American Board of Ophthalmology (ABO) Practice Exam

When fitting lenses, how should the pantoscopic angle be adjusted?

1. More than 20 degrees

2. At least 5 degrees

3. Between 8 and 15 degrees

4. Under 5 degrees

The correct answer is: Between 8 and 15 degrees

In the context of fitting lenses, particularly for eyeglasses, the pantoscopic angle refers to the angle at which the lenses tilt towards the wearer's face when viewed from the side. Adjusting this angle correctly is critical for both comfort and optical performance. The correct choice, which cites a pantoscopic angle between 8 and 15 degrees, reflects the commonly accepted range for optimal lens positioning. This range is based on ensuring that the optical center of the lens aligns well with the wearer's pupils and that the lenses effectively project the desired visual correction. A tilt within this range helps in enhancing visual clarity and minimizing aberrations. When the angle is too steep (more than 20 degrees), it can lead to distorted vision and discomfort, as it positions the lenses too far outward. Conversely, an adjustment under 5 degrees may not adequately position the lenses to take advantage of their optical properties, negatively impacting visual acuity. The precise setting of the pantoscopic angle is essential for not just aesthetics, but also for achieving the best functional outcomes in lens performance.