NCLE Practice Test Practical

Steep Fluorescein Pattern

Bright green pooling center, very faint green pooling on diameter of lens

Flat Fluorescein Pattern

Bright green pooling on diameter of lens, very faint green in center

Against-the-rule Astigmatism Pattern

Bright green pooling horizontally, faint green pooling vertically

With-the-rule Astigmatism Pattern

Bright green pooling vertically, faint green pooling horizontally

Prism Ballast

Common technique to stabilize lens from rotating. Added thickness will position lens inferiorly (bottom of cornea)

Truncation

Cutting off .50mm to 1.50mm of bottom edge of lens to provide stability. Reduces diameter, making a looser fit.

Double Slab-off

Lens is thicker centrally and thinner at top and bottom of lens. Provides comfort to wearer, but may cause some stability issues.

Aspheric Lens Design

Hyperflange

Used to correct high riding minus lenses.

Myoflange

Used to correct low riding plus lenses.

Monovision

Corrects presbyopia in contact wearers. One eye uses distance (dominant) and the other eye uses reading (resessive)

Segment Bifocal

Same concept as spectacle bifocal. Must be prism ballast. Often crescent shaped.

Toric Lenses

Anterior (front surface), back spherical surface or posterior (back surface), toric back curve

Front Toric Lens

Corrects a low to moderate amount of corneal astigmatism

Back Toric Lens

Corrects a mid to high amount of corneal astigmatism

Bitoric Lens

Corrects 1.50D of corneal astigmatism and high residual astigmatism

Aphakic

Condition of no crystalline lens

Psuedophakic

Implant, intraocular lens

Corneal Edema

Always causes a poor fitting lens

Spectacle Blur

Temporary blurred vision upon switching from contact lenses to eyeglasses

Crystalline Lens

The main focusing mechanism of the eye

The Main Supply of Oxygen to the cornea is provided by

Tear Film

Keratometry mires which are only clear when the wearer blinks are indicative of a

Steep Fit

Keratometry mires which blur immediately following blink are indicative of a

Flat Fit

A rigid contact lens shows a flourescein pattern inferiorly and superiorly beneath the lens. This is indicative of which type of astigmatism

With-the-rule

A bi-toric rigid lens will show

Two base curves on the radiuscope, sphero-cylindrical rx on the lensometer

The ANSI tolerance for a soft lens diameter is

±0.25

The ANSI tolerance for a soft lens refractive power on a Rx 5.12D to 10.00D

±0.18

The ANSI tolerance for RGP Base Curve is

±0.05mm

The ANSI tolerance for RGP lens diameter is

±0.05mm

Which instrument allows simultaneous verification of lens diameter, optic zone width, and peripheral curve

Radiuscope

Which instrument is best to observe the blends of rigid contact lens

Profile Analyzer

If a toric lens rotates to the fitters left

Add the degrees of rotation to the prescribed axis

If a toric lens rotates to the fitters right

Subtract (minus) the degrees of rotation to the prescribed axis

Increasing the sagittal depth of a rigid lens will

Not change the effective power of the lens

How would you stop rotation in a bifocal lens

Truncate the lens

Change the base curve

Increase prism

The DK value of a lens is

Oxygen permeability of that material

The original rigid material used in contact lens manufacturing

Polymethylmethacrylate (PMMA)

Orthokeratology may be defined as

Reduction of refractive errors by corneal molding with the contact lens applications

What can be used to evaluate a dry eye patient

Sodium Flourscein

Schirmer Strips

Rose Bengal

An advantage of a flourocarbon lens is its

High DK value

Given an Rx of -4.00 + 0.75 x 90 K readings of 43.50@180/44.25@90 a lens designed on K would have an effective sphere power of

-3.25 (always remember to transpose to minus format)

A protein found in the tear film that is a potent germ killer

Lysozyme

When trial lens fitting a soft lens patient, after placing the lens on the eye, you should

Allow the lens to settle twenty minutes before evaluating

Corneal epithelial edema will appear as

A grey haze, using a slit lamp with sclerotic scatter and the unaided eye

Apical flourescein pooling under a rigid lens indicates

A tight fit

A dynamic flourescein pattern is best illuminated by

Cobalt blue light

An "ideal" flouorescein pattern for a spherical lens on a spherical cornea would show

An even distribution of flourescein with added thickness under the peripheral curves

When a rigid contact lens shows apical touch, this would indicate

A flat fit

When a spectacle Rx exceeds __________ D, vertex distance must be compensated for when determining the power of a contact lens

±4.00

Astigmatism that is left over after a contact lens is placed on the eye

Residual Astigmatism

Fenestrations are put into a lens to

Increase oxygen transmission

When the power of a bifocal gradually changes from the central area of the lens to the periphery, it is called

An aspheric lens

A bifocal design that utilizes a small central reading area and a distance periphery is

Reverese Centrad

In the manufacturing process, when there is a polished front curve, a polished back curve and a diameter, it is

Semi-finished lens

Back toric lens works with

High corneal toricity

Single Cut aphakic contact lenses can be well suited for patients with

small apertures and flat corneas

In bitoric lens fitting, rotation is controlled by

Relationship of base curve to anterior corneal cylinder

The amount of prism ballast often used in ballasted lenses to prevent lens rotation

1.50D of prism

A aspheric PCC

Is a toric pcc and has a specific eccentricity value

Diameter of a contact lens can be reduced by:

a. razor blade

b. cut down stone

c. file technique

d. all the above

d. all the above

Good example of a bifocal contact lens which may rotate without vision impairment is

An aspheric lens

In aspheric lens design, the change in curvature that occurs from the center to the edge of the aspheric zone is

Eccentricity

What is the easiest in-office modification to perform on RGPs?

