1. When the optical centers of a pair of plus lenses are positioned narrower than the PD, it produces prism base____________.
   
   
2. When the optical centers of a pair of minus lenses are positioned narrower than the PD, it produces prism base_____________.
   
   
3. When a patient looks through a plus lens above the optical center, it produces prism base______________.
   
   
4. When a patient looks through a minus lens below the optical center, it produces prism base________________.
   
   
5. How much prism is induced 5 mm away from the optical center of a +2.00 diopter lens?
   
   
6. How much prism is induced 10 mm away from the optical center of a �0.25 diopter lens?
   
   
7. How much prism is induced 2 mm away from the optical center of a +16.00 diopter lens?
   
   
8. In verifying a pair of spectacles which have recently been returned from the lab, you notice that the optical centers are positioned 61 mm apart. The work order indicates the patient�s PD measures 64
   mm and the prescription calls for -3.00 spheres in each eye. How much total prism is induced and in which direction is the base?
   
   
9. A patient�s prescription calls for OD: +4.75 OS: +2.50. The optical centers of the finished spectacles are found to be positioned 4 mm too wide. How much total prism is induced and in which direction is the base?

(answers on next page)