Abstract:
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Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce
myopic peripheral refractive error (PRE).
Methods: Zemax ray-tracing software was employed to simulate myopic ...[+]
Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce
myopic peripheral refractive error (PRE).
Methods: Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model
eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90–180 astigmatism J180, was computed at
different peripheral positions, ranging from 0 to 35 in steps of 5, and for different pupil diameters (PDs).
Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and
model eye accommodation. For comparison purposes, the same simulations were performed with another
commercially available contact lens designed for the same intended use: the Dual Focus (DF).
Results: PRE was greater with FCL than with DF when both designs were tested for a 3.5 mm PD, and with and
without decentration of the lenses. However, PRE depended on PD with both multizone lenses, with a
remarkable reduction of the myopic relative effect for a PD of 5.5 mm. The myopic PRE with contact lenses
decreased as the myopic refractive error increased, but this could be compensated by increasing the power
of treatment zones. A peripheral myopic shift was also induced by the FCLs in the accommodated model eye.
In regard to visual performance, a myopia under-correction with reference to the circle of least confusion
was obtained in all cases for a 5.5 mm PD. The ghost images, generated by treatment zones of FCL, were
dimmer than the ones produced with DF lens of the same power.
Conclusions: FCLs produce a peripheral myopic defocus without compromising central vision in photopic
conditions. FCLs have several design parameters that can be varied to obtain optimum results: lens diameter,
number of zones, addition and asphericity; resulting in a very promising customized lens for the treatment
of myopia progression.
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Thanks:
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This research was supported by the Ministerio de Economia y Competitividad (grant FIS2011-23175), the Generalitat Valenciana (grant PROMETEO2009-077) and the Universitat Politecnica de Valencia (grant INNOVA SP20120569), Spain.[+]
This research was supported by the Ministerio de Economia y Competitividad (grant FIS2011-23175), the Generalitat Valenciana (grant PROMETEO2009-077) and the Universitat Politecnica de Valencia (grant INNOVA SP20120569), Spain.
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