NOCE Contact Lens Fitting and Care 3

Question 1

Which parameter describes how well a contact lens material allows oxygen to pass through to the cornea?

Accepted Answer

Dk/t (oxygen transmissibility)

Answer

Dk/t, or oxygen transmissibility, accounts for both the material's oxygen permeability (Dk) and the lens thickness (t) to determine actual oxygen delivery to the cornea.

Question 2

A keratoconus patient is best managed with which type of contact lens to achieve optimal visual acuity?

Accepted Answer

Rigid gas permeable (RGP) lens

Answer

RGP lenses mask the irregular corneal surface of keratoconus by providing a smooth tear lens interface, significantly improving visual acuity.

Question 3

What is the ANSI recommended minimum time for neutralization when using a two-step hydrogen peroxide contact lens disinfection system?

Accepted Answer

6 hours

Answer

A minimum of 6 hours is required for complete neutralization of hydrogen peroxide to prevent ocular damage when inserting lenses.

Question 4

Which segment of patients would most benefit from scleral contact lenses?

Accepted Answer

Patients with severe dry eye disease or irregular corneas

Answer

Scleral lenses vault completely over the cornea and rest on the sclera, providing a fluid reservoir that relieves severe dry eye and corrects irregular corneas.

Question 5

When converting a spectacle prescription of −3.00 DS to a contact lens power, which factor must be considered for prescriptions exceeding ±4.00 D?

Accepted Answer

Vertex distance compensation

Answer

For prescriptions above ±4.00 D, the vertex distance must be accounted for when converting spectacle power to contact lens power, as the lens sits on the cornea.

NOCE - National Opticianry Competency Examination Practice Test

NOCE - National Opticianry Competency Examination Practice Test

NOCE Contact Lens Fitting and Care 3