2008-14 Scantling, Edmonson 1 |
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OPT 7062
Optometry Project III
Masking Astigmatism with Soft Contact Lenses
Ashley Scantling*, William Edmondson†
August 1, 2008
ABSTRACT
Background. Contact lens patient studies have demonstrated spherical PureVision silicone-hydrogel
lenses have an ability to mask astigmatism. Recently, Bausch and Lomb reduced the
modulus (lens stiffness) of the PureVision spherical contact lens from 1.6 MPa to a softer, more,
pliable 1.06 MPa to improve comfort.
The purpose of this study is to compare the amount of refractive astigmatism masked in patients
currently wearing the original, stiffer PureVision spherical silicone-hydrogel lenses with the
updated PureVision softer spherical silicone-hydrogel lenses.
Methods. All eyes in this study had spectacle refractive errors with 1.25 D or less initial refractive
cylinder. For each of the 26 eyes fitted with both the original, stiffer PureVision lens and the new,
softer (modulus 1.06 MPa) PureVision, residual astigmatism was compared by subjective over-refraction
to that noted with the original PureVision higher modulus lens by a t-test for a difference
of means. The percentage of spectacle best visual acuity cylinder masked was compared for
each type of lens. We also compared the masking ability for higher power lenses ±4.00D and
greater.
Results. The reduction in stiffness or modulus for spherical PureVision from 1.6MPa to 1.06MPa
did not significantly affect the amount of or percentage of astigmatism masked by the lenses. This
held true for both eyes with -0.50 D or less of refractive cylinder as well as for eyes wearing
lenses with greater than +/- 4.00D of sphere power.
Conclusion. Our data supports earlier reports that neither lens material, modulus (stiffness) nor
lens power (thickness) affect the ability of a non-toric soft contact lens to mask astigmatism. This
study supports previous findings that some specific aspheric contact lenses do mask refractive
astigmatism.
Keywords: PureVision, astigmatism, toric contact lenses
_____________________________
*BS
†MAT, OD, FAAO
Northeastern State University Oklahoma College of Optometry
Object Description
Description
| Title | 2008-14 Scantling, Edmonson 1 |
| Contents | OPT 7062 Optometry Project III Masking Astigmatism with Soft Contact Lenses Ashley Scantling*, William Edmondson† August 1, 2008 ABSTRACT Background. Contact lens patient studies have demonstrated spherical PureVision silicone-hydrogel lenses have an ability to mask astigmatism. Recently, Bausch and Lomb reduced the modulus (lens stiffness) of the PureVision spherical contact lens from 1.6 MPa to a softer, more, pliable 1.06 MPa to improve comfort. The purpose of this study is to compare the amount of refractive astigmatism masked in patients currently wearing the original, stiffer PureVision spherical silicone-hydrogel lenses with the updated PureVision softer spherical silicone-hydrogel lenses. Methods. All eyes in this study had spectacle refractive errors with 1.25 D or less initial refractive cylinder. For each of the 26 eyes fitted with both the original, stiffer PureVision lens and the new, softer (modulus 1.06 MPa) PureVision, residual astigmatism was compared by subjective over-refraction to that noted with the original PureVision higher modulus lens by a t-test for a difference of means. The percentage of spectacle best visual acuity cylinder masked was compared for each type of lens. We also compared the masking ability for higher power lenses ±4.00D and greater. Results. The reduction in stiffness or modulus for spherical PureVision from 1.6MPa to 1.06MPa did not significantly affect the amount of or percentage of astigmatism masked by the lenses. This held true for both eyes with -0.50 D or less of refractive cylinder as well as for eyes wearing lenses with greater than +/- 4.00D of sphere power. Conclusion. Our data supports earlier reports that neither lens material, modulus (stiffness) nor lens power (thickness) affect the ability of a non-toric soft contact lens to mask astigmatism. This study supports previous findings that some specific aspheric contact lenses do mask refractive astigmatism. Keywords: PureVision, astigmatism, toric contact lenses _____________________________ *BS †MAT, OD, FAAO Northeastern State University Oklahoma College of Optometry |
