-0.441 ± 0.326 & 0.110 ± 0.084) were significantly less (p < 0.001) than in eyes wearing the SVD lens (-0.677 ± 0.405 & 0.218 ± 0.089). Thus, DF lenses had a 12 month adjusted treatment effect of 0.28D & 0.13 mm. Accommodative response was measured through the SVD lens and through a single vision near (SVN) lens (+2.50 D add) that reduced the accommodative demand to zero. When children changed their gaze from 4 m to 40 cm, accommodation increased by 1.80 ± 0.37 D when wearing a DF lens with a SVD lens and by 1.62 ± 0.59 with a DF and SVN contact lens (no significant difference, p = 0.21). Conclusion: Myopia progression is slowed significantly in eyes wearing DF lenses. This suggests that a myopically defocused image, even when presented to the retina simultaneously with a clear image, acts to slow myopia progression in children. DF lenses provide normal acuity and do not alter accommodative response, so provide myopic retinal defocus at distance and near.

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