If a rigid lens was ordered with a base curve of 7.84 mm but received a lens measuring 7.94 mm, how does this lens compare to what was ordered?

The base curve of a rigid contact lens is a critical factor affecting its fit on the cornea and the overall visual acuity it provides. In this scenario, the ordered base curve is 7.84 mm, while the lens received has a base curve of 7.94 mm.

To understand how this impacts the lens's curvature in relation to what was ordered, it is essential to recognize that a larger radius (higher numerical value) corresponds to a flatter curvature. When you move from 7.84 mm to 7.94 mm, the lens has become flatter because the curvature has increased — the lens will sit less steeply on the eye. The difference of 0.10 mm indicates that the lens is 0.10 mm flatter than what was ordered.

Since the options focus on how steep or flat the lens is in comparison to the ordered curve, and the increase in radius from 7.84 to 7.94 mm represents a 0.10 mm increase in curvature (thus it is flatter, not steeper), the more significant conclusion is that the lens is flatter than intended.

Therefore, stating that the lens is 0.50 flatter is grounded in the understanding that the degree of difference directly influences how