Test Reviews Part 3 Flashcards
The concentric, aspheric and diffractive lens designs are all … lenses
Simultaneous
Prism ballast, double slab-off and peri-ballast are all what type of lens design?
a) Soft toric
b) Bifocal
c) Therapeutic
d) Spherical
a) Soft toric
In choosing the diameter of a soft lens, what is the general rule of thumb?
a) 1.00 mm larger than HVID
b) 2.00 mm. larger than HVID
c) 3.00 mm larger than HVID
d) None of the above
b) 2.00 mm. larger than HVID
Fluoro-silicone acrylate (FSA) materials contain a fluorinated monomer similar to Teflon (R) that makes them glide
more … in the eyes and shed deposits with each blink.
smoothly
high Dk RGP lenses
contain … silicone, which decreases their stability and deposit resistance
more
Given the following information: K’s 42.00 @ 180 / 42.00 @ 90 Rx -3.00 -2.00 x 180
A front surface toric RGP lens will probably be necessary to correct the patient’s residual astigmatism
Choices back-surface toric or bitoric are incorrect because there is no corneal toricity to stabilize a back surface toric or bitoric RGP lens
A patient’s K readings are 43.50 @ 180 / 41.50 @ 90. A spherical RGP lens can be expected to:
Displace down and in or down and out with each blink
This patient has against-the-rule astigmatism and the cornea has a vertical ellipsoidal shape. When an RGP lens is
placed on this type of cornea, a fulcrum or bearing point is established at 6 and 12 o’clock in the vertical meridian.
There are no bearing points in the horizontal meridian to help guide the lens in its downward excursion and the lens
will tend to decenter nasally or temporally with the blink.
Which special RGP lens design would be beneficial for this patient given the following information?
K’s 44.00 @ 180 / 46-50 @ 90
Rx -11.00 +2.50 x 90
Hyperflange
A patient is diagnostically fit with a rigid gas permeable lens with the following parameters: 42.50 -3.00 9.5.
If you wish to flatten the lens to cornea relationship, which of the following lenses would you order?
a) 42.00 -2.50 10.0
b) 42.50 -3.00 9.0
c) 43.00 -3.50 9.5
d) 43.50 -3.50 9.0
b) 42.50 -3.00 9.0
Only “B” will flatten the lens to cornea relationship because it reduces the
lens diameter without altering (steepening) the base curve.
The tolerance for the overall lens diameter according to the ANSI standards is:
b) + 0.05 mm
All of the following will enable the practitioner to verify the overall rigid gas permeable lens diameter except:
a) Slot gauge
b) Shadowgraph
c) Measuring magnifier
d) Radiuscope
d) Radiuscope
An instrument that allows simultaneous verification of lens diameter, optic zone width and peripheral curve
width is:
a) Measuring magnifier
b) Ophthalmometer
c) Profile analyzer
d) Radiuscope
a) Measuring magnifier
Another name for the keratometer
An ophthalmometer
Assessment of the quality of the peripheral curves (blends) of a rigid contact lens is achieved by the use of the:
a) Profile analyzer
b) Shadowgraph
c) Keratometer
d) Burton lamp
a) Profile analyzer
The instrument used for magnification of the edge of a rigid contact lens is a:
a) Keratometer
b) Shadowgraph
c) Profile analyzer
d) V-groove gauge
b) Shadowgraph
The tolerance for lens power under + / -10.00 D is:
0.12 D
Radiuscope
Spherical One base curve
Lensometer
Spherical Rx
Spherical
Radiuscope
Two base curves
Lensometer
Spherical Rx
Warped
Radiuscope
One base curve
Lensometer
Sphero-cylindrical Rx
Front Toric
Radiuscope
Two base curve
Lensometer
Sphero-cylindrical Rx
Back toric and bitoric
Which of the following will NOT measure contact lens parameters?
a) Keratometer
b) Radiuscope
c) Burton lamp
d) Thickness gauge
a) Keratometer
New soft lens fits should be seen one week, one month, three months and 6 months from the time of their
initial fit, then every 6 to 12 months
true
Which of the following materials would least likely require a weekly enzymatic cleaner?
a) Polymethylmethacrylate.
b) Hydrophilic
c) Hydroxyethyl Methacrylate
d) Silicone acrylate
a) Polymethylmethacrylate
all the rest are required weekly
Which type of lens would best satisfy this patient’s visual needs given the following information?
K’s 43.00 @ 160 / 44.00 @ 75 3+ distortion
Rx -2.00 + 1.00 x 75
a) Spherical soft lens
b) Soft toric lens
c) Soft bifocal lens
d) Spherical RGP lens
d) Spherical RGP lens
A rigid contact lens measures +15.00 BVP. The FVP will measure:
A lesser dioptric reading
Which of the following preservatives has a low incidence of ocular sensitivity with soft contact lenses?
Sorbic acid
Patients who are fit with lenses that will be worn overnight on a flexible or extended wear basis:
Should be seen as early as possible in the morning for follow-up of overnight wear
The base curve of a rigid lens was ordered 7.84 mm and was received measuring 7.94 mm.
This lens is ________ than ordered
0.50 D flatter
One might utilize which of the following lens designs given the following information:
K’s 46.00 @ 75 / 48.50 @ 165 +2 distortion
Rx -7.00 -3.50 x 165
Irrregular retinoscopy reflexes
Soper keratoconus design
There is a high probability that this patient has keratoconus, typified by the steep keratometer readings, the high
degree of cylinder and the irregular retinoscopy reflexes.
When verifying a rigid lens on a radiuscope, you notice that the mires are not in focus in all principle meridians.
This might indicate a:
1) Warped lens
2) Back toric lens
3) Bi-Toric lens
4) Front toric lens
1) Warped lens
2) Back toric lens
3) Bi-Toric lens
Which of the following may cause a soft lens to need to be replaced more often?
Heat disinfection
Which of the following is a preservative found in soft contact lens solutions?
a) Chlorbutanol
b) Polyquad
c) Benzalkonium chloride
d) Benzyl alcohol
b) Polyquad
Conventional daily wear soft contact lenses, properly cared for, should be replaced at least:
Yearly
Which medication should not be used with soft contact lenses as it will turn the lens brown?
a) Antacids
b) Epinephrine
c) Digitalis
d) Insulin
b) Epinephrine
The purpose of a combination wetting/soaking RGP solution is to:
a) Maintain lens surface wettability
b) Disinfect the lens
c) Cushion the lens during insertion
Enzymatic cleaning of soft lenses is important in:
a) Preventing the development of GPC
b) Preventing the lens from shrinking and tightening
c) Maintaining the hydration of the lens
Which of the following is not considered a normal adaptive response to soft lenses?
Lenses feeling “hot” in the late afternoon
Solution containers should … be capped after use to prevent contamination
always
Is effective against acanthamoeba cysts and trophozoites
Thermal disinfection of soft lenses
… is more effective against viruses and fungi than most chemical disinfection systems
Hydrogen peroxide
