Originally Posted by
Agnieszka
Hi, My name is Agnieszka.I am doing the optical technician course and I have problems with my course question.Could anybody help me?Thank You very much.
1. A patient wears a spectacle frame whose BCD is 68. The Rx is +3.00 each eye and his Pd is 64. If the largest available blank was not large enough to optain the required decentration, what prism must be worked and in what direction, to obtain the centres in the correct position from a standard blank size?
Base in prism, and if it's just to obtain the decentration then 1.25PD
2. A prismatic Rx has been ordered of 2.5 prism dioptres Base IN each eye on an Rx, BE -5.00D.
What would be the minimum blank size possible to produce this prism for an eyesize of 45mm by decentration?
55mm
3. A patient looks through a point 5mm above the lens optical centres of Rx BE +4.00D. How much prism (including the base direction) does the patient encounter?
2 BD
4. If the Rx in question 3 was: R +4.00D and L -4.00D, how much total prismatic imbalance would there be between the two eyes?
4 PD
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