With excessive or unwanted base down prism:

Excessive or unwanted base down prism affects visual perception in a way that can cause distortions in how we perceive the height of objects and people. When base down prism is utilized or present more than is necessary, it shifts the perceived location of objects downward. As a result, when looking at people standing in front of you, they may appear taller than they actually are due to the visual distortion created by the prism. This is related to the manner in which the visual axis is altered, affecting depth perception and spatial awareness.

Understanding the nature of base down prism is crucial here. The prism, which displaces images, creates a scenario where linear perspective is altered, leading to the visual illusion of increased height. This effect is important for those working in ophthalmic dispensing or related fields, as it can impact how lenses are prescribed and how patients perceive their surroundings after adjustments are made to their prescriptions. Correctly interpreting the effects of prism helps in providing accurate advice and ensuring optimal visual comfort for patients.