NAO BOOK + TEST REVIEW BOOK
QUESTIONS AND ANSWERS
The first successful contact lens were molded to the shape of the cornea known as:
Corneal
Hapatic
Interpalpebral
Gas Permeable - Correct Answers -Hapatic
Corneal Contact lenses:
Are a typical soft contact lens design
Bridge the limbus and some of the sclera
Are last resort contact lenses
Are common designs for rigid and gas perm contacts - Correct Answers -Are common
designs for rigid and gas perm contacts
The majority of soft lenses fit today are:
Corneal
Hapatic
Semi scleral
Hydrophobic - Correct Answers -Semi scleral
A liquid coming in contact with a hydrophilic lens material with a relatively small wetting
angle would be likely to:
Form beads on the surface
Quickly evaporate
Spread evenly over the surface
None of the above - Correct Answers -Spread evenly over the surface
A contact lens with a diameter larger than that of the cornea is called a ____ lens.
Corneal
Hydrophilic
Hydrophobic
Hapatic - Correct Answers -Hapatic
All of the following are symptoms of a loose fitting lens except:
Constant awareness
,Lid sensation
Burning
None of the above - Correct Answers -Burning
Of those curves listed, which indicates the flattest base curve?
7.5 mm
37.50 D
8.6 mm
49.00 D - Correct Answers -37.50 D
A contact lens was ordered with a base curve of 7.85 mm but was received back from
the lab with a base curve of 7.80 mm. The base cure of the actual lens is:
0.25 D flatter
0.25 D steeper
0.50 D flatter
0.50 D steeper - Correct Answers -0.25 D steeper
It is noticed that a rigid CL containing a base curve of 7.42mm is fitting quite loose. A
tighter fit may be achieved by changing the B.C. to:
7.46 mm
7.85 mm
8.04 mm
None of the above - Correct Answers -None of the above
A CL has a B.C. of 7.50 mm. Its posterior peripheral curve would most likely be:
7.45 mm
42.50 D
75.35 mm
30.00 D - Correct Answers -42.50 D
The secondary curve of a rigid contact lens generally:
Is steeper than the CPC (Central posterior curve)
1-2 D flatter than CPC
2-4 D flatter than CPC
None of the above - Correct Answers -2-4 D flatter than CPC
The term "hapaptic lens" is used in reference to:
Prism ballast
Truncated
Scleral
Spin cast - Correct Answers -Scleral lens
The CPC of a CL measures 7.5 mm radius of curvature. Its power in diopters is:
41.00 D
42.00 D
45.00 D
,47.00 D` - Correct Answers -45.00 D
The fitting characteristics of a gas permeable rigid CL may be altered by:
Changing the CPC's radius of curvature
Increasing the diameter
Widening the posterior peripheral curve
All of the above - Correct Answers -All of the above
A soft CL demonstrates excessive movement. This may be remedied by:
Larger diameter lens
Smaller diameter lens
Flatter lens
Disinfected lens - Correct Answers -Larger diameter lens
The term "sagittal value" refers to:
Poor fitting lens
Scleral show
Vaulting effect of a CL
None of the above - Correct Answers -Vaulting effect of a CL
When determining the best lens material to use, which of hte following should be
considered:
1. The patient's working conditions
2. Precorneal tear film
3. Full time vs. part time wear
1 only 2 and 3 only
1 and 3 only 1, 2, and 3 - Correct Answers -1, 2, and 3
The gas permeability of a CAB lens is largely dependent upon:
Diameter of the CPC
Width of the CPC
Lens thickness
Lens diameter - Correct Answers -Lens thickness
A rigid gas permeable CL with a B.C. of 7.50 mm is found to be fitting slightly tight. To
improve the fit we might consider changing the B.C. to which of the following:
7.40 mm
7.45 mm
7.55 mm
7.65 mm - Correct Answers -7.55 mm
If the CPC of a rigid CL is held constant while the diameter is increased, it would result
in:
Tighter fit
Looser fit
, Decreased vaulting
Increased gas permeablility - Correct Answers -Tighter fit
When compared with PMMA, CAB lenses:
Have better gas permeability
Fit larger than PMMA
Have lower incidents of corneal edema due to hypoxia
All the above - Correct Answers -All the above
When compared to PMMA which of the following is not ture about CAB lenses?
Have excellent shape retention
Fit tighter
Fit larger
Are better for sports - Correct Answers -Have excellent shape retention
HEMA is an abbreviation commonly used to describe:
Rigid lenses
Gas permeable lenses
Soft lenses
Corneal abrasion - Correct Answers -Soft lenses
Which of the following is not true of PMMA lenses?
Spherical lens corrects to 3 D astigmatism
Easily fabricated
Long history of acceptance
Excellent gas permeability - Correct Answers -Excellent gas permeability
The chief reason to utilize a ballasted CL is:
To correct vertical prism imbalance
Lower the wetting angle
Inhibit lens rotation
Tighten the fit - Correct Answers -Inhibit lens rotation
Which of the following is not true about soft CL?
