The first successful contact lenses which were originally molded to conform to the
shape of the cornea were known as - ANS Scleral/Haptic lenses
Corneal contact lenses: - ANS are the most common design for rigid and gas
permeable lenses.
The majority of soft lenses fit today are: - ANS semi-scleral
A liquid coming in contact with a hydrophilic lens material with a relatively small wetting
angle would be likely to: - ANS spread evenly over its surface
A contact lens with diameter larger than that of the cornea is called - ANS Scleral/haptic
lens
All of the following are symptoms of a loose fitting lens except: - ANS burning
Of those curves listed, which indicates the flattest base curve? - ANS 37.50 diopters
A contact lens was ordered with a base curve of 7.85 mm but was received back from
the laboratory with a base curve measuring 7.80 mm. The base curve of the actual lens
is: - ANS 0.25 D steeper than the lens ordered
It is noticed that a rigid contact lens containing a base curve of 7.42 mm is fitting quite
loose. A tighter fit may be achieved by changing the base curve to: - ANS Reduce to
tighten bc
A contact lens has a base curve of 7,50 mm, Its posterior peripheral curve would most
likely be: - ANS 42.50 D
The secondary curve of a rigid contact lens is generally: - ANS 2 to 4 diopters flatter
than the CPC
The term "Haptic Lens" is used in reference to: - ANS scleral lens
The CPC of a contact lens measures 7.5 mm radius of curvature. Its power in diopters
is: - ANS 45.00 D
, The fitting characteristics of a gas permeable rigid contact lens may be altered by: -
ANS changing the radius of curvature of the CPC, increasing the diameter, & widening
the PPC
A soft contact lens demonstrates excessive movement. This may be remedied by: -
ANS a larger diameter tightens lens
The term "sagittal value" refers to: - ANS the vaulting effect of a contact lens
When determining the best lens material to use, which of the following should be
considered? - ANS the patient's working conditions, precorneal tear film evaluation, &
full time vs part time wear
The gas permeability of a CAB lens is largely dependent upon: - ANS the lens thickness
A rigid gas permeable lens with a base curve of 7,50 mm is found to be fitting slightly
tight. To improve the fit we might consider changing the base curve to which of the
following? - ANS 7.55 flatten by increase bc
If the CPC of a rigid contact lens is held constant while the diameter is increased, it
would result in: - ANS a tighter fit
When compared with PMMA, CAB lenses: - ANS have much better gas permeability
can be fit larger are less likely to result in hypoxia induced corneal edema
When compared with PMMA which of the following is not true about CAB lenses? - ANS
they have excellent shape retention
HEMA is an abbreviation commonly used to describe: - ANS soft lenses
The chief reason to utilize a ballasted contact lens is: - ANS to inhibit lens rotation
Which of the following is not true of PMMA lenses? - ANS they have excellent gas
permeability
Which of the following is not true about soft contact lenses? - ANS spherical lenses will
correct for moderate to high amounts of corneal astigmatism
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