ABO Advanced Practice Test 2026 – Complete Exam Prep

Poor pupillary distance (PD) measurements can significantly affect the accuracy of optical prescriptions, leading to various issues. One of the primary consequences of inaccurate PD measurements is the misalignment of optical centers in lenses, which can create prism effects. When the PD is not correctly measured for a patient, it can result in the lenses inducing unwanted prism, causing one lens to be oriented at an angle that is inappropriate for the patient's line of sight. This leads to the application of base in or base out prisms, affecting how light enters the eye and how images are perceived.

In contrast, while blurred vision, vertical imbalance, and increased light transmission are certainly possible concerns related to general vision problems or lens fitting, they don't directly stem from pupil distance mismeasurement the way that prism effects do. The induced prism caused by improper PD directly correlates with the misalignment of visual axes, which is central to this issue.