AOA Contact Lens Practice

Question 1

Which contact lens material parameter describes the amount of oxygen that actually reaches the cornea?

Accepted Answer

Dk/t (oxygen transmissibility)

Answer

Dk/t (oxygen transmissibility) is the measure of oxygen flux through a specific lens thickness and determines how much oxygen reaches the corneal epithelium.

Question 2

Extended wear contact lenses are most associated with which serious complication?

Accepted Answer

Microbial keratitis

Answer

Extended (overnight) wear dramatically increases the risk of microbial keratitis, particularly from Pseudomonas aeruginosa and Acanthamoeba.

Question 3

Orthokeratology (ortho-K) lenses work primarily by:

Accepted Answer

Reshaping the corneal epithelium during overnight wear

Answer

Ortho-K uses reverse geometry RGP lenses worn overnight to temporarily flatten the central corneal epithelium, reducing myopia during the day.

Question 4

Giant papillary conjunctivitis (GPC) in contact lens wearers is best managed by:

Accepted Answer

Switching to daily disposable lenses and reducing wear time

Answer

GPC is an immunological response to lens deposits and mechanical trauma; daily disposables eliminate deposit accumulation and reduce antigenic load.

Question 5

Which fitting relationship describes a rigid gas-permeable (RGP) lens that is steeper than the corneal curvature?

Accepted Answer

Steep (vaulting) fit

Answer

When a RGP lens base curve is steeper than the flattest corneal meridian (K), the lens vaults the cornea and causes apical clearance.

AOA - American Optometric Association Practice Test

AOA - American Optometric Association Practice Test

AOA Contact Lens Practice