Cross Cylinder
An autorefractor or retinoscopy may provide an objective estimate of the eye's refractive error and the use of Jackson cross cylinders in a phoropter may be used to subjectively refine those measurements.An alternative technique with the phoropter requires the use of a "clock dial" or "sunburst" chart to determine the astigmatic axis and power.
Diopter: cyl -0.25, 0.50
Lens Q'ty: 2 lens
Case: Black Case
..
$12.26
Diopter: cyl -0.25, 0.50
Lens Q'ty: 2 lens
Case: Wooden Case
..
$9.19
Diopter: cyl -0.25, 0.50
Lens Q'ty: 2 lens
Case: Plastic Case
..
$17.93
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