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New laser meridional refractometry technique (RMA) as a tool to study irregular (non-toric) astigmatism and the Sine-Square law

20 May 1990


A new refractive technique is reported that uses a stenopaeic slit with laser light to enable spherical lens neutralization of equally spaced meridians of the test eye. Due to the finite width of the slit, the subject can observe cross sections of a modified conoid of Sturm by laser light reflected from a stationary diffusing surface. The endpoint for a given meridian is reached when appropriate sphere power places the center of the modified conoid on the retina, resulting in perception of minimum conoid cross section size. This technique is referred to here as Running Meridional Analysis (RMA). The goal of this research was to use RMA to test the validity of general application of the ''Sine Squared Law" to astigmatic eyes regardless of the amount of astigmatism. Suggestions are offered on application of RMA to contact lens over-refractions.


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