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GP lens provides myopic relative peripheral refractive error
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A novel gas-permeable contact lens induced relative peripheral myopic defocus, according to a study recently published in Optometry and Vision Science.
Pauné and colleagues evaluated the right eyes of 52 patients with myopia to assess the efficacy of an experimental gas-permeable lens (ExpRGP) compared to a standard GP (StdRGP) design.
The participants’ spherical refractive errors ranged from −0.75 D to −8.00 D, and their refractive astigmatism was 1.00 D or less.
Researchers used an open-field autorefractometer to measure the relative peripheral refractive error (RPRE) of the participants with no lens, with the experimental GP and with the standard GP.
As detailed in the study, the GP lenses were made of Boston XO2 (hexafocon B). The standard GP lenses were a commercial lens, PRE AS (Precilens, France). The experimental GP lenses were created using Zemax-EE software v.6 (Radiant ZEMAX).
Results showed that the experimental lenses created significant change in RPRE compared to not wearing lenses; 60% of eyes had peripheral myopia exceeding −1.00 D when wearing the experimental lens while no eyes demonstrated this at baseline. Researchers also reported no significant correlation between baseline refractive error and the amount of induced myopia.
"The current study showed for the first time that a custom GP lens might effectively induce relative peripheral myopic defocus across a wide range of values of axial myopia," the authors wrote. "Contrary to the relationship between induced peripheral myopic defocus and central refractive error in orthokeratology treatments, the amount of myopia induced in the periphery of the visual field with the lens evaluated in the present study is not limited by, or related to, the axial refraction." – by Chelsea Frajerman Pardes
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