Week 4 - Adapting to Rigid Lenses Flashcards
Major Reasons for Discomfort with RGP’s
Why do the edge of an RGP cause discomfort? 4 (prescription2/design/general)
- Poorly contoured edges or poorly blended peripherial
curves. - Thick edges
- High Minus needs a lenticular cut to center lower
- high plus, aphakic lens to help keep lens high (thicker lens will make it drop down)
Major Reasons for Discomfort with RGP’s
A lens that is stored dry causes discomfort. T/F
TRUE
Major Reasons for Discomfort with RGP’s
The smaller the lens means their is less lid attachment so the px notices the lens more.
What happens everytime the px blinks?
the eyelid has to glide over the lens edge which is uncomfortable
Major Reasons for Discomfort with RGP’s
What 2 situations with an RGP lens cause mechanical abrasions? 2
-BC too flat
-deposits on lens surface
Major Reasons for Discomfort with RGP’s
If the edge is too steep in relation to the eyelid how will the lens be decentered?
Lens is decentered inferiorly (down)
Major Reasons for Discomfort with RGP’s
If the edge is too flat in relation to the eyelid how will the lens be decentred?
Lens is decentered superiorly (up)
Major Reasons for Discomfort with RGP’s
The patient will notice the lens in. Is there something wrong with the lens?
No there is not a fitting issue, the feeling of excessive lens movement will go away with adaption
Major Reasons for Discomfort with RGP’s
If the optic zone size is too small, what can it cause and what do we do to fix it?
-Can cause flare
-we need to make the optic zone larger
Major Reasons for Discomfort with RGP’s
If the lens is decentered, what can it cause and what do we do to fix it?
-Can cause flare
-fix issue as to why it is decentered
Major Reasons for Discomfort with RGP’s
Mild Photophobia is normal.
What is normally wrong with the lens for it to cause photophobia?
usually due to a flat fitting lens
Major Reasons for Discomfort with RGP’s
The patient will tear when getting use to RGP lenses. This should go away as the patient adapts.
What can the px experience when they are tearing up? 2
- the lens can become dislodged
- variable vision
Major Reasons for Discomfort with RGP’s
If the patient is tearing up excessively what should we check for?3
What can we change to help? 2
- The edges (thick edges can cause tearing)
- Check the lid impact (Can cause frothing/ greasy film over lens)
- Inspect periphery of lens
- Change to higher Dk material
- Change fit
What kind of lens design has 1 curve (BC) on the Radiuscope and 1 power on the lensmeter?
Example: 7.03(48.00) -4.00
Spherical lens
What kind of lens design has 1 curve (BC) on the radiuscope and 2 powers on the lensmeter?
Example: 7.67(44.00) -2.00/-4.00
Front Toric
What kind of lens design has 2 curves (BC) on the radiuscope and 2 powers on the lensmeter?
Use Example
7.85/7.50 (43.00/45.00)
-2.00/-3.00
Bi -Toric as the residual astigmatism is MORE THAN 0.75D
43.00-45.00=2.00
(-2.00)(-3.00) difference = -1.00
2.00-1.00=1.00
Residual astigmatism = -1.00