Quiz 12 Flashcards
A tricurve GP lens with BCR 7.75mm/OAD 8.80mm shows an alignment fit on a normal cornea with 0.00D corneal astigmatism. Which of the following would you expect to find, after changing the lens parameters to BCR 7.70mm/OAD 9.20mm?
a. A perfect alignment pattern
b. A symmertical central pooling pattern
c. A symmertical aprical touch pattern
d. A dumbbell shape pattern oriented horizontally
e. A dumbbell shape pattern oriented vertically
A symmetrical central pooling pattern
A tricurve GP lens with OAD 9.20mm is fit on a normal cornea with -2.00x180 corneal astigmatism. The BCR of the lens was chosen according to a common fitting guide. Which of the following would you expect to find, after instilling fluorescein?
a. A perfect alignment pattern
b. A symmertical central pooling pattern
c. A symmertical aprical touch pattern
d. A dumbbell shape pattern oriented horizontally
e. A dumbbell shape pattern oriented vertically
d. A dumbbell shape pattern oriented horizontally
A tetra-curve GP lens with BCR 7.80mm/OAD 9.80mm is fit on a normal cornea with -2.00x180 corneal astigmatism. The fluorescein pattern shows a dumbbell shape pattern with heavy bearings along the 3 and 9 o’clock positions. Which of the following is the best strategy to improve this fit?
a. Increase OAD by 0.10mm
b. Decrease OAD by 0.10mm
c. Increase BCR by 0.10mm
d. Decrease BCR by 0.10mm
c. Increase BCR by 0.10mm
A tetra-curve GP lens with BCR 7.80mm/OAD 8.80mm is fit on a normal spherical cornea. In static evaluation, the fluorescein pattern shows alignment. In dynamic fit the lens decenters so far inferiorly, that the optic zone doesn’t cover the entire pupil. Which of the following the best strategy to improve this fit?
a. Increase OAD by 0.80mm and increase increase BCR by 0.10mm
b. Increase OAD by 0.80mm and decrease BCR by 0.10mm
c. Increase OAD by 0.40mm and increase BCR by 0.10mm
d. Increase OAD by 0.40mm and decrease BCR by 0.10mm
a. Increase OAD by 0.80mm and increase BCR by 0.10mm
