Hi guys,
I'm going through a few questions in my book. For the following, I don't understand differential prisms or really anything in these questions. It doesn't seem to be anywhere in my books! Can anyone do them, so I can see the working, or can someone point me in the direction of formulas etc pleeease?
There are as follows:
5) A prescription reads:
RE 3.5 base up, 1.5 base out
LE 6.5 base down, 7.5 base out
I need to equally divide the prism between the 2 eyes.
6) Another prescription reads:
RE 5 base up
LE 9 base out
I need to equally divide the prism between the 2 eyes.
7) Calculate the total prism in each eye, and the differential prism, when the wearer of the following prescription looks at an object through points 12mm to the left (from the wearer's perspective) and 8mm up from the distance optical centres.
RE +6.75D
LE +1.50D
8) Calculate the total prism in each eye, and the differential prism, when the wearer of the following prescription looks at an object through points 10mm to the right (from the wearer's perspective) and 8mm up from the distance optical centres.
RE -2.25D
LE -5.50D
9) Calculate the total prism in each eye, and the differential prism, when the wearer of the following prescription looks at an object through points 6mm to the right (from the wearer's perspective) and 10mm up from the distance optical centres.
RE -3.50D
LE +2.50D
10) A prescription reads RE +5.00D, LE+5.00D. If the wearer os this prescription looks through a point 8mm above the optical centres, will she or he experience any differential prism? If so, how much? If not, why not?
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