Test Reviews Part 4 Flashcards
Which of the following can NOT be used to measure the diameter of a rigid lens?
a) Profile analyzer
b) Measuring magnifier
c) Diameter gauge
d) Shadowgraph
a) Profile analyzer
Use of a Wratten # 12 or Tiffen yellow filter is important in evaluating the fluorescein pattern of patients with
RGP lenses because:
Many patients are wearing lenses containing UV inhibitors that block fluorescein
If fluorescein evaluation reveals apical staining, it could be due to:
a) A lens that is too flat and loose
b) A lens that is too steep and tight
c) Corneal edema
d) All of the above
d) All of the above
If an RGP lens fails to provide acceptable visual acuity, the fitter should first
Have a sphero-cylindrical over-refraction performed to see if the reduced acuity is due to residual astigmatism
According to the FDA, disposable contact lenses that are removed nightly, should be discarded after
2 weeks
Circumcorneal. injection in a soft lens wearer may be a sign of:
a) Tight lens syndrome
b) Solution sensitivity
c) Keratitis
A technician can perform a preliminary evaluation of soft contact lens movement by:
a) Observing the movement of the lens edge in relation to the position of a conjunctival vessel
b) Having the patient look up and blink
c) Observing movement and lens lag in upward and lateral gaze with a penlight
Which of the following statements concerning lens movement is not correct:
a) A tight lens may cause blanching of the limbal vessel
b) A tight lens may cause scleral indentation
c) A loose lens may cause blurred vision immediately following the blink
d) A loose lens will be considerably more comfortable than a tight lens
The answer is D
Which of the following modifications to a rigid gas permeable lens can not be made in the office?
a) Blending of peripheral curves
b) Addition of minus power
c) Polishing lens surface
d) Changing the base curve
d) Changing the base curve
- In-office polishing of the anterior surface of a rigid gas permeable lens surface will provide many benefits to the
patient. Which of the following is not a benefit of polishing the lens in the office?
a) Cleaner lens surface
b) Increased lens comfort
c) Thinner lens edge
d) Removal of scratches on the lens surface
c) thinner lens edge
What is the most important feature of an in-office modification unit?
Variable speed motor
The “watermelon seed” principle relies on the pressure of the upper lids to maintain the correct orientation of a prism
ballasted toric lens and keep it from rotating off axis. In an exophthalmic eye, the retracted lids are unable to grasp the
edge of the lens to maintain its orientation. The lens will generally not be expelled forcibly but may dehydrate, shrink
and fall out spontaneously.
If a patient with exophthalmic eyes due to thyroid disease requires a toric lens
Which of the following is not characteristic of corneal edema?
a) Smoky vision
b) Spectacle blur
c) Increase in K readings
d) Peripheral flare
d) peripheral flare
Which is used when blending peripheral curves in the office?
Radius tools
Polishing compound
Suction cups or a spinner tool
not the slot gauge
When keratometric mires reflected off a soft contact lens are only clear when the wearer blinks, the lens fit is
too:
a) Small
b) Large
c) Steep
d) Flat
c) steep
Gross corneal edema, which manifests itself clinically as central corneal haze, is verified by the slit lamp using
sclerotic scatter illumination. What specific technique does the examiner use to see this condition?
The naked eye and an angle between the slit lamp beam and the eye of 90 degrees
When inspecting the blend on the bevel of an RGP lens, An ideal blend should show a …
J-shaped or ski pattern in a smooth curve
Diffuse central punctate staining is an indication of:
tight lens
Sandy returns to your office after being fit with soft contact lenses. She has complaints of the lenses becoming
uncomfortable and burning as the day progresses. What might be the reason?
The lens is too tight
With a rigid contact lens in place, a fluorescein pattern shows a concentration of fluorescein inferiorly and
superiorly beneath the lens. Which one of the following types of astigmatism is represented by this pattern?
With-the-rule astigmatism
Fluorescein will be absent or minimal where the cornea is flatter and pool or collect where the cornea is steeper
true
check 164
164
Corneal edema is observed inferiorly under a prism ballast toric soft lens. What is the probable cause?
Prism thickness is too great this lens
A soft lens has edge lift when observed on a cornea. How can this be corrected?
Steepen the base curve
In evaluating a soft lens with either keratometry mires or retinoscopic reflex, you detect distortion immediately
after the blink followed by clear mires. This is caused by
A flat fitting lens
FDA Group … lenses have a negatively charged surface that attracts positively charged tear film, proteins and
lipids
IV
Which type of slit lamp illumination is used for observing tear break up time?
Diffuse illumination
A non-wetting rigid gas permeable lens may cause:
Hazy, filmy vision
Lens awareness
Dryness or grittiness
1) Pressure exerted by the upper lid
2) High Dk Lens material
3) Apical clearance lens design
4) Against the rule corneal toricity
Causes of lens flexure may include
When evaluating fluorescein patterns, a special filter must be used with:
Polymers with a UV blocker
Which of the following could cause a patient’s rigid contact lens to displace frequently and pop out without
cause?
Excessive posterior peripheral curve
Flat base curve relationship
Among the following choices, which is the latest lens design for keratoconus?
Rose K design
A soft contact lens that is too loose may show all of the following EXCEPT:
Limbal compression
A patient with a high degree of with-the-rule astigmatism fitted with a spherical rigid gas permeable lens will
show touch
On the horizontal meridian
A rigid lens showing apical touch is an indication of:
A flat fit
A rigid lens showing excessive apical pooling is an indication of
A steep fit
Contact lenses that have a non-spherical back surface are called
Aspheric lenses
A rigid lens showing central vaulting is indicative of:
Apical clearance fit
A rigid lens showing a band-shaped area of touch on the flattest meridian is an indication of
An astigmatic fit
When there is a slight pooling of fluorescein in the peripheral curve portion of a rigid lens, it indicates:
slight edge lift
