Term
| What are two testing variations for a presbyopic exam? |
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Definition
- the near cover test should be done through the add if they have one
- the NPC is often reduced
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Term
| What is the appropriate sequence of near point tests for a presbyope? |
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Definition
- distance tests remain the same:
- near tests are different:
- 20, 21, 14b, NS, phoria, vergences
- (PRA, NRA, FCC, NS, phoria, vergences)
- do the phoria and vergences through the lens you are going to prescribe (you want to know what posture you are creating with your rx)
- NOTE: near testing will inevitably start with PRA recovery because you have to add plus to the most minus to yield 20/20; then go directly into NRA to determine the range of accommodation
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Term
| What are four ways to choose the add you will prescribe for a presbyope? |
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Definition
- near subjective
- fused cross cylinder
- PRA/NRA midpoint
- trial frame at working distance (computer glasses?)
NOTE: it has been determined that patient age is the best indicator for what add to prescribe, so be sure to compare age to test results to make sure it makes sense
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Term
| What are four prescribing considerations for presbyopes?? |
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Definition
- write the prescription correctly (SV vs bifocal)
- remember that if you change the distance prescription, youa re changing the total near power (less minus distance rx = more powerful add)
- consider the type of lens the patient will be wearing (PAL, flat top, etc)
- recall: intermediate power on trifocal is half the add power
- adjust for the patient's working distance needs
- take dioptric difference from distance at which test was performed and distance at which the lenses will be made (add plus when closer, subtract plus when farther)
- ex: 40cm = +2.50; 67cm = +1.50; dioptric difference = 1.00D; so decrease the add power by 1.00D if rx for 67cm
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