Contact Lens Fitting and Care Flashcards

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

Answer: Dk/t (oxygen transmissibility)

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.

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

Answer: Rigid gas permeable (RGP) lens

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

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

Answer: 6 hours

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

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

Answer: Patients with severe dry eye disease or irregular corneas

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.

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?

Answer: Vertex distance compensation

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.

A patient develops a red, painful eye with a corneal infiltrate after sleeping in monthly replacement soft contact lenses. What is the most likely diagnosis?

Answer: Microbial keratitis

Microbial keratitis is a serious corneal infection associated with overnight contact lens wear and presents with pain, redness, and a corneal infiltrate.