NOCE Contact Lens Fitting and Dispensing 2

Question 1

During an RGP lens follow-up, a lens rides superiorly and shows temporal lag with each blink. What is the most likely cause?

Accepted Answer

The lens is fitted too flat

Answer

A flat-fitting RGP lens has poor corneal alignment, causing it to decenter superiorly and exhibit excessive movement and temporal lag on the blink.

Question 2

What is the purpose of performing an 'over-refraction' during a contact lens fitting?

Accepted Answer

To refine the contact lens power while the lens is on the eye

Answer

Over-refraction is performed with the trial contact lens in situ to determine what additional power is needed to achieve best corrected acuity with that specific lens.

Question 3

A soft lens patient reports significant end-of-day dryness and discomfort. Which change would MOST likely improve comfort?

Accepted Answer

Switching to a silicone hydrogel lens material

Answer

Silicone hydrogel lenses provide higher oxygen transmissibility and tend to maintain better surface wettability throughout the day, reducing end-of-day dryness compared to conventional hydrogels.

Question 4

What does 'limbal clearance' refer to in the context of contact lens fitting?

Accepted Answer

The space between the lens edge and the corneal limbus

Answer

Limbal clearance is the space between the edge of a contact lens and the corneal limbus (corneoscleral junction), which is important for limbal vessel health and comfort.

Question 5

For a patient with a spectacle prescription of -2.50 -1.50 x 180, which contact lens type would provide BEST visual correction?

Accepted Answer

Toric soft contact lens

Answer

With 1.50 D of cylinder, a toric soft lens is the most appropriate choice since the residual astigmatism with a spherical lens would likely reduce visual acuity significantly.

NOCE - National Opticianry Competency Examination Practice Test

NOCE - National Opticianry Competency Examination Practice Test

NOCE Contact Lens Fitting and Dispensing 2