Adding minus power

When rigid lenses are manufactured, which parameter is cut first?

Central Posterior Curve/CPC/Base Curve

Removal of plastic from the bottom of a lens to produce a flat edge that will control rotation

Truncation

Mounting the lens blank in the lathe so that the face of the button is perpendicular to the spindle is necessary to avoid

Unwanted prism

"Haptic" lens is used in reference to

Scleral lens

A finished contact lens will have the following properties

1. Diameter cut to size both sides surfaced

2. Peripheral curves have been added

3. Edge has been finished.

What contact lens offers the best comfort and easiest adaptation?

Soft

Which of the following has the flattest curve?

a. 7.50mm

b. 7.90mm

c. 8.10mm

d. 7.20mm

c. 8.10mm

Which of the following has the steepest curve?

a. 43.00D

b. 47.50D

c. 49.00D

d. 39.00D

C. 49.00D

The rate at which oxygen passes through a specific contact lens of a given thickness

Oxygen transmissibility

At a 36.00D curve on the keratometer measures approximately ____mm chord of the cornea.

a. 4mm

b. 8mm

c. 3mm

d. 1mm

a. 4mm

The keratometer measure a point within the cornea called the

Visual center

The major drawback of contact lens materials containing silicone is

Wettability

Which of the following parameter changes can be made to the original lens?

a. widen peripheral curves

b. change CPC

c. make POZ larger

d. change C.T.

a. widen peripheral curves

Patients should clean lenses with a surfactant cleaner

After removal

When keratometric mires reflected off a soft lens are only clear when the wearer blinks, the lens fit is too:

a. small

b. large

c. tight

d. loose

C. Tight

What preservative, found in gas perm solutions, can cause serious problems for uses of soft contact lenses?

a. Dymed

b. Thimersoal

c. Benzylkonium chloride

d. Sodium borate

C. Benzylkonium chloride

What is the abbreviation for fluorescein?

NaFl

What type of dye can be used with soft lenses that have less than 55% water content?

a. Fluorescein

b. Fluorosoft

c. Rose Bengal

d. none of thsese

b. Fluorosoft

The material safety data sheets (MSDS)

List procedures to be followed in the event of contact with potentially harmful chemicals

RGP lenses should soak for a minimum of _____ hours for disinfection to take place.

a. 6hrs

b. 4hrs

c. overnight

d. no soaking is needed

b. 4hrs

Small superficial linear stains are characteristic of

Foreign particles under the lens

DK/L stands for

Oxygen Transmissibility

Diffuse corneal stippling obsered during a routine 6 month follow-up visit is most like due to

Posterior surface deposits

Fluorescein patter which shows a touch of apperance in the horizontal meridian and a bright green in the vertical indicates

With the rule astigmatism

An RGP is found to flex on the eye, which lens mods are available to the fitter?

a. larger diameter

b. steeper base curve

c. flatten base curve

d. thicker lens

e. c and d

e. c and d

Flatten base curve and thicker lens

When modifying RGP lenses

a. fast spindle is necessary

b. an ammonia-based polishing compound should be used

c. the polishing compound should be frequently applied

d. modifications should be avoided

c. the polishing compound should be frequently applied

The deposit most often seen on extended wear lenses are:

a. protein

b. lipids

c. calcium

d. jelly bumps

a. proteins

In the Dyer nomogram, the primary curve is the

The flattest K

Under slit lamp evaluation with fluorescein, corneal areas that appear dark and do not hold stain during blinking are most likely

a. dry spots

b. punctuates

c. infiltrates

d. abrasions

a. dry spots

Dellen

Localized area of corneal drying and evaporation

Single-cut aphakic lens is best suited for

Steep corneas (over 45.00D), and small palpebral apertures

For every 1.00D step, there's approximately 0.20mm change in diameter.

True

or

False

True

HEMA is an abbreviation commonly used to describe:

a) rigid lenses

b) gas permeable lenses

c) soft lenses

d) corneal abrasion

c. soft lenses

Rx: -4.00+1.00X90

K: 42.50@180/43.50@90

A rigid contact lens fit "on K" would require the following power:

a. -2.00

b. -3.00

c. -4.00

d. -5.00

b. -3.00

the power in the lacrimal lens in the previous question is:

a. plano

b. +0.50

c. -0.50

d. none of these

a. plano

The primary source of oxygen for the cornea is

tears