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Thesis

The relation of cyclophoria to the difference between monocularly and binocularly measured axes of astigmatism at near.

2 August 1982

Abstract

The purpose of this research project is to determine the role cyclophoria plays when considering the differences between a monocular and a binocular refraction at forty centimeters. We are under the assumption that the eye is in its cyclophoric position while undergoing the monocular phase of the test, and is in its non-cyclophoric position while undergoing the binocular phase of the test. It was our contention that cyclophoria does exist and would play some role in the differences between a monocular and a binocular refraction. As a result, we would hypothesize that the rotation of the cylinder axes between the two refractions should correspond closely to the rotation of cyclophoria. ifuat our project has found is that cyclophoria does definitely play a role in the shift in axis from a binocular to monocular refraction, but this role varies in magnitude in each individual subject. The optometric implications of this research become significant when we consider patients who require astigmatic corrections, where a routinely monocularly refracted cylinder power and axis is prescribed, but where a different binocularly refracted cylinder power and axis might be more useful, since we function in this binocular mode the majority of the time. Our findings would suggest that this situation could exist in many cases, especially when cylinder powers are significant, and there is less tolerance for an imprecise axis measurement.


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