Abstract
Purpose: :
Soft contact lenses can be designed to improve vision by controlling spherical aberration (SA). This study investigated the on-eye aberrations of six different contact lens designs to determine how the range of SA in a contact lens wearing population and the effects of on-eye lens decentration may limit potential benefits.
Methods: :
Three different lenses of each design with labelled powers -0.5 to 8.0D were measured in vitro in a wet cell using the ClearwaveTM aberrometer. Regression equations were obtained by plotting 3rd and 4th order aberrations versus labelled power for each design. Ocular aberrations of 75 myopes were measured over a 5mm analysis diameter using the COAS-HD aberrometer. On-eye aberrations were predicted for each lens power for the sample by adding the expected lens SA to the SA of the eye for each lens design. In addition two designs were decentred by 0.5mm for in vivo and in vitro comparison.
Results: :
In vitro
Conclusions: :
No lens design gave zero SA either in vivo or for predicted on-eye values, which is likely to induce unwanted coma due to commonly observed lens decentration. Results suggest that lenses could be designed more specifically to address factors such as decentration and variance in SA of subjects across the power range under investigation.