Specular blur is uncommon
There is less flare and photophobia vs other lenses
Rapid adaption is possible
Spherical can correct medium to high astigmatism - Correct Answers -Spherical can
correct medium to high astigmatism
The central portion of the back surface of the contact lens is called:
The CPC
Primary base curve
Base curve
All of the above - Correct Answers -All of the above
QUESTIONS AND ANSWERS
The first successful contact lens were molded to the shape of the cornea known as:
Corneal
Hapatic
Interpalpebral
Gas Permeable - Correct Answers -Hapatic
Corneal Contact lenses:
Are a typical soft contact lens design
Bridge the limbus and some of the sclera
Are last resort contact lenses
Are common designs for rigid and gas perm contacts - Correct Answers -Are common
designs for rigid and gas perm contacts
The majority of soft lenses fit today are:
Corneal
Hapatic
Semi scleral
Hydrophobic - Correct Answers -Semi scleral
A liquid coming in contact with a hydrophilic lens material with a relatively small wetting
angle would be likely to:
Form beads on the surface
Quickly evaporate
Spread evenly over the surface
None of the above - Correct Answers -Spread evenly over the surface
A contact lens with a diameter larger than that of the cornea is called a ____ lens.
Corneal
Hydrophilic
Hydrophobic
Hapatic - Correct Answers -Hapatic
All of the following are symptoms of a loose fitting lens except:
Constant awareness
,Lid sensation
Burning
None of the above - Correct Answers -Burning
Of those curves listed, which indicates the flattest base curve?
7.5 mm
37.50 D
8.6 mm
49.00 D - Correct Answers -37.50 D
A contact lens was ordered with a base curve of 7.85 mm but was received back from
the lab with a base curve of 7.80 mm. The base cure of the actual lens is:
0.25 D flatter
0.25 D steeper
0.50 D flatter
0.50 D steeper - Correct Answers -0.25 D steeper
It is noticed that a rigid CL containing a base curve of 7.42mm is fitting quite loose. A
tighter fit may be achieved by changing the B.C. to:
7.46 mm
7.85 mm
8.04 mm
None of the above - Correct Answers -None of the above
A CL has a B.C. of 7.50 mm. Its posterior peripheral curve would most likely be:
7.45 mm
42.50 D
75.35 mm
30.00 D - Correct Answers -42.50 D
The secondary curve of a rigid contact lens generally:
Is steeper than the CPC (Central posterior curve)
1-2 D flatter than CPC
2-4 D flatter than CPC
None of the above - Correct Answers -2-4 D flatter than CPC
The term "hapaptic lens" is used in reference to:
Prism ballast
Truncated
Scleral
Spin cast - Correct Answers -Scleral lens
The CPC of a CL measures 7.5 mm radius of curvature. Its power in diopters is:
41.00 D
42.00 D
45.00 D
,47.00 D` - Correct Answers -45.00 D
The fitting characteristics of a gas permeable rigid CL may be altered by:
Changing the CPC's radius of curvature
Increasing the diameter
Widening the posterior peripheral curve
All of the above - Correct Answers -All of the above
A soft CL demonstrates excessive movement. This may be remedied by:
Larger diameter lens
Smaller diameter lens
Flatter lens
Disinfected lens - Correct Answers -Larger diameter lens
The term "sagittal value" refers to:
Poor fitting lens
Scleral show
Vaulting effect of a CL
None of the above - Correct Answers -Vaulting effect of a CL
When determining the best lens material to use, which of hte following should be
considered:
1. The patient's working conditions
2. Precorneal tear film
3. Full time vs. part time wear
1 only 2 and 3 only
1 and 3 only 1, 2, and 3 - Correct Answers -1, 2, and 3
The gas permeability of a CAB lens is largely dependent upon:
Diameter of the CPC
Width of the CPC
Lens thickness
Lens diameter - Correct Answers -Lens thickness
A rigid gas permeable CL with a B.C. of 7.50 mm is found to be fitting slightly tight. To
improve the fit we might consider changing the B.C. to which of the following:
7.40 mm
7.45 mm
7.55 mm
7.65 mm - Correct Answers -7.55 mm
If the CPC of a rigid CL is held constant while the diameter is increased, it would result
in:
Tighter fit
Looser fit
, Decreased vaulting
Increased gas permeablility - Correct Answers -Tighter fit
When compared with PMMA, CAB lenses:
Have better gas permeability
Fit larger than PMMA
Have lower incidents of corneal edema due to hypoxia
All the above - Correct Answers -All the above
When compared to PMMA which of the following is not ture about CAB lenses?
Have excellent shape retention
Fit tighter
Fit larger
Are better for sports - Correct Answers -Have excellent shape retention
HEMA is an abbreviation commonly used to describe:
Rigid lenses
Gas permeable lenses
Soft lenses
Corneal abrasion - Correct Answers -Soft lenses
Which of the following is not true of PMMA lenses?
Spherical lens corrects to 3 D astigmatism
Easily fabricated
Long history of acceptance
Excellent gas permeability - Correct Answers -Excellent gas permeability
The chief reason to utilize a ballasted CL is:
To correct vertical prism imbalance
Lower the wetting angle
Inhibit lens rotation
Tighten the fit - Correct Answers -Inhibit lens rotation
Which of the following is not true about soft CL?
Specular blur is uncommon
There is less flare and photophobia vs other lenses
Rapid adaption is possible
Spherical can correct medium to high astigmatism - Correct Answers -Spherical can
correct medium to high astigmatism
The central portion of the back surface of the contact lens is called:
The CPC
Primary base curve
Base curve
All of the above - Correct Answers -All of the above
