Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
Prentice's Rule |
Determines the prism induced by viewing through a lens at a location other than the optical center Induced Prism = d|F| |
|
|
BI Prism |
- Causes the image to appear further away - Causes pt to diverge - Pt requires larger NFV to maintain single, comfortable vision |
|
|
Testing PFV |
BO prism or plus lenses |
|
|
Testing NFV |
BI prism or minus lenses |
|
|
Range Important for Exophoria |
PFV |
|
|
Range Important for Esophoria |
NFV |
|
|
Plus Lenses |
- Induce accommodative divergence - To maintain fusion, PFV must increase |
|
|
Minus Lenses |
- Induce accommodative convergence - To maintain fusion, NFV must increase |
|
|
Needed to Calculate Image Jump |
- Add power - Bifocal style |
|
|
Prism Direction Induced by Add |
BD Image jump occurs from looking above the OC of a plus lens, so base direction is BD |
|
|
Determine Total Binocular Prism |
Horizontal: If both BO or BI, add! If opposite, subtract. Vertical: If both BO or BI, subtract! If opposite, add. |
|
|
Uncrossed Deviation |
Caused by an eso deviation |
|
|
Crossed Deviation |
Caused by a exo deviation |
|
|
Meridian of Rotation for Pantoscopic Tilt |
180 |
|
|
Meridian of Rotation for Faceform Tilt |
90 |
|
|
Pantoscopic Tilt in Minus Cyl |
Minus lens: Induces an axis at 180 Plus lens: Induces an axis at 90 |
|
|
Pantoscopic Tilt and PALs |
Good because it moves the reading portion of the lens closer to the eye |
|
|
More on Pantoscopic Tilt |
- Increases lens distortions - Alters cyl effect - Induced by adjusting temple angle - Lowers the lens so it is helpful if the OC is too high |
|
|
Retroscopic Tilt |
Top of the lens is closer to the face than the bottom of the lens Opposite of Pantoscopic Tilt |
|
|
Solution: Glasses Fall Down Nose |
Pull in the temples Bend down temple tips Pull in nose pads to tighten fit |
|
|
Solution: One Lens Feels Closer to Face than the Other Lens |
Straighten the temples |
|
|
Solution: Glasses Touch Cheek |
Reduce Pantoscopic Tilt Narrow bridge or pads to raise frame Narrow bridge or pads to increase vertex distance |
|
|
Solution: Glasses Too Close to Face |
Narrow the pads Shrink the bridge Decrease face form to move lenses away from the face |
|
|
Solution: Frames Sit Too Low on Face |
Narrow the bridge Add pads Lower vertical position of pads to move frames up on face |
|
|
If Seg Appears too High |
- Increase Pantoscopic tilt - Decrease vertex distance - Spread the pads - Move pads up by adjusting pad arms - Stretch the bridge |
|
|
If Seg Appears Too Low |
- Narrow the pads - Move pads down by adjusting pad arms - Increase vertex distance - Reduce Pantoscopic Tilt - Shrink the bridge |
|
|
To Lower the Segment |
- Increase distance between nose pads - Raise the vertical portion of the nose pads - Widen the bridge Need to lower the frame on the face |
