What are the Morgan's norms for Distance BI smooth vergences?

What are the Morgan's norms for Distance BI smooth vergences?

• A. -----/7/4
• B. 9/19/10
• C. 13/21/13
• D. 17/21/11

Answer: (A)

Morgan's norms give the typical fusional vergence limits at distance and near, telling you how much divergence or convergence a person can maintain before diplopia appears and how well they recover after the prism is removed. For distance base-in (BI) smooth vergences, the expected values are a break around 7 prism diopters and a recovery around 4 prism diopters. The dash before the numbers indicates there isn’t a blur value reported for this measure in this norm set, since smooth BI vergence testing focuses on break and recovery rather than a separate blur threshold. So the standard presentation is a dash for blur, then 7 for break, and 4 for recovery. The other reported sets would imply much larger ranges than Morgan's norms indicate for distance BI, which is why they don’t fit.

Morgan's norms give the typical fusional vergence limits at distance and near, telling you how much divergence or convergence a person can maintain before diplopia appears and how well they recover after the prism is removed. For distance base-in (BI) smooth vergences, the expected values are a break around 7 prism diopters and a recovery around 4 prism diopters. The dash before the numbers indicates there isn’t a blur value reported for this measure in this norm set, since smooth BI vergence testing focuses on break and recovery rather than a separate blur threshold. So the standard presentation is a dash for blur, then 7 for break, and 4 for recovery. The other reported sets would imply much larger ranges than Morgan's norms indicate for distance BI, which is why they don’t fit.