transposition

Cross cylinder to Spherocylinder

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Steps of the cross-cylinder to Spherocylinder Step 1: Choose either one cross cylinder out of two, as the sphere. Step 2: Subtract the cross-cylinder which was taken as the sphere from the other cylinder which was not taken as the sphere in step 1. Step 3: Axis of the sphero cylinder form is the same … Read more

Simple transposition

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It’s a method of converting spectacle prescriptions from one cylinder form to another i.e. plus cylinder to minus cylinder or vice-versa Steps of simple transposition: Step 1: Axis change: If the axis of the cylinder is equal or less than 90 degrees, add 90 degrees If the axis of the cylinder is more than 90 … Read more