May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Short Periods of Plus Lens-Wear Overrides the Myopiagenic Effects of Minus-Lens Wear in Guineapigs
Author Affiliations & Notes
  • S. A. McFadden
    School of Psychology, University of Newcastle, Callaghan, Australia
  • R. Cuskelly
    School of Psychology, University of Newcastle, Callaghan, Australia
  • Footnotes
    Commercial Relationships S.A. McFadden, None; R. Cuskelly, None.
  • Footnotes
    Support None.
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 1532. doi:https://doi.org/
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      S. A. McFadden, R. Cuskelly; Short Periods of Plus Lens-Wear Overrides the Myopiagenic Effects of Minus-Lens Wear in Guineapigs. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1532. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose:: In chicks, very brief periods of positive spectacle lens-wear completely overshadows the myopiagenic effect of wearing minus lenses for the rest of the day. It is just as effective as inducing hyperopia as brief periods of plus lens-wear with normal vision without lenses for the rest of the day1. The amelioration of the effect of negative lenses by a plus lens is greater than a plano lens1. In contrast, in monkeys, briefly replacing a negative lens with plano lens is more effective than replacing it with a +4.5 D lens2, and in tree shrews, 45 mins of +3, +4 or +5D lens-wear, reduces the myopia arising from -5D lens-wear, but the vitreous depth is still greater in the lens-wearing eye and it does not develop relative hyperopia, and the potency is less than that provided by a plano lens substitution3. To determine if this is a chick-o-centric phenomena, we tested the potency of plus lenses in counteracting minus lenses in the near adolescent guinea pig.

Methods:: Guinea pigs wore -4D lenses on one eye from day 10-22 continuously for a 12 hr day (n=8), or had +4D lenses substituted during two 1 hr periods (n=6), or wore +4D and -4D lenses for an equal amount of time in 3 hr periods (n=8). At 22 days of age, refractive error (streak retinoscopy) and corneal power (infrared videokeratometry) were measured in awake cyclopleged animals, and ocular parameters determined using high frequency ultrasound under anaesthesia.

Results:: After 12 days, continuous minus lens wear resulted in relative myopia (-1.41±1.3D) and longer axial lengths (+50±17 µm) as expected4. In contrast, every guinea pig which had +4D lenses substituted for 1 hr periods had shorter axial lengths (mean, -36±17µm) and on average were relatively hyperopic (+1.04±0.6D). This induced hyperopia required short periods of exposure, as longer 3 hr periods were not as effective in counteracting the myopia from minus lens-wear (reduced to -0.19±0.7D).

Conclusions:: Contrary findings between chicks and mammals may be related to the timing of lens-exposure. If children are like guinea pigs, then we predict that the equivalent of multiple short periods of positive spectacle lens-wear will be effective in counteracting minus lens-wear, while longer periods will be less effective.1. Zhu X, Winawer JA, Wallman J. Invest Ophthalmol Vis Sci. 2003 44(7):2818-27.2. Kee C-S, Hung L-F, Qiao Y, Ramamirtham R, Winawer JA, Wallman J, Smith EL, ARVO Abstract 2925, 2002.3. Norton TT, Siegwart JT Jr, Amedo AO. Invest Ophthalmol Vis Sci. 2006 47(11):4687-99.4. McFadden SA, Howlett MH, Mertz JR. Vision Res. 2004 44(7):643-53.

Keywords: myopia • refractive error development • hyperopia 
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