Fitting of Rigid Daily Wear Flashcards
The contact lens material used widely in the 1950’s and 1960’s was
A. Silicone Acrylate
B. Polymethylmethacrylate
C. Cellulose Acetate Butyrate
D. Hydroxyethylmethacrylate
Polymethylmethacrylate
A contact lens fit with a base curve steeper than the flattest “K” and with a diameter of 8.5 would follow which fitting philosophy?
A. Corneal Alignment
B. 3-Point Touch
C. Apical Clearance
D. 2-Point Touch
Apical Clearance
A typical optical zone diameter of a corneal alignment fit would be
A. 6.5mm
B. 7.0mm
C. 7.5mm
D. 8.0mm
8.0mm
A gas permeable lens which flexes upon the eye would be best corrected by going
A. Steeper
B. Steeper and Thicker
C. Flatter
D. Flatter and Thicker
Flatter and Thicker
A patient with an upper lid that does not cover any portion of the superior portion of the cornea would be best fit
A. Steeper than “K” with a small diameter
B. Flatter than “K” with a large diameter
C. On “K” with an 8.8 diameter
D. Flatter than “K” with a small diameter
Steeper than “K” with a small diameter
A -10.00 Rx for a spectacle correction would most likely need a contact lens with a power of
A. -8.00
B. -9.25
C. -10.50
D. -11.75
-9.25 D
A patient with a base curve of 43.00 D and a power of -3.00 D and then refit with a base curve of 43.50 D would require a new power of
A. -2.50
B. -2.75
C. -3.50
D. -4.00
-3.50 D
A patient with a corneal torocity of 4.50 diopters would be best suited with a base curve that is
A. 1.00 diopter steeper than “K”
B. 1.50 diopter steeper than “K”
C. Toric
D. 1.00 diopter flatter than “K”
Toric
A patient with a base curve of 42.75 D, power of -3.00 D, if refit with a base curve of 43.50 D, would then require a power of
A. 2.50 D
B. 3.50 D
C. 3.75 D
D. 4.50 D
3.75 D
When fitting gas permeable lenses, residual astigmatism is most often caused by
A. High refractive cylinder
B. A toric contact lens
C. Corneal cylinder against-the-rule
D. A difference between refractive and corneal cylinder
A difference between refractive and corneal cylinder
When using original “K” readings to refit a former PMMA wearer with gas permeable lenses, it is best to refit
A. Immediately
B. After seven days of no contact lens wear
C. After one month of no contact lens wear
D. After three months of no contact lens wear
Immediately
A patient fit 0.50 D flatter than “K” with a contact lens power of -1.00 D would most likely have a spherical component of _________ in their spectacle Rx, when in minus cylinder form
A. -0.50 D
B. -1.50 D
C. -2.00 D
D. Plano
-1.50 D
To achieve apical clearance with a gas permeable lens of 8.5mm diameter, fit on a cornea of average size, the base curve should be
A. On “K”
B. Steeper than “K”
C. Flatter than “K”
D. None of the above
Steeper than “K”
A patient with an Rx of +3.00 +0.50 x 090 fit 0.50 diopters flatter than “K” would require a power of
(HINT: SAM/FAP)
A. +3.00
B. +3.50
C. +4.00
D. +4.50
+4.00
Which of the following terms is associated with the corneal alignment fitting philosophy?
A. Central Pooling
B. Intrapalpebral Fit
C. Upper Lid Attachment
D. 3 Point Touch
Upper Lid Attachment
A patient with a +2.00 -1.00 x 090 and “K” readings of 44.00 D @180 / 43.00 D @090 reveals residual astigmatism of plano -2.00 x 180. A possible explanation for this is
A. Normal residual astigmatism
B. A steeply fitted contact lens
C. A warped contact lens
D. A very flat fitted contact lens
A warped contact lens
A patient wearing a 43.00 base curve, 9.0mm diameter, 7.0mm optical zone diameter requires a change to a 9.5mm diameter with a 7.5mm optical zone diameter. To keep the base curve corneal bearing relationship the same, the new base curve would need to be
A. 42.50 D
B. 42.75 D
C. 43.50 D
D. 43.75 D
43.50 D
An Rx of -2.00 -1.50 x 180 and “K” readings of 43.00 @ 180 / 46.00 @090 would have a calculated residual astigmatism of
A. +1.50 @ 180
B. +2.00 @090
C. +1.50 @090
D. +1.00 @180
+1.50 @180
The optical zone of a gas permeable lens is generally designed to be
A. 3.0mm - 4.0mm smaller than the overall diameter
B. 2.5 mm - 3.0mm smaller than the overall diameter
C. 2.0mm - 2.5mm smaller than the overall diameter
D. 1.0mm - 1.5mm smaller than the overall diameter
1.0mm - 1.5mm smaller than the overall diameter
Any ophthalmic lens moved closer to the eye becomes more
A. Flatter
B. Steeper
C. More Plus
D. More Minus
More Minus
The apical clearance fitting philosophy requires a lens that positions
A. Centrally, with upper lid attachment
B. Centrally and intrapalpebrally
C. Superiorly, with upper lid attachment
D. Superiorly and intrapalpebrally
Centrally and intrapalpebrally
A diagnostic lens with a base curve of 7.67mm and an optical zone diameter of 7.6mm fits too tight. Which of the following changes will loosen the fit the most?
A. 7.76mm, 8.0mm
B. 7.69mm, 7.8mm
C. 7.63mm, 7.6mm
D. 7.71mm, 7.3mm
7.71mm, 7.3mm
Gas Permeable lens edge thickness should be between _________mm and ________mm
A. 0.02 - 0.05
B. 0.05 - 0.10
C. 0.08 - 0.12
D. 0.10 - 0.30
0.08 - 0.12
Which of the following is NOT an advantage of gas permeable lenses over soft lenses?
A. Longer lens life
B. Better initial comfort
C. Better optical quality
D. Fewer adverse effects
Better comfort
