If a patient feels like they are walking uphill on a flat surface, what could be the likely cause?

When a patient experiences the sensation that they are walking uphill on a flat surface, this perception can be linked to the use of prism in their lenses. The specific situation described often arises when there is too much base up prism incorporated into the lenses. Base up prism can create a visual perception that objects are positioned higher than they actually are, altering the visual field in a way that makes flat surfaces seem inclined. This altered perception can lead to feelings of imbalance or disorientation, resulting in the sensation of walking uphill.

In contrast, while a base down prism might lead to a different type of misperception, it does not typically cause the sensation of walking uphill; instead, it could create feelings of walking downhill or impact depth perception in a way that is different from base up. An incorrect lens prescription or defective lens can also lead to visual disturbances, but they would not specifically produce the sensation of an incline as effectively as an excess of base up prism would. Therefore, identifying the correct cause is essential for appropriate intervention and patient comfort.