With constant base curve, increasing diameter changes sagittal height by

With constant base curve, increasing diameter changes sagittal height by

• A. Decreases
• B. Increases
• C. Stays the same
• D. Becomes zero

Answer: (B)

Sagittal height reflects how high the lens curves away from the cornea at the periphery. When the base curve is fixed, the interior curvature radius stays the same, so extending the diameter pushes the edge farther from the center along a circular arc. For a circular arc, the height above the center increases as you move outward, since s = R − sqrt(R^2 − x^2) and, for small x, s ≈ x^2/(2R). Increasing diameter means a larger x, which increases sagitta, so the sagittal height rises. The other possibilities would require the height to stay the same, drop, or go to zero, which doesn’t happen with a larger radius of measurement on a fixed-curvature surface.

Sagittal height reflects how high the lens curves away from the cornea at the periphery. When the base curve is fixed, the interior curvature radius stays the same, so extending the diameter pushes the edge farther from the center along a circular arc. For a circular arc, the height above the center increases as you move outward, since s = R − sqrt(R^2 − x^2) and, for small x, s ≈ x^2/(2R). Increasing diameter means a larger x, which increases sagitta, so the sagittal height rises. The other possibilities would require the height to stay the same, drop, or go to zero, which doesn’t happen with a larger radius of measurement on a fixed-curvature surface.