AOA Contact Lens Practice 2

Question 1

Scleral contact lenses differ from corneal RGP lenses primarily because they:

Accepted Answer

Vault the entire cornea and rest on the sclera

Answer

Scleral lenses have a large diameter (>18 mm) that vaults the cornea completely and lands on the scleral tissue, holding a fluid reservoir over the cornea.

Question 2

Silicone hydrogel lenses have largely replaced conventional hydrogel lenses because they offer:

Accepted Answer

Higher oxygen permeability with similar or better comfort

Answer

Silicone hydrogel materials achieve Dk values 5–6× higher than conventional hydrogels, reducing hypoxic complications while maintaining wearable comfort.

Question 3

Acanthamoeba keratitis is uniquely associated with which contact lens behavior?

Accepted Answer

Rinsing lenses with tap water or swimming while wearing lenses

Answer

Acanthamoeba is a waterborne protozoan; exposure through tap water rinsing or water sports creates the primary risk for this difficult-to-treat corneal infection.

Question 4

When fitting toric soft contact lenses, the lens should rotate to the:

Accepted Answer

Correct orientation as marked by the stabilization ballast

Answer

Toric lenses use prism ballast or peri-ballast stabilization to maintain axis orientation; correct on-eye position is verified by the lens markings aligning with the intended axis.

Question 5

Which condition is a primary indication for fitting a patient with rigid gas-permeable lenses instead of soft lenses?

Accepted Answer

Keratoconus with irregular astigmatism

Answer

RGP lenses mask irregular corneal surface and provide superior optical quality for keratoconus patients, unlike soft lenses that drape the irregular surface.

AOA - American Optometric Association Practice Test

AOA - American Optometric Association Practice Test

AOA Contact Lens Practice 2