Contact Lens Fitting and Evaluation, Exams of Nursing

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NCLE Practice Test Practical questions and answers new solution

NCLE Practice Test Practical questions and answers new solution Steep Fluorescein Pattern - CORRECT ANSWER Bright green pooling center, very faint green pooling on diameter of lens Flat Fluorescein Pattern - CORRECT ANSWER Bright green pooling on diameter of lens, very faint green in center Against-the-rule Astigmatism Pattern - CORRECT ANSWER Bright green pooling horizontally, faint green pooling vertically With-the-rule Astigmatism Pattern - CORRECT ANSWER Bright green pooling vertically, faint green pooling horizontally Prism Ballast - CORRECT ANSWER Common technique to stabilize lens from rotating. Added thickness will position lens inferiorly (bottom of cornea) Truncation - CORRECT ANSWER Cutting off .50mm to 1.50mm of bottom edge of lens to provide stability. Reduces diameter, making a looser fit. Double Slab-off - CORRECT ANSWER 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 - CORRECT ANSWER Hyperflange - CORRECT ANSWER Used to correct high riding minus lenses. Myoflange - CORRECT ANSWER Used to correct low riding plus lenses.

The Main Supply of Oxygen to the cornea is provided by - CORRECT ANSWER Tear Film Keratometry mires which are only clear when the wearer blinks are indicative of a - CORRECT ANSWER Steep Fit Keratometry mires which blur immediately following blink are indicative of a - CORRECT ANSWER Flat Fit A rigid contact lens shows a flourescein pattern inferiorly and superiorly beneath the lens. This is indicative of which type of astigmatism - CORRECT ANSWER With-the-rule A bi-toric rigid lens will show - CORRECT ANSWER Two base curves on the radiuscope, sphero- cylindrical rx on the lensometer The ANSI tolerance for a soft lens diameter is - CORRECT ANSWER ±0. The ANSI tolerance for a soft lens refractive power on a Rx 5.12D to 10.00D - CORRECT ANSWER ±0. The ANSI tolerance for RGP Base Curve is - CORRECT ANSWER ±0.05mm The ANSI tolerance for RGP lens diameter is - CORRECT ANSWER ±0.05mm Which instrument allows simultaneous verification of lens diameter, optic zone width, and peripheral curve - CORRECT ANSWER Radiuscope Which instrument is best to observe the blends of rigid contact lens - CORRECT ANSWER Profile Analyzer

If a toric lens rotates to the fitters left - CORRECT ANSWER Add the degrees of rotation to the prescribed axis If a toric lens rotates to the fitters right - CORRECT ANSWER Subtract (minus) the degrees of rotation to the prescribed axis Increasing the sagittal depth of a rigid lens will - CORRECT ANSWER Not change the effective power of the lens How would you stop rotation in a bifocal lens - CORRECT ANSWER Truncate the lens Change the base curve Increase prism The DK value of a lens is - CORRECT ANSWER Oxygen permeability of that material The original rigid material used in contact lens manufacturing - CORRECT ANSWER Polymethylmethacrylate (PMMA) Orthokeratology may be defined as - CORRECT ANSWER Reduction of refractive errors by corneal molding with the contact lens applications What can be used to evaluate a dry eye patient - CORRECT ANSWER Sodium Flourscein Schirmer Strips Rose Bengal An advantage of a flourocarbon lens is its - CORRECT ANSWER High DK value

When the power of a bifocal gradually changes from the central area of the lens to the periphery, it is called - CORRECT ANSWER An aspheric lens A bifocal design that utilizes a small central reading area and a distance periphery is - CORRECT ANSWER Reverese Centrad In the manufacturing process, when there is a polished front curve, a polished back curve and a diameter, it is - CORRECT ANSWER Semi-finished lens Back toric lens works with - CORRECT ANSWER High corneal toricity Single Cut aphakic contact lenses can be well suited for patients with - CORRECT ANSWER small apertures and flat corneas In bitoric lens fitting, rotation is controlled by - CORRECT ANSWER Relationship of base curve to anterior corneal cylinder The amount of prism ballast often used in ballasted lenses to prevent lens rotation - CORRECT ANSWER 1.50D of prism A aspheric PCC - CORRECT ANSWER 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 - CORRECT ANSWER d. all the above Good example of a bifocal contact lens which may rotate without vision impairment is - CORRECT ANSWER An aspheric lens In aspheric lens design, the change in curvature that occurs from the center to the edge of the aspheric zone is - CORRECT ANSWER Eccentricity What is the easiest in-office modification to perform on RGPs? - CORRECT ANSWER Adding minus power When rigid lenses are manufactured, which parameter is cut first? - CORRECT ANSWER Central Posterior Curve/CPC/Base Curve Removal of plastic from the bottom of a lens to produce a flat edge that will control rotation - CORRECT ANSWER Truncation Mounting the lens blank in the lathe so that the face of the button is perpendicular to the spindle is necessary to avoid - CORRECT ANSWER Unwanted prism "Haptic" lens is used in reference to - CORRECT ANSWER Scleral lens A finished contact lens will have the following properties - CORRECT ANSWER 1. Diameter cut to size both sides surfaced

