When a flat GP lens is judged to be too flat, how should the outer optic diameter (OAD) be adjusted?

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Prepare for the Gas Permeable Contact Lenses Test. Study with flashcards and practice multiple choice questions. Each question includes hints and explanations. Ace your exam!

Multiple Choice

When a flat GP lens is judged to be too flat, how should the outer optic diameter (OAD) be adjusted?

Explanation:
A flat GP lens often sits high on the cornea with insufficient peripheral alignment, so the edge lacks stable engagement. Increasing the outer optic diameter enlarges the contact area around the eye, letting the edge sit on a more stable scleral region and improving centration and lid interaction. This reduces excessive movement and center-to-edge mismatch that come from a lens that’s too flat. Making the diameter smaller would worsen edge engagement and stability, so the best adjustment is to use a larger diameter.

A flat GP lens often sits high on the cornea with insufficient peripheral alignment, so the edge lacks stable engagement. Increasing the outer optic diameter enlarges the contact area around the eye, letting the edge sit on a more stable scleral region and improving centration and lid interaction. This reduces excessive movement and center-to-edge mismatch that come from a lens that’s too flat. Making the diameter smaller would worsen edge engagement and stability, so the best adjustment is to use a larger diameter.

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