Truncation as a method for toric lenses is true because it limits rotation by what action?

Truncation as a method for toric lenses is true because it limits rotation by what action?

• A. It increases rotation
• B. It limits rotation by sitting on the lower eyelid
• C. It has no effect on rotation
• D. It applies only to rigid lenses

Answer: (B)

Truncation stabilizes a toric lens by creating a physical stop that engages with the lower eyelid. The truncated edge sits against or beneath the lower lid so that eyelid pressure during blinking prevents the lens from rotating around its optical axis. This lid–lens interaction consistently positions the lens, keeping the toric axis aligned and reducing unwanted rotation. In other words, the lower lid’s contact with the truncated edge acts as a mechanical restraint, maintaining orientation and improving visual stability.

Truncation stabilizes a toric lens by creating a physical stop that engages with the lower eyelid. The truncated edge sits against or beneath the lower lid so that eyelid pressure during blinking prevents the lens from rotating around its optical axis. This lid–lens interaction consistently positions the lens, keeping the toric axis aligned and reducing unwanted rotation. In other words, the lower lid’s contact with the truncated edge acts as a mechanical restraint, maintaining orientation and improving visual stability.