What is the critical meridian of total lens when addressing vertical imbalance?

The critical meridian of total lens when addressing vertical imbalance is the 90-degree meridian. This relates to how lenses are oriented and the resulting effect of any prismatic imbalance between the two eyes.

In cases of vertical imbalance, it is essential to consider how the vertical powers of the lenses lead to differences in image height when viewed by each eye. At the 90-degree meridian, any vertical imbalance can produce a clear difference in the perceived image position, significant enough to cause discomfort or visual disturbances. This is particularly critical because vertical prisms can produce substantial shifts in the vertical position of the images seen through the lenses.

When dealing with vertical imbalance, understanding the orientation of the lens powers and how they interact at different meridians allows practitioners to effectively address potential issues related to image position. The focus at the 90-degree meridian specifically helps clinicians ensure that any vertical imbalance is minimized and the patient experiences clear, comfortable vision.