The Fan and block chart is similar to an astigmatism fan chart but additionally includes a block which contains an arrow at the center and two blocks of the line adjacent to the arrow which are perpendicular to one another. This additional block makes this test easier for the patient. Before reading procedure read optics … Read more
The astigmatism fan chart has line differences in 10 degrees intervals. Some charts have correcting cylinder axis marked in chart written at top of each spoke of line (Figure 1) and some charts just only represent the actual representation of line orientation in degree (Figure 2). We can easily find out whether correcting the cylindrical … Read more
Two of the most commonly used astigmatism chart are the Clock dial chart and the astigmatism fan chart. This test well controls accommodation as fogging is done prior and has an advantage over the Jackson cross cylinder where one of the focal lines is behind the retina which can disrupt the rest of the accommodation. … Read more