NCLE Prep Flashcards
(26 cards)
The tolerance for a rigid lens power under +/- 5.00
0.12
The tolerance for the overall lens diameter according to the ANSI standards is
+/- 0.05
The average pH value of the human tear is
7.4
If the manufacturer’s guidelines suggest a minimum of 4 hours for disinfection, what would you suggest to the patient?
minimum of 4 hours required
The cornea has five distinct layers. In order from anterior to posterior they are:
Epithelium, Bowman’s layer, Stroma, Descemet’s membrane, Endothelium
A normal tear break-up time is:
10-12 seconds
A whitish haze in the peripheral corneal stroma which does not stain and is often seen in the elderly is know as:
Arcus Senilus
Patients with keratitis sicca are more prone to?
secondary infections
The average life span of corneal epithelial cell from mitosis through maturation and desquamation most nearly approximates?
1 week
In a Schirmer I test
A patient with an unanesthetized eye and normal tear output should wet at least 15 mm of the filter paper in 5 minutes
The preservative in contact lens solutions
Is formulated to keep microorganisms from multiplying in a bottle of contact lens solutions after it has been opened
The average HVID for a patient is
11.5
To aid in the positioning of a GP prism ballast lens riding too low and slipping underneath the lower lid which of the following might be helpful?
truncation
In prescriptions of 4.00 D or greater, fitting contact lenses requires compensating the power for the change in vertex distance. When moving from the spectacle plane to the corneal plane, the compensated power will be?
more plus
A prism ballast GP lens requires how much prism for proper orientation?
0.75 to 1.50D
The longer the radius of curvature of a contact lens?
flatter the lens
Up until the recent introduction of silicone hydrogel lenses the Dk/t of previous hydrogel lenses was limited by
Water content and center thickness
Fitting soft lenses steeper than K will usually result in
Fluctuations in vision following the blink
A bifocal lens in which the power gradually changes from the central area of the lens to a periphery is known as
an aspheric lens
How many diopters of power will bring parallel rays of incident light to focus at a distance of one meter?
one diopter
In which of the following types of corneal astigmatism is a GP lens most indicated?
irregular
Spherical equivalent powers position which of the following on the retina?
Circle of least confusion
Keratoconus and penetrating keratoplasty fittings are best accomplished by which of the following methods?
diagnostic fitting
The following ametropia frequently results in high riding rigid lenses
high myopia
