Most impoant use of cross cylinder is -
Answer- A. Verify the strength and axis of the cylinderThe proper subjective refraction includes three steps-I) Subjective verification of refractionThe strongest convex lens and the weakest concave lens providing best vision should be chosen in patients with hypermetropia and myopia respectively.2) Subjective refning of refractionA) Refining the cylinder : - Cylinder can be refined by either crosscylinder or by astigmatic fan test.Jackson's cross cylinder test (more commonly used)- crosscylinder is used to verify the strength and axis of the cylinder prescribed.Astigmatic fan test:- It is used to confirm the cylindrical correction.B) Refining the sphere- The fogging technique, Duochrome test, Pin-hole test.3) Subjective binocular balancing.
Verify the strength and axis of the cylinder
Refining the sphere
Binocular balancing
Retinoscopy