2. Peripheral curves have been added

c. 3mm d. 1mm - CORRECT ANSWER a. 4mm The keratometer measure a point within the cornea called the - CORRECT ANSWER Visual center The major drawback of contact lens materials containing silicone is - CORRECT ANSWER 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. - CORRECT ANSWER a. widen peripheral curves Patients should clean lenses with a surfactant cleaner - CORRECT ANSWER 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 - CORRECT ANSWER 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 - CORRECT ANSWER C. Benzylkonium chloride What is the abbreviation for fluorescein? - CORRECT ANSWER 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 - CORRECT ANSWER b. Fluorosoft The material safety data sheets (MSDS) - CORRECT ANSWER 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 - CORRECT ANSWER b. 4hrs Small superficial linear stains are characteristic of - CORRECT ANSWER Foreign particles under the lens

The deposit most often seen on extended wear lenses are: a. protein b. lipids c. calcium d. jelly bumps - CORRECT ANSWER a. proteins In the Dyer nomogram, the primary curve is the - CORRECT ANSWER 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 - CORRECT ANSWER a. dry spots Dellen - CORRECT ANSWER Localized area of corneal drying and evaporation Single-cut aphakic lens is best suited for - CORRECT ANSWER 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 - CORRECT ANSWER True HEMA is an abbreviation commonly used to describe: a) rigid lenses b) gas permeable lenses c) soft lenses d) corneal abrasion - CORRECT ANSWER c. soft lenses Rx: -4.00+1.00X K: 42.50@180/43.50@ A rigid contact lens fit "on K" would require the following power: a. -2. b. -3. c. -4. d. -5.00 - CORRECT ANSWER b. -3. the power in the lacrimal lens in the previous question is: a. plano b. +0. c. -0. d. none of these - CORRECT ANSWER a. plano

Keratometry mires which blur immediately following a blink is indicative of a: - CORRECT ANSWER a flat fit The ANSI tolerance for RGP lens diameter is: - CORRECT ANSWER +/- 0.05mm The ANSI tolerance for a soft lens diameter is: - CORRECT ANSWER +/- 0.25mm When fitting a soft lens to a patient with corneal astigmatism a _____ lens masks more of the astigmatism - CORRECT ANSWER larger This can be used to evaluate RGP lens fit instead of flourescein staining - CORRECT ANSWER Rose Bengal In an RGP lens, a poorly finished transitional zone between the optic zone and the lens edge can be evaluated by: - CORRECT ANSWER Profile Analyzer The following soft lens is placed on a patient's eye: 8.8 -4.00 14. An over-refraction is performed resulting in -0.75D. What should be ordered? - CORRECT ANSWER 8. -4.75 14. A single cut aphakic lens is best suited for patients with ______ apertures and ______corneas. a. small / flat b. small / steep c. large / flat d. large / steep - CORRECT ANSWER a. small / flat

Where is the power curve on a spin-cast soft lens? - CORRECT ANSWER The back surface Which of the following preservatives has a low incidence of ocular sensitivity with soft contact lenses? a. sorbic acid b. Chlorbutanol c. Benzalkonium Chloride d. Thimerosal - CORRECT ANSWER a. sorbic acid Thermal disinfection of soft lenses is: a. Extends the life of contacts since it kills micro organisms better than chemicals b. Can be done by boiling the lens case in a pot of water for one hour if a thermal disinfection unit is not available c. Is effective against acanthamoeba cysts and trophozoites d. Takes a minimum of two hours to decompose into water and oxygen - CORRECT ANSWER c. Is effective against acanthamoeba cysts and trophozoites Newly fitted extended wear patients should have their first recheck in - CORRECT ANSWER 24 hours If an adapted contact lens wearer complains of sudden onset of discomfort the technician should suspect - CORRECT ANSWER a damaged contact lens According to the FDA, disposable contact lenses that are removed nightly, should be discarded after: - CORRECT ANSWER 1 month