The Effect Of Soft Lens Manufacture On Contrast Sensitivity.

There are two kinds of measures used to assess the resolving power of the visual system, those being, visual acuity and contrast sensitivity. Visual acuity measuring, tests resolving power by determining the smallest detail of a pattern that can be detected. Contrast sensitivity assesses resolving power by determining the minimum contrast needed to perceive a particular pattern. A sinusoidal grating pattern is commonly used, where
the difference between the light and dark bars can be reduced or increased, The difference at which the gratings are just resolved is the contrast threshold, and the reciprocal of the threshold is the contrast sensitivity Contrast sensitivity is greatest for patterns of intermediate frequency only, the low spatial frequencies are attenuated due to the nonlinearity
of the human visual system's transfer function. Curves of contrast sensitivity functions show that grating acuity is a single point on the function. Arden gratings are commonly used in contrast sensitivity testing, but they are time consuming and difficult to quantify. In this study
a computer was used with a cathode ray screen to generate the gratings and to record all data. Soft contact lenses, can be made in a variety of fashions, and in many different polymers . This study was conducted to determine if a particular design of a soft contact lens could markedly affect a subject's contrast sensitivity, comparably to another design of soft contact lens.