The diameter often causes the lens to displace in which direction?

• A. temporally
• B. nasally
• C. superiorly
• D. inferiorly

Answer: (A)

When a soft contact lens’s diameter isn’t matched well to the corneal size, the edge of the lens isn’t properly centered over the cornea. The eyelids’ blink action tends to sweep tear film and the lens edge toward the temporal side. With an improper diameter, the lens has less stable, even support around the nasal rim and is more easily nudged outward toward the temporal side as the lids move. In practice this means the lens tends to shift toward the temple during wear, rather than staying centered or moving in other directions. So, the diameter issue most often shows up as temporal displacement.