What does 'With the Rule' (WTR) indicate about the power distribution in astigmatism?

What does 'With the Rule' (WTR) indicate about the power distribution in astigmatism?

• A. More power in the horizontal meridian
• B. Even power across all meridians
• C. More power in the vertical meridian
• D. Less power in the vertical meridian

Answer: (C)

The term "With the Rule" (WTR) in astigmatism refers to a specific orientation of the principal meridians of refractive error, where the steepest curvature is found in the vertical meridian. This characteristic implies that there is more optical power in the vertical meridian compared to the horizontal meridian. In practical terms, when an individual has astigmatism classified as WTR, they would typically experience more significant blurriness or distortion in the horizontal direction because the vertical meridian focuses light more sharply than the horizontal one. This is significant in diagnosing and correcting astigmatism, as it informs the optometrist or ophthalmologist of how to prescribe lenses that counteract this power imbalance. Understanding the orientation of astigmatism is crucial for effective treatment. Thus, the concept of WTR directly correlates with the observation of more power being present in the vertical meridian.

The term "With the Rule" (WTR) in astigmatism refers to a specific orientation of the principal meridians of refractive error, where the steepest curvature is found in the vertical meridian. This characteristic implies that there is more optical power in the vertical meridian compared to the horizontal meridian.

In practical terms, when an individual has astigmatism classified as WTR, they would typically experience more significant blurriness or distortion in the horizontal direction because the vertical meridian focuses light more sharply than the horizontal one. This is significant in diagnosing and correcting astigmatism, as it informs the optometrist or ophthalmologist of how to prescribe lenses that counteract this power imbalance.

Understanding the orientation of astigmatism is crucial for effective treatment. Thus, the concept of WTR directly correlates with the observation of more power being present in the vertical meridian.