Morgan's norms refer to the expected findings during smooth vergence testing expressed as which of the following?

• A. Expected blur, break, and recovery values
• B. Expected reaction times
• C. Color discrimination thresholds
• D. Stereopsis acuity thresholds

Answer: (A)

Morgan’s norms provide the expected reference values for what you should see during smooth vergence testing, specifically the sequence of when the target becomes blurred, when single vision is lost (break), and when single vision returns again (recovery). As you gradually add prism to increase vergence demand, the first indicator of a limit is blur—the point at which accommodation can no longer keep the image clear. Increase the demand further and you reach the break point, where the eyes can no longer maintain single binocular vision. Then as you lessen the demand, single vision returns at the recovery point. These three thresholds—blur, break, and recovery—are the normative data Morgan’s norms describe, so clinicians can compare a patient’s responses to typical values and identify binocular vision dysfunctions.

The other options don’t fit because Morgan’s norms are not about reaction times, color discrimination thresholds, or stereopsis acuity. Those are different aspects of vision testing, not the motor vergence response captured in smooth vergence testing.