OPTICAL CONSIDERATIONS

Consider the following patient:

Spectacle Rx: -2.00 = -1.75 x 180
K-reading: 43.00 @ 180; 43.75 @ 090

With a non-flexing spherical rigid lens on this eye 0.75 D. of the cylinder would be corrected (43.75 - 43.00) leaving 1.00 D.C. uncorrected.

With a spherical hydrogel lens on the eye -1.75 D.C. would be uncorrected.

Neither a spherical rigid or hydrogel lens would fully correct the patient.

In this case the most efficient method of correcting the patient would be to use a toric hydrogel lens.  A rigid prism ballasted front surface cylinder lens could be used, however, the success with this type of lens is often less than the toric hydrogel.