In HAC correspondence, the objective angle equals the angle of anomaly. Which option best reflects this description?

• A. HAC (objective = angle of anomaly)
• B. Unharmonious correspondence
• C. PAC 1
• D. PAC 2

Answer: (A)

In anomalous retinal correspondence, different patterns describe how the brain adapts to prevent diplopia. In HAC, which stands for Hering's Anomalous Correspondence, the shift in retinal mapping (the angle of anomaly) matches exactly the measured misalignment of the eyes (the objective angle). So, the amount the brain changes which retinal point it uses for correspondence is the same as how far the eyes are misaligned in primary gaze. This direct equality is what defines HAC, making it the best fit for the description.

Other terms refer to different ARC patterns where the relationship between the shifted correspondence and the motor deviation isn’t a simple one-to-one equality, so they don’t match this description as cleanly.