ABO Contact Lenses 3

Question 1

Which contact lens solution component is most associated with Acanthamoeba keratitis when patients use homemade saline or tap water?

Accepted Answer

Sodium chloride contaminated with Acanthamoeba cysts

Answer

Tap water and homemade saline may harbor Acanthamoeba cysts; contact of lenses or cases with these sources is the primary risk factor for Acanthamoeba keratitis.

Question 2

When evaluating a fluorescein pattern for an RGP lens fit, a 'with-the-rule' corneal astigmat fitted with a spherical RGP will show:

Accepted Answer

Bearing centrally and pooling superiorly/inferiorly

Answer

In with-the-rule astigmatism, the vertical meridian is steeper; a spherical lens bears centrally along the flat horizontal meridian and shows pooling (fluorescein) along the steep vertical meridian.

Question 3

A patient's keratometry readings are 44.00/47.00 @ 090. What type of corneal astigmatism is present?

Accepted Answer

With-the-rule astigmatism

Answer

With-the-rule astigmatism means the vertical meridian (90°) is steeper; here 47.00 D at 090 confirms the steeper vertical meridian.

Question 4

Orthokeratology (ortho-K) lenses are fitted to achieve what primary effect?

Accepted Answer

Temporarily flatten the cornea to reduce myopia

Answer

Orthokeratology uses reverse-geometry RGP lenses worn overnight to temporarily reshape (flatten) the central cornea, reducing myopia for daytime clear vision without spectacles.

Question 5

What is the recommended maximum time a conventional soft contact lens patient case should go before replacement?

Accepted Answer

3 months

Answer

Contact lens cases should be replaced every 3 months (or sooner if damaged) to reduce biofilm accumulation and contamination risk.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO Contact Lenses 3